MARINE CONTAMINANTS (beyond plastics)

Ocean pollution is widespread, crosses national borders, and over 80 % originates from land-based sources and human activities. This complex mixture, including chemical, biological, and physical agents that can interact and amplify their effects, poses a threat to marine ecosystems and human health.  103 ANR projects have studied various contaminants such as metals, persistent organic pollutants (POPs), and nanomaterials. They have led to significant advances in the detection and fate of pollutants, the restoration of contaminated ecosystems, and the use of sentinel species for biosurveillance. Among the challenges for research: studying the impacts of low doses of pollutants on ecosystems and human health; using omics tools to understand biological responses; and improving risk management scenarios to anticipate environmental crises.

Catherine Mouneyrac: University of Angers UCO 

Scientific background

Ocean pollution is widespread, crosses national boundaries and arises for more than 80% from land-based sources and anthropogenic activities. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is a complex mixture including chemical (organic and inorganic), biological (pathogens, viruses) and physical (nanomaterials, plastics, light, noise) agents which can interact amplifying their effects. Pollution is most highly concentrated along the coasts. Coastal eutrophication and acidification are one of the threats to the health of coastal social-ecological systems worldwide.

Ocean pollution has negative impacts on marine ecosystems and its threats to human health are great, but still incompletely understood. Over the past two decades, significant progress has been made in monitoring and detection (development of sensors, analytical techniques) of pollutants. Ecotoxicological studies has allowed advances in understanding sublethal effects, modes of action of pollutants at different levels of biological organization (molecular, organism, ecosystem) and growing knowledge of the "mixture effect" of multiple pollutants.  The interaction between climate change and marine pollution has been assessed on diverse species since increase of temperature is one of the major global issues, threatening the planet. 

Ocean pollution can be prevented. Like all forms of pollution, marine pollution can be controlled by deploying data-driven strategies based on law, policy, technology, and enforcement that target priority pollution sources. Restrictive regulations have been implemented such as the Grenelle de la mer (France), international conventions, such as the MARPOL, Stockholm Convention (Persitent Organic Pollutants  POPs) or the European Marine Strategy Directive. Successes achieved to date demonstrate that broader control is feasible. Heavily polluted harbors have been cleaned, costal and estuarine ecosystems restored. While significant progress is being made in understanding and mitigating ocean pollution, the scale of the issue requires a unified global effort combining science, technology, policy, and public engagement. 

Main Contributions of the French Communities through ANR (co)funding (Action plan and France 2030)

Over the last two decades, ANR has funded sixty-six projects on ocean pollution. The presence, fate and behaviour of contaminants in marine compartments as well as their impact on biota have been studied. A large variety of conventional and emerging contaminants (metals, POPs, nanomaterials, cyanobacteria, viruses), which pose significant risks to human health have been investigated. For example, the destruction of coral reefs in Pacific can be the cause of cyanobacterial blooms that produce toxins (anatoxin-a, ciguatoxin-like, palytoxin…) leading to human poisoning by seafood (ARISTOCYA). Eutrophication due to phosphorus inputs induced either by uncontrolled urban and industrial discharges or soil erosion led to the degradation of fishing and water supply areas (Vietnam) and is accompanied by toxic cyanobacterial blooms (DAY RIVER).

A huge effort in the development of devices has been performed to detect pollutants in the marine environment, such as metals (Lab-on-Ship), organic compounds (REMANATHAS), underwater sound waves (HYDRE) or cutting-edge technologies to deal with the consequences of pollution accidents, for example at a French nuclear reactor (PIA DECLIQ). Because adverse effects of chemical contaminants to the environment and humans have been widely described, the restoration of contaminated areas is a priority. Restoration with leguminous species had a positive effect on soil chemical quality highlighted by a positive effect on mercury speciation by reducing its mobility. (RIMNES). Concerning pollution by petroleum compounds, a transportable device for cleanup ships capable of detecting drifting oil slicks at sea has been proposed (DETHERPOLMAR) as well as detect oil spills with airborne surveillance radar (POLSHAR) The use of dispersant accelerate the attenuation of hydrocarbon contaminated mudflat sediments andd dispersed oil had no effect on the diversity of bacterial and macrofaunal organisms., Microbial communities of coastal sediments were involved in hydrocarbon degradation under real environmental conditions (DECAPAGE). The Gironde estuary, has been subjected for long time to industrial metal pollution from the Lot river (highlighted early in the 1970s). A remediation process was initiated on Riou-Mort watershed, a mining site contaminated by metals. The first impacts of remediation on periphytic biofilms, did not reveal a decrease of metal accumulation in biofilms revealing that recovery of aquatic communities after remediation can only be expected in the long term (RE-SYST). Remediation techniques of ecosystems contaminated by pesticides such as chlordecone in west-indies is a real challenge as well as for ecosytems than Humans.

Sentinel species of the water column (bivalve molluscs), widely used for the assessment of levels of contaminants (Mussel Watch programmes, Réseau National d’Observation de la qualité du milieu marin, Ifremer) as well as for examining their biological effects (International Council for the Exploration of the Sea) have been employed. Sediments are the final sink for most contaminants issued from human activities (metals, pesticides, hydrocarbons…). Following the earthquake and resulting tsunami in Japan in 2011, an unprecedented release of artificial radionuclides to the ocean from the Fukushima Daiichi nuclear power plants appeared. The nearshore sediments off Japan will remain a significant long-term source of radiocesium for years to decades (PIA AMORAD).

A guide of ecological risk assessment for the management of dredged sediments of ports has been proposed (SEDIGEST). Long-range atmospheric deposition also accounts for some of the variations in isotopic composition measured in the sediments. The coupling of Pb isotopes with Zn or Fe isotopes allows to identify and constrain the metal sources that contributed to sediment contamination (Artic metals). Endobenthic species (cockle, flounder, sole) exposed to sediment-bound contaminant, are also recognized as good models for biomonitoring purposes. Sediments also provide habitat, feeding and breeding areas for a number of benthic organisms. For example, a chronic pollution has been shown of the spawning grounds of the European sturgeon in the Garonne and more in the Dordogne and a contrasting toxicity of the sediments with respect to the sturgeon embryos and larvae (STURTOP). However, pollutant storage is not definitive and the contaminants can be remobilized and contaminate the water column for example of storms or dredging. The combined effects of contaminants and nutrients released from sediment into the water column during resuspension-mixing events were assessed on the phytoplankton composition and productivity in the anthropized lagoon of Bizerte (Tunisia). Results showed that sediment resuspensions are likely to have significant effects on the structure and productivity of pelagic primary producers. Lagoon site communities appeared to be more resilient (mechanisms of resistance) compared with those from a reference site (RISCO). Another study conducted at the Calanque National Park which constitutes one of the ten biodiversity hot spots identified in the Mediterranean basin and receives industrial and urban wastewaters discharged from Marseille and its suburbs. Results confirmed that PCBs and organochlorine pesticides in sediments induced toxic effect towards marine biota and more particularly for benthic communities (MARSECO). A special attention has been paid to endangered species such as eel or sturgeon to elucidate their toxicological status linked to populations decrease (ELL—SCOPE, IMMORTEEL, STURTOP). POPs are one of the suspected causes of this decline. Eels from the Gironde estuary confirmed the high level of PCBs in yellow eels’ muscle, and PBDEs contamination (ELL-SCOPE).  The use of species with a short life cycle, such as the zebrafish, a model widely used in ecotoxicology, allowed exposures starting with larva up to sexually mature adults. Detrimental consequences of exposure to PAHs were shown on fish performances and contribution to recruitment (CONPHYPOP).

In the environment are present a mixture of contaminants and their metabolites. Analyzing several classes of compounds present at trace or ultra-trace concentrations (ppb or ppt) requires the use of sophisticated apparatus and protocols. These requirements are very time-consuming, costly and some chemicals are not yet accessible for quantification. Therefore methodologies have been developed to estimate the average concentrations of pollutants in the environment taking into account the temporal variability of the contamination. Passive samplers (Semi Permeable Membrane Devices : SPMD, Diffusion Gradients in Thin film : DGT, Polar Organic Chemical Integrative Sampler : POCIS) are useful tools (ESMETOX). Assessing the impact of chemical pollution cannot be met on the basis of pollutant analysis alone since only a fraction of bioaccumulated chemicals can exert noxious effects on biota because of detoxification mechanisms in the organisms. Combining both biological responses and chemical analyses allows to identify toxic hot-spots, to characterize chemicals likely to cause adverse biological effects. The multi-biomarker approach based on sensitive and early warning signals providing information on the toxicity of mixture of pollutants on organisms has been extensively used over the last 30 years.  For example, atlantic cod were exposed to the water-accommodated fraction of different oils. PAH metabolites in bile confirmed exposure to and uptake of PAHs. Biomarker responses (CYP1A system and oxidative stress) in fish were able to discriminate among oil types and to monitor the environmental consequences of spills (AMPERA). Ecotox tests (applicable to high-throughput analysis), using marine embryos, have been proposed as useful tools for monitoring pollution (endocrine disruption, teratogenicity, genotoxicity) (MarineEmbryoTox). Combined biological and chemical-analytical approaches provide an important progress towards an estimation of the portion of an effect that can be explained by the analyzed chemicals. In this context, integrated strategies such as effect-directed analysis (EDA) are powerful tool to elucidate unknown causative toxicants in complex environmental samples and their combined effects, thus improving environmental risk assessment (ESMETOX). EDA showed that petrogenic components were responsible for the estrogen receptor and the androgen receptor mediated activity in north sea offshore produced water discharges. A guide to assess the impact of marine oil spills combining biological-effects techniques has been proposed. (AMPERA).

Studying low dose effects particularly in the case of exposure to mixtures constitutes a real challenge. Approaches helping to characterize the response of marine organisms to multi-contamination without preconception are key for understanding the impact of contaminants. Omics tools now make it possible to obtain considerably more complete and specific information on the biochemical response of organisms to biotic and/or abiotic stress. Environmental metabolomics, based on the identification of low molecular weight metabolites (50–1500 Da) whose production and levels vary with the physiological, developmental, or pathological state of cells, tissues, organs, or whole organisms has been applied to investigate deeply mechanisms and modes of action of contaminants. The response of mussels to waste water treatment plants effluents (pharmaceutical products) was characterized by the presence of a high quantity of modulated metabolites (e.g. amino acid, neurohormones, purine and pyrimidine metabolism, citric acid cycle intermediates (IMAP). Nowadays, there is still a controversy in whether environmental-induced changes in epigenetic marks (DNA methylation) can be inherited from one generation to the next. Cd exposure led to a progressive feminization of the population of fish (Danio rerio) across generations. A significant relationship has been shown between the methylation level of the foxl2a gene in mother gonads and the sex ratio of their offspring (TRACE). 

Metal pollution in the marine environment and their impacts have been regularly investigated on diverse species. Innovative tools (speciation, isotopes) were developed to discriminate metals sources (anthropogenic vs natural), mobility and reactivity and assessed their bioavailability for biota. The mechanisms involved in the production of the isotopically heavy Fe may lead this tracer to become a new indicator of environmental changes occurring in the boreal zone (Artic metals). Mercury, present under different chemical forms, along its biogeochemical cycle, can be accumulated and bioamplificated in aquatic food chains. Mercury speciation and stable isotopes fractionation in French Guiana highlighted the real impact of gold mining on native population (RIMNES). The consumption of seafood (Tuna), represents the main source of human exposure to methylmercury (main toxic form).  The first global maps of MeHg concentrations realized in different species of tuna for the global ocean, illustrates the geographical influence of anthropogenic mercury sources and the role of natural ocean processes (Mertox).

Among the POPs, emerging contaminants such as Pharmaceutical and Personal Care Products (PPCAs), Polybrominated Diphenyl Ethers (PBDEs) are ubiquist in the environment in the form of mixtures of different congeners (PEPSA). Antibiotics, antidepressants, and antifungals would deserve attention because of their ecological risk on marine ecosystems (Pharm@cotox). The long‐term effects of a diet exposure to mixtures of PBDEs and/or PCBs at environmentally relevant levels in zebrafish showed endocrine disruptions and an altered reproduction physiology. In the offspring, significant physiological, behavioural alterations and demographic effects (energy was reallocated from reproduction towards growth) were observed which added onto the altered offspring performances (Fish'N'POPs). 

The widespread use and release of nanomaterials in marine ecosystems is a concerning issue which has been also investigated. For example, the use of sunscreens leads to the release of nanoparticles in water. The quantification and characterisation of the released forms of by-products showed that nano-TiO2 UV filters rapidly loose their hydrophobic properties in contact with water and under light. Daphnia and Danio rerio were contaminated by sunscreen residues, but the stability of the external inorganic layer (AlOOH) of the nano-TiO2 UV filter lead to a strong decrease of the toxicity compare to bare Nano-TiO2 particles (AgingNano&Troph). There is today a strong demand (from both industry and consumers) for new innovations enabling the production of alternatives to current UV filters that are both renewable and safer.

The interaction between climate change and marine pollution has been assessed. Surface water temperatures at the spawning grounds of sturgeon have been shown that embryo-larval stages were very sensitive to temperature, and to a lesser degree hypoxia and chemical pollution (SturTOP). The influence of life history of species in the response to heat stress confirmed the vulnerability of populations to the increase in temperatures (IPOC). Highly contaminated flounders from the multi-contaminated Seine displayed a lower tolerance to thermal stress, compared to moderately contaminated fish from Vilaine (EVOLFISH). In the marine environment, bivalve mollusks constitute habitats for bacteria of the Vibrionaceae family. Differences in immune effectors could contribute to the higher resistance of mussels to infections (vibrios). Global warming and antimicrobial resistance (AMR) impact aquaculture as shown by infected aquatic animals presented higher mortalities at warmer temperatures (Labex Cemeb). Countries most vulnerable to climate change will probably face the highest AMR risks, impacting human health beyond the aquaculture sector.

In conclusion, ANR funded projects contributed to the structuring of the French (e.g. GDR Ifremer-INRA IMOPHYS : Integration of Molecular and Physiological responses to contaminants in coastal areas, Labex Cemeb) and international communities (e.g. France-Canada ECOBIM network, international joint laboratory : LMI COSYS-Med, IRD and the Tunisian Ministry of Research and Higher Education)  pooling of expertise teams (universities, organismes nationaux de recherche : CNRS, RD, INRAE, BRGM)  operating in the environment field (ecology, ecotoxicology, human health, biology, physiology, soil science, environmental chemistry, modelling). 

Research perspectives coming out of the ANR (co)funded projects 

Currently, 37 projects are in progress. The upgraded technology readiness levels and featuring enhanced metrological performance with the aid of AI and innovative accelerated numerical methods. This allows significant advances in pollution detection and monitoring in seas and high-risk zones such as coasts and ports. Currently, 10 projects aim developing new sensor technologies (e.g. radar, sensor equipped with a sampling drone to detect and monitor marine pollution (metals, phycotoxines, virus, pesticides, petroleum hydrocarbons, methane, nitrate, phosphate…). 

Better understanding marine ecosystem vulnerability (estuaries, coasts, coral reefs) to stress such as contaminants, acidification, eutrophication climate‐related environmental stress ; from individual responses to ecosystem health status assessment is always a real challenge. Despite long-term efforts, estuarine and costal ecosystems are impacted by several global change but only few are now in recovery. Coral reefs (4 projects) are well explored since critically endangered by anthropogenic stressors (chemicals, UV-filters, temperature, acidification), and the decline in many fish species needs understanding fish larval recruitment, a key step to preserve coral reef fish populations, improve their nutritional and safety quality because consumed by local populations. Generally, it is essential to better understand and predict the propagation of effects between trophic levels of marine systems.
One of the main issues in ecotoxicology nowadays is understanding the effects of exposure to pollutant low concentrations on organisms' vulnerable life stages, life history, as well as their multi- and transgenerational effects. Recent works highlight the role of epigenetic alterations in mediating the response to environmental toxicant exposure. Massive gaps of knowledge is in understanding of toxicity (modes of action) of endocrine disruptive compounds. The potential of metabolomics  is powerful to highlight key metabolites disrupted by pollutants and then elucidate the biological effects of such exposure but there is  currently a lack of knowledge on metabolism of marine species. Addressing the combined effects of mixture of pollutants remains a significant challenge due to the complexity of interactions. There is a lack of knowledge of the occurrence, fate and toxicity of rare earth elements (e.g. lanthanides, indium, germanium), PPCPs, PFAs, pesticides (chlordecone) and their metabolites. Little research is conducted on the impact of noise and light on marine species, particularly in harbors. It is crucial to investigate putative disruption of the biological timing of marine organisms living in coastal environments and evaluate their consequences. It is also necessary to improve the ability of states to anticipate the future by producing reliable and robust 'worst-case scenarios' to overcome both technical and natural hazards such as industrial release, earthquake, a tsunami or a major nuclear accident.  

In conclusion, ocean pollution remains a critical global challenge requiring intersectorial (natural sciences and engineering, human and social sciences), interdisciplinary (ecology, ecotoxicology, analytical chemistry, sociology, law) and stakeholder expertise approaches. Prevention and remediation of ocean pollution creates many benefits. It boosts economies, increases tourism, helps restore fisheries, protect marine ecosystems (pollution-free marine protected areas) for future generations and improves human health and well-being.

PLASTIC POLLUTION

4.8 to 12.7 estimated million tons of plastic waste enter the ocean each year. Invisible but massive pollution, microplastic particles (<5mm) and nanoplastics (<1µm) are now ubiquitous in all environmental compartments (oceans, soils, air, polar ice); they are detected in drinking water, food, air, and even human tissues. 25 projects supported by the ANR have led to significant advances in understanding the nature, fragmentation, and biological impacts of micro and nanoplastics; the role of estuaries as critical zones for their accumulation and redistribution; and the evaluation of the interaction between plastics and biota. Among the emerging topics: the role of plastics as vectors of pathogens and invasive microorganisms; and understanding the complexity of pollution by these particles across ecosystems, food webs, and human health, particularly for nanoplastics.

Richard Sempere: CNRS, Aix- Marseille Université

1) Scientific background:

Over the past two decades, the global understanding of plastic pollution has undergone a major transformation. Initially perceived primarily as a problem of visible litter, research has since revealed the complex and pervasive nature of plastic pollution, particularly in the form of microplastics. Scientific progress has expanded knowledge on the sources, environmental pathways, impacts on ecosystems and human health, and the societal responses required to address this challenge. Estimates of total plastic entering the ocean vary significantly depending on data sources and modeling approaches. Early studies, such as those by Jambeck et al. (2015), estimated that between 4.8 and 12.7 million tons of plastic waste enter the ocean annually from mismanaged coastal waste. More recent research, including the work of Weiss et al. (2021), has refined these estimates by incorporating a wider range of sources, such as terrestrial runoff, riverine inputs, and atmospheric deposition. These refined models highlight both the magnitude of plastic pollution and the considerable uncertainty that still exists. Within this broader context, microplastics—defined as plastic particles less than or equal to 5 millimeters in size—constitute a specific and particularly challenging subset of plastic pollution. According to recent assessments, notably Thompson et al. (2024), annual emissions of microplastics into the environment are estimated between 10 and 40 million tons. These microplastics originate from both primary sources (such as microbeads, industrial pellets, and synthetic powders) and secondary sources, resulting from the fragmentation of larger plastic debris during use, waste processing, or environmental degradation.
Microplastics are now widely distributed in all environmental compartments, including the deep sea, coastal sediments, rivers, soils, air, and even polar ice. They are transported over long distances and persist in the environment. Microplastics have been detected in more than 1300 species, including zooplankton, invertebrates, fish, birds, and marine mammals. Evidence from laboratory and field studies demonstrates effects at all levels of biological organization, from cellular stress and tissue inflammation to reduced growth, reproduction, and changes in species behavior. The smallest plastic particles, known as nanoplastics (typically <1 micrometre), are particularly concerning due to their potential to cross biological membranes, interact with cells and tissues, and trigger toxic effects. However, current detection technologies for nanoplastics remain limited, which constrains risk assessment. Biodegradation, when it occurs, depends on polymer type and environmental factors such as temperature, light, oxygen availability, and microbial activity. In many cases, full mineralization is extremely slow or incomplete.

Microplastics/nanoplastics have been found in drinking water, food products (including seafood, salt, fruits, and beverages), and indoor and outdoor air. Recent studies have also detected microplastic particles in human tissues, including lungs, blood, placenta, and digestive systems. While evidence of direct health effects in humans remains limited, laboratory studies suggest potential links to inflammatory responses, oxidative stress, and endocrine disruption. The recent findings have significantly expanded the knowledge base on the sources, fate, and risks associated with micro- and nanoplastics. Additionally, leachates of plastic additives from all manufactured including usual equipment, textiles, tire wear and antifouling paints, are now recognized as major vectors of toxicity. However, challenges remain in establishing dose-response relationships and exposure thresholds due to methodological variability and insufficient long-term data. A precautionary approach is increasingly seen as justified in public health policy.

In response to growing scientific evidence and public concern, a range of policy measures have emerged at national and international levels. These include bans on microbeads in personal care products, regulations on industrial pellet handling, requirements for washing machine filters, and integration of microplastics into regulatory frameworks such as the EU Marine Strategy Framework Directive and REACH regulation. At the global level, microplastics are now part of the negotiations under the draft United Nations Global Plastics Treaty. While many current policies focus on downstream mitigation, scientific consensus increasingly supports upstream measures, including redesign of products, reduction in plastic production, improved waste management, and development of sustainable alternatives. Research into bioplastics and so-called biodegradable materials shows that under real-world conditions, they often fragment similarly to conventional plastics and may retain ecotoxicological risks. Degradation rates depend heavily on polymer type and environmental context. Current evidence suggests that these materials must be critically assessed before being promoted as sustainable alternatives. Addressing plastic pollution calls for interdisciplinary collaboration among chemistry (for polymer characterization and green material design), oceanography and biogeochemistry (for transport and degradation processes), ecotoxicology, engineering, economics, and international legal frameworks. Plastic pollution is not only an environmental issue—it is a systemic problem tied to production and consumption models, requiring innovation, regulation, and global coordination.

2) Main Contributions of the French Communities through ANR (co)funding (Action plan and France 2030)

A range of recent French-led research initiatives on plastic pollution have contributed major new insights into the nature, transformation, and impacts of micro- and nanoplastics in the environment like in NANOPLASTICS and PEPSEA projects among others. These projects (Table 1), although diverse in their disciplinary approaches, converge on several key scientific priorities. Firstly, advances were made in understanding the environmental fate and transformation of plastics. Fragmentation into micro and nanoplastics, as well as their biofouling, were found to significantly alter transport dynamics in both freshwater and marine environments. Estuaries emerged as critical zones of accumulation and redistribution, where the behavior of particles depends on biofilm development, density shifts, and tidal cycles. The atmosphere has also been identified as a significant, though understudied, compartment in the global plastic cycle. Air-sea exchanges driven by bubble bursting are believed to play a role in the long-range transport of micro- and nanoplastics. Secondly, several projects such as Sedi-PLAST highlighted the importance of sediment archives in reconstructing historical contamination patterns, especially across major rivers like the Seine, Loire and Rhône. These studies produced the first temporal records of microplastic accumulation over decades, offering baseline data for assessing mitigation policies.

At the biological level, significant progress was made in evaluating the interaction between plastics and biota (MicroplastiX, OXOMAR). Some projects such as MycoPLAST focused on fungal communities capable of degrading plastic polymers, while others explored the role of microplastics as vectors for toxic substances and human pathogens. Chronic exposure of fish to biodegradable plastics has also been shown to affect their microbiota, metabolism, and energy balance (EPHEMARE, PLASTOX). The complexity of these interactions underscores the need for long-term studies integrating molecular, ecological, and toxicological perspectives. On the methodological front, substantial innovation occurred. New reference particles mimicking real environmental polyethylene debris were developed for toxicity assays. Protocols to produce micro- and nanoplastics with specific additives and surface modifications were optimized, for instance in ANDROMEDA, improving relevance for risk assessment.

Spectroscopic and chromatographic techniques were refined for smaller particle size detection, down to the sub-micron scale. Modeling tools were enhanced to simulate vertical and horizontal dispersion in coastal systems and to couple oceanic and atmospheric pathways. The biodegradation of conventional and biodegradable plastics under realistic marine conditions remains a key research challenge (SeaBioP). Projects explored how polymer chemistry, particle size, and biofilm formation affect degradation rates and mechanisms. It is now evident that so-called biodegradable plastics may persist longer than expected and may produce secondary pollution if not properly managed.

Several research efforts explicitly engaged with social and economic actors. Citizen science initiatives advanced protocols for participatory monitoring of microplastics in the Mediterranean. Public health risk assessment was also incorporated, especially in the context of artisanal fisheries and pathogen transfer. The development of stable marine foams as filtration systems and advanced oxidation processes for nanoplastic removal represent promising innovations with potential for industrial application (BASEMAN, ANDROMEDA among others). Altogether, these results reinforce the urgency of adopting systemic, interdisciplinary approaches to address plastic pollution. Chemistry, oceanography, microbiology, toxicology, modelling, social sciences, and law must work together to characterize, monitor, and ultimately reduce plastic contamination across the full aquatic continuum. Several projects strengthened the interface between science and society through participatory approaches and awareness tools. Protocols were developed to involve citizens in microplastic monitoring, particularly in the Mediterranean, promoting open and inclusive science. Human health risk assessments were integrated into studies of plastics as vectors of pathogens, especially in artisanal fishing zones. Some projects contributed to the standardization of measurement methods, paving the way for indicators usable in European regulatory frameworks. Innovative low-impact materials (e.g. marine foams, advanced oxidation processes) were tested for real-world applications in water treatment. The production of calibrated reference particles supports toxicity testing relevant for health agencies. Findings on the persistence of so-called biodegradable plastics call for revised eco-labeling and design policies. Finally, the engagement of social sciences offers insight into behaviors and supports the co-construction of public strategies for plastic pollution management.

3) Research perspectives coming out of the ANR (co)funded projects

Recent multi-institutional research initiatives have outlined a roadmap for advancing plastic pollution science, emphasizing the need for integrated ecological, technological, and regulatory approaches (see BIOMIC project). Future efforts must focus on unraveling the complexity of micro- and nanoplastic pollution across ecosystems, food webs, and human health. A major research frontier involves the fragmentation, degradation, and transformation of plastics in natural environments (as expected in POEM project), particularly in sediments, the water column, and the atmosphere. Understanding these processes is crucial to predicting long-term pollution trends and to designing effective mitigation strategies. Biofouling, UV exposure, sea-air transfer (see recent ATMO-PLASTIC project) microbial activity, and chemical oxidation all influence plastic aging and dispersal. Models must now incorporate vertical transport mechanisms that transfer particles from the surface ocean to deep-sea sediments, as well as air-sea interactions (new project Bubbleplast), which facilitate atmospheric dispersal of microplastics. There is increasing attention on the ecotoxicological impacts of biodegradable plastics, which can fragment and persist in the environment in forms that still pose risks. Their interaction with gut microbiota, effects on metabolic processes, and potential to release chemical additives demand targeted toxicological studies. Likewise, the role of microbial and fungal communities in plastic biodegradation represents a promising frontier for developing bioremediation solutions, yet requires further exploration of degradation pathways under realistic environmental conditions.

A critical and emerging topic is the role of plastics as vectors of pathogens and invasive microorganisms (VECTOPLASTICS). Colonized plastic debris can transport bacteria, viruses, and antibiotic resistance genes across ecosystems. Future research must assess cross-species transmission pathways and potential public health implications, especially in estuaries (PLASTINEST) coastal and aquaculture settings. From an analytical standpoint, improving accelerated aging protocols and detection technologies is essential (New project PLASTIMAR). Advances in spectroscopic and imaging tools have enabled the detection of particles down to the sub-micron scale, and work continues on integrating automated and AI-based identification methods. Simulating environmental weathering in laboratory conditions using UV, mechanical abrasion, or chemical exposure is helping align toxicity tests more closely with field-relevant conditions. These developments are fundamental to the creation of risk indicators and harmonized monitoring tools, which are urgently needed for both research and regulatory purposes.

Research on eco-designed materials and low-impact filtration systems is expanding. New retention processes (like in the new project ECUME) as well as novel materials that are less persistent or easier to degrade—combined with technologies such as bio-inspired marine foams or advanced oxidation processes—open new pathways for sustainable industrial applications and water treatment systems. Their real-world performance and potential unintended effects remain key areas for validation. Citizen science as the one expected in the A2QUA project is playing an increasingly important role in research. Evolving participatory protocols now extend beyond sample collection to include in-field microplastic and nanoplastic analysis, helping democratize data collection and increase public awareness. These approaches contribute meaningfully to large-scale environmental datasets and promote stronger links between science, policy, and society.

In conclusion, tackling plastic pollution requires coordinated, cross-disciplinary research spanning chemistry, oceanography, microbiology, toxicology, modeling, engineering, plastic cycling and degradation studies such as in AOPNANOP as well as social sciences, and law. It involves tracking particles across environmental compartments, assessing their biological impacts, and integrating findings into practical solutions and robust policy frameworks. The intersection of scientific innovation, public engagement, and regulatory development will be key to building effective strategies for prevention, remediation, and sustainable material use.

4- Structuration of the communities:

France has developed a rich and interdisciplinary academic landscape dedicated to research on plastic pollution across freshwater, marine, terrestrial, and atmospheric environments. This research is supported by major universities and national research organizations that contribute to understanding the sources, fate, impacts, and mitigation of plastics and microplastics. Among the leading academic institutions, Aix-Marseille Université, Sorbonne Université, Université de Bordeaux, and Université de La Rochelle have built strong expertise in marine science, ecotoxicology, analytical chemistry, and ocean modeling. Université de Bretagne Occidentale and Université Bretagne Sud are also key players in the study of plastics in coastal and benthic ecosystems. Further inland, Université de Montpellier, Université de Toulouse, Université Gustave Eiffel, Université du Mans, Université Paris-Est Créteil (UPEC), and Université de Lille are involved in interdisciplinary research on the environmental and societal dimensions of plastic pollution. Their contributions span from human exposure, toxicology, and polymer science to socio-economic assessments and environmental law.
This academic network is complemented by the involvement of major national research bodies such as the CNRS, CEA, INRAE, and IRD, all of which contribute through joint research units or cross-institutional programs. Finally, IFREMER is a major partner in the marine component of plastic research, contributing oceanographic data, long-term monitoring efforts, and scientific coordination in national and European projects. The GDR “Polymères et Plastiques dans l’Environnement”, created by the CNRS, plays a central role in federating over 80 research teams across these institutions.

At the European level, significant support has been provided through research and innovation frameworks, including Horizon 2020 and Horizon Europe, which have funded numerous collaborative projects on plastic pollution. These initiatives address topics such as micro- and nanoplastics, biodegradable materials, risk assessment, and the development of advanced monitoring technologies. Many French laboratories have been active participants and beneficiaries of these programs, contributing their expertise in oceanography, chemistry, ecotoxicology, and environmental engineering to multinational research consortia. In parallel, the Joint Programming Initiative (JPI) Oceans has played a leading role in structuring transnational collaboration by launching thematic calls dedicated to microplastics. Projects such as Andromeda, FACTS, HOTMIC, and microplastiX—all of which included French partners—have produced substantial advances in understanding plastic sources, transport mechanisms, degradation pathways, and ecological impacts. These European efforts have strengthened the integration of French research within a broader continental framework, promoted harmonized methodologies, and supported the development of joint scientific tools and shared data platforms that complement national initiatives. At the national level, most research projects on plastics have been funded by the French National Research Agency (ANR), including those conducted in the framework of European initiatives such as JPI Oceans, where French participation is also supported by ANR.

Human activity and society

Research on oceans and coasts is part of an increased interdisciplinary dynamic, in response to the challenges of sustainable development, climate change, biodiversity, and maritime governance. 54 ANR-supported projects address various themes: marine protected areas, coastal risks, surveillance, geopolitics, exploitation of marine resources, maritime archaeology, and environmental justice. They strengthen the links between science and public policies, particularly in overseas territories, and highlight the challenges related to inclusive governance, ecosystem resilience, and equity in resource use. The perspectives call for transdisciplinary research, more engaged and attentive to the social and political dimensions of maritime transformations.

Philippe HRODEJ : Univ. Bretagne Sud et Denis BAILLY : UBO Brest

Scientific Background

Agenda 21 and the international conventions that emerged from the Earth Summit in Rio de Janeiro in 1992 mark the international political recognition of the challenges of sustainable development. From climate change to biodiversity, environmental issues are receiving increasing attention. Research is being called upon to provide a better understanding of natural processes and nature-society interactions, while at the same time encouraging more integrated approaches to the management of environments and areas. Integrated coastal zone management and ecosystem-based management of human activities and environments are shaping the development of public policies at the turn of the 21st century. The complexity of the processes at work and the nature of the issues at stake for human societies also call for more integrated research. In addition to multidisciplinarity, interdisciplinary research is on the increase and there is a strong demand for research in the social sciences. At the same time, research related to the ocean and coastal areas is developing strongly. Between coastal risks, pollution, biodiversity conservation and the sustainable blue economy, there is a growing body of research on protected areas, interactions between human activities and the environment, maritime and coastal cultural heritage, as well as technological innovation and the very way research is conducted. There is a strong demand for research that is more in touch with society through transdisciplinarity, peer review and forward-looking modelling in support of public policy. At the same time, as environmental issues become ever more pressing and complex, the field of investigation of social sciences and societal issues has continued to expand.

Main contribution of the French communities through ANR cofunds

Most of humanity has developed on the shores of the oceans. But island populations offer a special case study: they are undoubtedly more threatened by rising sea levels, but they are also more vulnerable economically. The case of French Polynesia, where more than a hundred islands are spread over a 2,000km stretch of sea (Armilit or Atolls project), provides an illuminating case study of the rise in human concentration on a hub such as Papeete and the ebb towards the offshore islands once saturation has been reached. This raises the problem of monitoring the public service and evaluating these migrations. Clearly, this phenomenon makes it a little more difficult to maintain cohesion between different groups in the overseas territories, which are already undermined by ethnic or racial "frontiers" that do not seem to be disappearing, just like the ambiguity that we are struggling to resolve between equality for all and the particularities that need to be respected. The specific nature of these territories in terms of their remoteness from the central State, their history and their complex cohabitation, clashes with this republican equality, making the equation an arduous one. The Prodisdom programme would undoubtedly have benefited from being analysed in the light of recent events in New Caledonia. Beyond land, the sea brings its own set of threats. The increase in maritime traffic, the fact that criminals of all kinds can use these liquid highways with impunity and blend in with all kinds of vessels criss-crossing the oceans, means that we need to refine the necessary intelligence from a vessel approaching the coast. The AIS, which certainly provides a real-time picture of the scale of the trade, the routes followed, the destinations and the types of vessel, is only one criterion of this intelligence, which needs to be enriched by other elements drawn from the usual process of multiplying the sources (from other databases), and processing them within a new database. A tool of this kind, called ScanMaris, has been tested on the French Mediterranean coast as part of the Day River project, linking a chain of companies or organisations involved, from data supplier to designer to user. Identifying has always been a sailor's main concern, from the number of sails on the horizon to the shape of a fast-approaching aircraft. Identifying in order to adapt our response remains the basis of any surveillance of the sea from the sea as well as from land. But those, at all levels, who are responsible for maintaining order on the seas know that technology and intelligence reach their limit when the law does not follow with its necessary jurisprudence, when the "services" are not able to coordinate their efforts integrated in a millefeuille between local, regional, national and European levels. Having already a clear vision of the challenge of controlling the seas, and the difficulty of reconciling this with the freedom linked to the Law of the Sea, the Genoarchéa project set out to reflect on all these components. Of all the dimensions linked to the oceans, safety is an aspect that now occupies a crucial place. The Black Sea is particularly acute in this respect (Boom project) where, in an anxiety-provoking context, the decisions of the European Union are awaited in the face of regional desires and Russian or Turkish appetites. It is notable that knowledge is intimately linked to security. In a similar vein, the Alarm project has been able to implement innovative extended-range laser imaging technologies for maritime surveillance, in addition to the usual optical means for better detection of small signals left by craft, for example. In the context of asymmetric warfare, which is very present at sea, the gains are considerable. Seeing, even perceiving, is as essential as not being seen. The Ramses project has made it possible to work on acoustic radiation so as to reduce the signature of a ship by reducing the waves created by the stiffeners inside its hull. This will improve stealth. The Digital Ocean project has produced seabed editing software to recreate an underwater environment in 3D: a video game, of course, but also an important decision-making aid in the fields of prospecting and accidentology. But technology alone is not capable of providing solutions to maritime risks. The sea, maritime territories or the zone, and crime in all its many facets, give rise to a maze of legal rules that are rapidly creating obstacles to intervention by European states at sea. We need to take stock of all these rules and assess their impact on identified problems in order to provide better solutions.

Maritime areas have a multiplicity of approaches: control, regulation, pacification, preservation, they are also areas of knowledge for mankind far from having been fully explored, far from an exhaustive inventory. The Black Sea, which is now once again the Pont-Euxin, is also a little-known land of archaeological conquest (Livingstone project and the Pont-Euxin). And without going back in time, the Chinese seas were also the focus of attention during the modern era, when after the great expeditions of Zheng He in the 15th century, it was agreed that the European presence had crushed what remained of the Chinese's maritime ambitions. But on the sea, one experience does not destroy the previous one, it combines with it. This was the case with the thousands of junks that set sail for Manila, maintaining trade links with the vessels of the various East India companies (Xpress project). In an unexpected way, archaeology can come to the rescue of tomorrow's steels, particularly those that will be used to preserve contaminated materials. The Arcor project looked at the corrosion mechanisms of archaeological objects over several centuries.

Research perspectives

This brief review of a small sample of projects funded by the ANR over the last 20 years shows the diversity and richness of the issues related to human activities, in the broadest sense, and of the contributions made by the human and social sciences. These questions are evolving both in number and complexity. More than ever, the disciplines involved must continue to be mobilised, and those that have received little support must receive particular attention.
In terms of biodiversity conservation, the benefits of marine protected areas have been amply demonstrated. At a time when quantitative targets are dominating the international debate - 30% in EEZs and the high seas by 2030, and 10% under strong or strict protection - the challenge for research is to focus on the qualitative aspects, i.e. the effectiveness of protected areas, the resources dedicated to protection and the mobilisation of stakeholders in the maritime world. Effective protection also involves networks of marine protected areas, which requires a better understanding of the connectivity between the different areas, as well as governance on a broader, more inclusive scale. The tensions between conservation and use of the marine environment, social mobilisation in favour of the environment, strategies to weaken environmental policies and political responses are all areas of study for a wide range of social science research. Restoring degraded ecosystems raises new questions that go beyond mere protection.

Coral reefs, coastal wetlands, seagrass beds and mangroves provide a range of services and make a major contribution to the biological diversity of the marine environment. They offer nature-based solutions to a number of problems. Protecting them, and where possible restoring them, is a key issue, whether for coastal protection, carbon sequestration, resource provision or more cultural benefits.

Blue growth, conservation, deep-sea mining and the development of marine genetic resources all raise questions about ocean governance. We need to build forms of maritime democracy at both local and multilateral levels. Questions of social justice, or blue justice, such as the recognition of the rights of local populations or traditional activities, are at the heart of many of the tensions we are observing. The operationalisation of the concepts of the common heritage of mankind, the common ocean and the sharing of benefits also raises many questions.

The effects of climate change on oceans and coasts will be increasingly marked, both for ecosystems and coastal areas. As far as coastal risks are concerned, various strategies have been put in place over the last two decades. Tools exist to monitor natural phenomena and the vulnerability of coastal societies. Making them available to local players must go hand in hand with an analysis of feedback.

Against a backdrop of fragmented global governance and heightened competition, the ocean is increasingly a geostrategic challenge. Whether it's a question of international trade, navigation safety, infrastructure protection or illegal activities, international cooperation must be strengthened to ensure clean and safe seas from the coast to international waters. A better knowledge and understanding of the history of the various maritime areas, powers and activities, of conflicts and their resolution, of cooperation, etc., is essential to ensure that the seas are safe and clean.

All of these issues raise questions related to society: players, representations, social movements, economic interests, rules, institutions and governance. All the disciplines of the humanities and social sciences must be called upon to examine these issues using their own concepts and methods. Interdisciplinarity within the social sciences should also be strongly encouraged in future research, as should research combining social sciences and natural sciences on subjects where this is relevant. Research that is more directly linked to society, cross-disciplinary or in support of debates or public policies, without shying away from controversy.

Philippe HRODEJ et Denis BAILLY - Activités humaines et société

Introduction

L’Agenda 21 et les conventions internationales issues du sommet de la terre de Rio de Janeiro en 1992 marquent la reconnaissance politique à l’échelle internationale des enjeux du développement durable. Qu’il s’agisse de changement climatique ou de biodiversité, les questions environnementales font l’objet d’une attention de plus en grande. La recherche est convoquée pour une meilleure compréhension des processus naturels, des interactions nature-société en même temps que des approches plus intégrées de la gestion des milieux et des espaces sont encouragées. Gestion intégrée mer et littoral, gestion intégrée des zones côtières, gestion écosystémique des activités humaines et des milieux structurent l’évolution des politiques publiques au tournant du XXIème siècle. La complexité des processus à l’œuvre et la nature des enjeux pour les sociétés humaines appellent des recherches elles aussi plus intégrées. Au-delà de la pluridisciplinarité, les recherches interdisciplinaires se multiplient et une forte attente s’exprime vis-à-vis des recherches en sciences sociales. Dans le même temps, les recherches liées à l’océan et aux littoraux se développement fortement. Entre risques côtiers, pollutions, conservation de la biodiversité et économie bleue durable, les travaux de recherche se multiplient sur les aires protégées, les interactions entre activités humaines et environnement, les patrimoines culturels maritimes et côtiers mais aussi l’innovation technologique et la manière même de faire la recherche. Une forte attente s’exprime vis-à-vis d’une recherche plus en prise avec la société au travers de la transdisciplinarité, des expertises collégiales ou de modélisations prospectives en support au politiques publiques. Dans le même temps, et alors que les questions environnementales deviennent de plus en plus pressantes et les enjeux complexes, le champ d’investigation des sciences sociales et questions sociétales n’a cessé de s’élargir.  

Avancées de la recherche

La majeure partie de l’humanité se développe sur les rivages bordiers des océans. Mais les populations insulaires offrent une étude particulière, sans doute sont-elles plus menacées par la montée des eaux mais aussi plus vulnérables sur le plan économique. Le cas de la Polynésie française où plus d’une centaine d’îles sont réparties sur un espace maritime de 2.000km (projet Armilit ou Atolls) peut être un objet d’étude éclairant de la montée en puissance de la concentration humaine sur un hub comme Papeete et le reflux vers les îles au large une fois le degré de saturation atteinte. Se pose alors le problème du suivi du service public et de l’évaluation de ces migrations. D’évidence, ce phénomène complique un peu plus le maintien d’une cohésion entre différents groupes dans les territoires ultramarins, déjà minés par les « frontières » ethniques ou raciales qui ne semblent pas disparaître, tout comme de cette ambiguïté que l’on peine à solutionner entre égalité pour tous et les particularismes qu’il convient de respecter. La spécificité de ces territoires par rapport à leur éloignement de l’Etat central, par rapport à leur histoire et à ces cohabitations complexes, s’oppose à cette égalité républicaine, rendant l’équation ardue. Le programme Prodisdom aurait sans doute gagné à être analysé au vu des événements survenus en Nouvelle-Calédonie récemment.

Au-delà des terres émergées, la mer apporte son lot de menaces. L’augmentation du trafic maritime, le fait que des criminels de tous genres puissent emprunter en toute impunité ces autoroutes liquides et se fondre aux bâtiments de toutes sortes sillonnant les océans, nécessitent d’affiner le renseignement que l’on se doit d’obtenir de la part d’un navire approchant des côtes. L’AIS qui fournit certes une situation en temps réel de l’importance du commerce, des routes suivies, des destinations et des types de bâtiments n’est qu’un critère de ce renseignement qui doit s’enrichir d’autres éléments puisés selon un processus habituel de multiplication des sources (tirées d’autres bases de données), et de dépouillements de celles-ci au sein d’une nouvelle base de données. Un tel outil, baptisé ScanMaris, a été éprouvé sur les côtes méditerranéennes françaises dans le cadre du projet Day River, permettant de mettre en rapport une chaîne d’entreprises ou d’organismes concernés, du fournisseur de données, au concepteur et à l’utilisateur. Identifier a toujours été la grande préoccupation d’un navigateur, du nombre de voiles à l’horizon à la forme d’un avion en rapprochement rapide. Identifier pour adapter sa réaction reste la base de toute surveillance de la mer depuis la mer comme depuis la terre. Mais ceux, à tous les niveaux, qui sont chargés de maintenir l’ordre sur les mers savent que la technologie et le renseignement atteignent leur limite dès lors que la loi ne suit pas avec sa nécessaire jurisprudence, dès lors que les « services » ne sont pas en mesure de coordonner leurs efforts par intégrés dans un millefeuille entre les échelons locaux, régionaux, nationaux et européens. Avoir déjà une vision claire de la gageure qu’est le contrôle des mers, la difficile conciliation de celui-ci avec la liberté liée au droit de la mer, le projet Genoarchéa s’est proposé de réfléchir sur toutes ces composantes. De toutes les dimensions liées aux océans, la sécurité est un aspect qui tient une place désormais cruciale. La mer Noire atteint à ce titre un degré d’acuité particulier (projet Boom) où, dans un cadre anxiogène, sont attendues les décisions de l’Union européenne confrontées aux volontés régionales et à l’appétit russe ou turc. Il est notable que la connaissance est intimement liée à la sécurité. Dans une semblable logique, le projet Alarm a pu mettre en place des technologies innovantes d’imagerie laser à portée étendue pour la surveillance maritime qui s’ajoutent aux moyens usuels optiques pour mieux repérer de petits signaux laissés par des embarcations par exemple. Dans le cadre d’une guerre asymétrique, très présente sur mer, le gain est considérable. Voir, percevoir même est indispensable, autant que n’être pas vu. Le projet Ramses a permis de travailler sur le rayonnement acoustique de façon à réduire la signature d’un bâtiment en jouant sur la réduction des ondes créées par les raidisseurs internes à sa coque. De quoi améliorer la furtivité. Le projet Digital Ocean a réalisé un logiciel d’édition de fonds marins pour recréer un environnement sous-marin en 3D : un jeu vidéo certes mais aussi une aide à la décision importante dans les domaines de la prospection ou de l’accidentologie. Mais la technologie n’est pas seule capable d’apporter des solutions aux risques maritimes. La mer, territoires maritimes ou Zone, la criminalité avec ses multiples facettes engendrent un mille-feuilles de règles juridiques qui créent rapidement des entraves aux interventions des Etats européens en mer : recenser l’ensemble de ces règles, les évaluer quant à leurs impacts sur des problèmes identifiés pour mieux apporter de solutions.

Les espaces maritimes ont vocation à multiplier les types d’approches : contrôle, régulation, pacification, préservation, ils sont également des zones de connaissance pour l’homme loin d’avoir été entièrement explorés, loin d’un inventaire exhaustif. Redevenant le Pont-Euxin, la mer Noire est aussi une terre de conquête archéologique méconnue (projet Livingstone et Pont-Euxin). Et sans autant reculer dans le temps, les mers chinoises sont aussi l’objet d’attention durant l’époque moderne où après les grandes expéditions de Zheng He au XVe siècle, on a pu convenir que la présence européenne avait écrasé ce qui restait de velléités maritimes des Chinois. Mais, sur mer, une expérience ne détruit pas la précédente, elle se conjugue avec elle. Cela été le cas de ces milliers de jonques à prendre la route de Manille, à entretenir des liens commerciaux avec les vaisseaux des différentes compagnies des Indes orientales (projet Xpress). De façon inattendue, l’archéologie peut venir au secours des aciers de demain, ceux notamment qui serviront à conserver des matières contaminées. Le projet Arcor s’est ainsi intéressé aux mécanismes de corrosion des objets archéologiques sur plusieurs siècles.

Conclusion et axes futurs de recherche

Cette brève revue d’un échantillon réduit de projets financés par l’ANR au cours des 20 dernières années montre la diversité et la richesse des questionnements liés aux activités humaines, au sens large, mais aussi des contributions des sciences humaines et sociales. Ces questions évoluent à la fois en nombre et en complexité. Plus que jamais, les disciplines mobilisées doivent continuer de l’être et celles qui ont été peu soutenues doivent faire l’objet d’une attention particulière.

En matière de conservation de la biodiversité, les avantages des aires marines protégées ont été largement démontrés. Dans un moment politique où les objectifs quantitatifs dominent le débat à l’échelle internationale, 30% en 2030 dans les ZEE et en haute mer et 10% en protection forte ou stricte, l’enjeu pour la recherche porte sur les dimensions qualitatives que sont l’efficacité des aires protégées, les moyens dédiés à la protection et la mobilisation des acteurs du monde maritime. Une protection efficace passe aussi par des réseaux d’aires marines protégées, supposant de mieux comprendre la connectivité entre les différents espaces mais aussi une gouvernance à des échelles plus larges et plus inclusives. Les tensions entre conservation et usages du milieu marin, les mobilisations sociales en faveur de l’environnement mais aussi les stratégies d’affaiblissement des politiques environnementales et les réponses politiques sont autant de champs d’étude pour un large éventail de recherches en sciences sociales. Au-delà de la simple protection, la restauration des écosystèmes dégradées ouvre de nouvelles questions.

Les récifs coralliens, les zones humides littorales, les herbiers marins et les mangroves fournissent un éventail de services et contribuent fortement à la diversité biologique du milieu marin. Ils offrent des solutions fondées sur la nature à plusieurs problématiques. Leur protection, et lorsque cela est possible leur restauration, est un enjeu que ce soit pour la protection du littoral, la séquestration de carbone, la mise à disposition de ressources ou des bénéfices plus culturels.

Croissance bleue, conservation, exploitation minière des grands fonds ou valorisation des ressources génétiques marines, tous ces sujets interrogent la gouvernance de l’océan. Des formes de démocratie maritime sont à construire tant au niveau local que multilatéral. Les questions de justice sociale, ou justice bleu, telles que la reconnaissance des droits des populations locales ou des activités traditionnelles sont au cœur de nombre des tensions que l’on observe. L’opérationnalisation des notions de patrimoine commun de l’humanité, d’océan commun et de partage des avantages soulèvent aussi de nombreuses interrogations.

Les effets du changement climatique sur l’océan et les littoraux seront de plus en plus marqués tant sur les écosystèmes que sur les territoires côtiers. Pour ce qui est des risques côtiers diverses stratégies ont été mise en place depuis deux décennies. Les outils de suivi des phénomènes naturels et de la vulnérabilité des sociétés côtières existent. Leur mise à disposition auprès des acteurs locaux doit aller avec une analyse des retours d’expérience. 

Dans un contexte de fragmentation de la gouvernance globale et de concurrences exacerbées, l’océan porte de plus en plus d’enjeux géostratégiques. Qu’il s’agisse de commerce international, de sécurité de la navigation, de protection des infrastructures ou d’activités illégales, la coopération internationale devra être renforcée pour des mers propres et sûres de la côte jusque dans les espaces internationaux. Une meilleure connaissance et appropriation de l’histoire des différents espaces, pouvoirs et activités maritimes, des conflits et de leur résolution, des coopérations.

L’ensemble de ces sujets soulève des questions en lien avec la société : acteurs, représentations, mouvement sociaux, intérêts économiques, règles, institutions ou gouvernance. Toutes les disciplines de sciences humaines et sociales doivent être convoquées pour interroger ces enjeux à partir de leurs concepts et méthodes. L’interdisciplinarité au sein des sciences sociales doit aussi être fortement encouragée dans les recherches à venir, tout autant que les recherches associant sciences sociales et sciences de la nature sur les sujets pour lesquels cela est pertinent. Les recherches plus directement en lien avec la société, transdisciplinaires ou en appui aux débats ou aux politiques publiques, sans esquiver les controverses.

CLIMATE AND THE OCEAN

The ocean regulates the climate by storing heat and CO2 but suffers major effects of climate change (acidification, rising waters, extreme events). 102 ANR projects have led to technological advances in AI modeling and deep sensors, as well as progress in knowledge about marine biodiversity, predictions of algal blooms, and the contribution of rivers (pollutants and carbon). This work supports climate policies (SDGs 13 and 14) and calls for strengthening international and interdisciplinary scientific cooperation to better predict future impacts on the oceans, involving participation in UN working groups such as the IPCC.

Sabrina Speich : ENS PSL Paris and Patrick Monfray : CNRS IPSL

1. Scientific Background

The ocean is a fundamental component of the Earth’s climate system, exerting control over energy balance, atmospheric circulation, and biogeochemical cycles. Covering approximately 71% of the Earth’s surface and storing more than 90% of the excess heat from anthropogenic warming (von Schuckmann et al., 2023; Cheng et al., 2020), the ocean acts as a global heat reservoir that moderates climate variability on seasonal to millennial timescales (Stocker et al., 2013). Ocean circulation, through both wind-driven gyres and the density-driven meridional overturning circulation (MOC), redistributes heat and carbon across latitudes, thereby shaping regional climates and influencing extreme weather patterns (Buckley and Marshall, 2016).

Beyond its role as the major anthropogenic heat sink and distributor, the ocean plays a crucial part in the carbon cycle. It currently absorbs roughly 25% of human-induced CO₂ emissions (Friedlingstein et al., 2024), largely through physical (solubility pump) and biological (biological pump) mechanisms (DeVries et al., 2017). However, this critical buffering capacity is not without consequences, as rising CO₂ levels lead to ocean acidification, with potential disruptions to marine ecosystems and carbonate chemistry (Gattuso and Hansson, 2011). Additionally, deoxygenation and changes in nutrient cycling induced by warming and stratification shifts pose risks to biodiversity and ecosystem services (Bindoff et al., 2019; IPCC, 2021).

Climate change is also driving significant changes in global and regional sea levels, primarily due to ocean thermal expansion and the melting of glaciers and ice sheets (IPCC, 2021). The accelerating mass loss from the Greenland and Antarctic ice sheets contributes to both global mean sea level rise and regional variations that disproportionately affect certain coastal regions (Oppenheimer et al., 2019). Meanwhile, extreme ocean events such as marine heatwaves (Frölicher et al., 2018; Capotondi et al., 2025), intensified tropical cyclones (Knutson et al., 2020) and other extreme events are becoming more frequent, with profound implications for ecosystems, human societies, and climate stability (IPCC, 2021).

Despite significant advances in ocean observation, modeling, and theoretical understanding, key uncertainties remain regarding the response of oceanic processes to climate change. Addressing these knowledge gaps is crucial not only for improving climate projections but also for developing informed mitigation and adaptation strategies.

A first major challenge in ocean-climate research lies in understanding ocean circulation and its variability in a warming world. Large-scale currents such as the Atlantic Meridional Overturning Circulation (AMOC) play a critical role in redistributing heat and modulating global climate patterns, yet their stability under anthropogenic forcing remains uncertain (Weijer et al., 2019). The slowdown of the AMOC, if confirmed, could trigger profound climate shifts, particularly in Europe and North America. At finer scales, the role of mesoscale and submesoscale processes in controlling heat and carbon transport remains insufficiently constrained (McWilliams, 2016), requiring further observational and modeling efforts to improve climate predictions.

Another fundamental issue concerns the ocean’s role in carbon sequestration and its evolving efficiency in response to global change. Warming and increasing stratification are altering the vertical transport of carbon and nutrients, with potential repercussions for biological productivity and CO₂ uptake (De Vries et al., 2023; Landschützer et al., 2016). The interplay between ocean acidification, deoxygenation, and ecosystem shifts (Boyd et al., 2019) raises concerns about the resilience of marine food webs and the sustainability of fisheries, which are already experiencing climate-induced redistribution (Cheung et al., 2010). Additionally, uncertainties remain regarding feedbacks between ocean biogeochemistry and atmospheric CO₂ levels, particularly under future emission scenarios (Riebesell and Gattuso, 2015).

Changes in sea level and cryosphere-ocean interactions constitute another major research priority, with direct implications for coastal populations. Improving projections of ice sheet melting and its contribution to sea level rise is essential for assessing future coastal risks (Pritchard et al., 2012). Regional variations in sea level, influenced by ocean dynamics, gravitational effects, and land subsidence, complicate risk assessments and demand a more refined understanding of local-scale processes (Slangen et al., 2014). Additionally, the increasing occurrence of compound flooding events, where storm surges coincide with rising baseline sea levels, poses new challenges for coastal resilience planning (Kopp et al., 2017).
The intensification of extreme events linked to oceanic changes is also an area of growing concern. Marine heatwaves, characterized by prolonged periods of anomalously high sea surface temperatures, have devastating effects on marine ecosystems, including coral bleaching, shifts in species distributions, and disruptions to fisheries (Oliver et al., 2019). Understanding the drivers of these events and their interactions with atmospheric circulation patterns is crucial for improving predictability and mitigation strategies. Moreover, changes in ocean stratification and heat uptake influence tropical cyclone intensity, with evidence suggesting that warmer ocean conditions contribute to stronger and more destructive storms (Bhatia et al., 2019).

To address these challenges, advancements in ocean observation and modeling capabilities are critical. Expanding global ocean monitoring networks, such as Argo and Biogeochemical-Argo (Roemmich et al., 2019), will provide essential data for tracking long-term trends in ocean temperature, salinity, and biogeochemical properties. Integrating these observations into coupled Earth system models will enhance climate projections, while improved data assimilation techniques will refine our ability to reconstruct ocean state variability (Brassington et al., 2015). Recent developments in artificial intelligence and machine learning also hold promise for optimizing model parameterization and reducing uncertainties in ocean-climate interactions (Reichstein et al., 2019).

Beyond the physical and biogeochemical dimensions, understanding the socio-economic and ecological impacts of ocean change is equally imperative. Climate-driven shifts in fishery distributions are already affecting food security and livelihoods, particularly in developing nations dependent on marine resources (Cheung et al., 2010). Conservation strategies must adapt to these shifts, integrating dynamic marine protected areas and ecosystem-based management approaches to safeguard biodiversity under changing environmental conditions (Lubchenco and Gaines, 2019). Additionally, the socio-economic consequences of sea level rise, including infrastructure losses, migration, and geopolitical tensions, require urgent interdisciplinary research to develop sustainable adaptation policies (Hauer et al., 2020).
The ocean is both a driver and a responder to climate change, regulating the Earth's energy balance, carbon cycle, and extreme events. However, the accelerating pace of anthropogenic perturbations introduces new uncertainties and challenges that demand urgent scientific attention. By advancing observational capabilities, refining numerical models, and fostering interdisciplinary collaboration, the scientific community can improve climate predictions and inform policy decisions for sustainable ocean and climate management. The integration of physical, biogeochemical, and socio-economic research will be crucial in addressing the complex and interlinked challenges posed by a changing ocean.

Anthropogenic activities affect not only the physical conditions of the oceans (temperature, salinity, sea-ice, currents, sea level, etc…) but the whole biological system, from the cycling of carbon and nutrients to marine diversity and resources. It is due not only to climate change driven by greenhouse gases but also to the increased flow of material bring by rivers or atmospheric deposition. Beyond providing marine resources and biodiversity, oceans regulate climate by absorbing heat and excess greenhouse gases (one third of anthropogenic CO₂ emissions).

In the last 20 years, main advancements had been made by using new observing system as automatic buoys, gliders, towed and in-situ sensors, genetic speciation on-board or in-lab, extended assimilation of physical, geochemical and chlorophyll data into process-based models. These latter now couple ocean physics to carbon cycle, acidification, oxygen and trophic levels and allow from coast to deep ocean i) reconstruction over the last century, ii) real time analysis and forecast, iii) investigation of different impact scenarios of anthropogenic activities.

Recognizing these gaps and challenges, the French Agence Nationale de la Recherche (ANR) has funded a range of research projects aimed at advancing knowledge of ocean-climate interactions. These projects have leveraged interdisciplinary approaches, combining observational campaigns, high-resolution modeling, and theoretical developments to improve predictions of climate variability and assess the long-term impacts of anthropogenic forcing on oceanic and atmospheric processes. By fostering collaboration between national and international research teams, ANR-funded projects have made significant contributions to understanding the role of the ocean in climate regulation, the mechanisms driving extreme events, and the socio-economic implications of ocean-climate change. The results from these projects provide crucial insights for climate mitigation and adaptation strategies, contributing to the development of policy-relevant climate services.

2. Main Contributions of the French Communities through ANR (co)funding

2.1 Scientific Progress: Cutting-edge Science

Understanding Climate Change: Past, Present, and Future

Reconstructing past climate variability provides a crucial benchmark for improving future climate projections. Ice-core records and marine sediment analyses have revealed long-term climate cycles and abrupt transitions that shaped Earth's climate history. By integrating paleoclimatic data with numerical simulations, researchers have refined estimates of climate sensitivity, identifying thresholds beyond which irreversible changes occur. Notably, investigations of past high-CO₂ periods have confirmed the presence of significant polar amplification, a phenomenon that has direct implications for modern and future climate scenarios (PICC).

The reconstruction of past monsoon variability has provided new insights into the interactions between atmospheric circulation and oceanic conditions over long timescales. Sedimentary records from the Bay of Bengal have demonstrated that Indian monsoon strength fluctuates in response to orbital forcing, volcanic activity, and greenhouse gas concentrations. This research has deepened our understanding of how the monsoon system reacts to past warming events and has implications for predicting monsoonal behavior under continued anthropogenic influence (MONOPOL).

Decadal to centennial-scale climate variability is driven by complex interactions between oceanic and atmospheric processes. Long-term climate reconstructions have highlighted the role of ocean circulation, particularly the Atlantic Meridional Overturning Circulation (AMOC), in modulating past climate fluctuations. By disentangling internal climate oscillations from externally forced trends, researchers have improved attribution studies, which are key to distinguishing human-induced climate change from natural variability (MORDICUS).

High-latitude climate reconstructions have confirmed the strong coupling between atmospheric and oceanic processes in shaping regional and global climate states. Ice-core analyses and historical climate records from Greenland indicate that Arctic climate sensitivity is closely linked to shifts in atmospheric circulation patterns. Past warming episodes in the Arctic have been associated with significant ice sheet retreat and rising sea levels, underscoring the region’s vulnerability to climate change. Furthermore, reconstructions of volcanic activity have shown that eruptions play a significant role in short-term climate perturbations, influencing atmospheric circulation over multiple decades (GREENLAND).

Understanding the interplay between ocean-atmosphere variability and climate extremes has been advanced through studies of past El Niño-Southern Oscillation (ENSO) dynamics. Observations and modeling efforts have shown that short-term atmospheric fluctuations, such as wind bursts, can have a disproportionate influence on the formation of El Niño events. These results challenge previous assumptions about ENSO predictability and emphasize the importance of high-resolution modeling in climate forecasting (METRO).

Detailed sedimentary archives have been essential in reconstructing past changes in ocean circulation and their impact on global climate. Marine records have confirmed that past weakening of the AMOC was linked to major climatic disruptions, including cooling episodes in the North Atlantic and changes in precipitation patterns in the tropics. These findings contribute to ongoing discussions about the stability of the AMOC in response to present-day warming and its potential tipping points (ARCHANGE).

Advancements in paleoclimate coring techniques have also played a critical role in refining past climate reconstructions. The development of high-resolution coring methods has enabled the extraction of continuous sediment records that provide unparalleled insights into past oceanic and atmospheric conditions. These advances have facilitated the reconstruction of multi-millennial climate variations and have been instrumental in improving the calibration of climate models (CLIMCOR).

The collective results of these research efforts underscore the importance of integrating paleoclimate data into climate projections. By leveraging long-term records of climate variability, researchers have improved constraints on future climate evolution and provided essential benchmarks for assessing the magnitude and pace of anthropogenic climate change.

Ocean Dynamics

Ocean circulation is a fundamental component of the Earth's climate system, regulating heat transport, nutrient distribution, and carbon sequestration. Recent research has significantly improved our understanding of the interactions between large-scale ocean currents, mesoscale eddies, and atmosphere-ocean exchanges. The influence of mesoscale eddies in redistributing ocean heat and modulating the global energy balance has been increasingly recognized, leading to the development of high-resolution numerical models that better capture these fine-scale processes. By refining eddy parameterizations in climate models, researchers have been able to enhance the representation of energy transfer across different oceanic scales, improving long-term climate projections (RETRO).

The role of tropical cyclones in driving ocean-atmosphere interactions has been extensively examined, with studies highlighting their capacity to induce deep ocean mixing and facilitate heat redistribution. By analyzing cyclone-induced heat flux anomalies, researchers have identified how these extreme weather events contribute to upper ocean warming, altering thermocline stability and regional climate dynamics. These findings have improved our capacity to simulate the influence of cyclonic activity on climate variability and provided key insights into future cyclone behavior under a warming climate (TROCODYN).

Advancements in the representation of oceanic turbulence have led to significant improvements in climate model accuracy. Research has revealed that unresolved sub-mesoscale turbulence plays a crucial role in ocean heat uptake and transport, necessitating the development of refined turbulence parameterizations. The inclusion of more sophisticated mixing schemes has enabled better simulations of oceanic vertical structure, reducing biases in sea surface temperature predictions and improving the reliability of climate projections (CONTACTS).

Ocean variability on interannual to decadal timescales is strongly influenced by large-scale circulation patterns, such as the Atlantic Meridional Overturning Circulation (AMOC). Studies have confirmed that variations in AMOC strength are linked to significant climatic shifts, including abrupt temperature changes in the North Atlantic and disruptions in tropical precipitation patterns. Research efforts have focused on quantifying AMOC’s response to external forcing and internal variability, contributing to a better understanding of its potential weakening in response to anthropogenic climate change (SouthernCross).

Ocean-Land Interactions, Including River Deltas

Coastal and riverine systems are highly dynamic environments shaped by both natural processes and human activities. Research has advanced our understanding of how climate change influences sea-level rise, sediment transport, and deltaic stability, with particular focus on the resilience of coastal infrastructures. Studies have examined the effectiveness of dike systems and nature-based solutions in mitigating flood risks, balancing engineering solutions with ecological restoration to enhance long-term coastal protection. These efforts have provided key recommendations for sustainable adaptation strategies that integrate environmental, economic, and social considerations (DIGUES).

Climate-induced migration from deltaic regions has been extensively analyzed, revealing complex socio-environmental feedbacks that influence population displacement and urban adaptation. Investigations into the long-term evolution of delta systems have shown how sedimentary changes, driven by both natural and anthropogenic factors, shape coastal habitability. Historical records and geological reconstructions have provided crucial insights into past adaptation strategies, informing contemporary policies for climate-resilient urban development (MOVINDELTAS).

Studies of past coastal landscapes have further enriched our understanding of how environmental changes have shaped human settlements over time. By integrating archaeological, sedimentological, and climate data, researchers have reconstructed historical shoreline dynamics, highlighting the role of climate variability in shaping coastal communities. These interdisciplinary approaches have provided essential context for present-day challenges in managing fragile coastal environments (ARMILIT, PALEOMED).

Extreme Events

The increasing frequency and intensity of extreme weather events present a critical challenge in climate research, necessitating improved prediction and risk assessment methods. Advances in high-resolution modeling have refined our ability to simulate hurricanes, heatwaves, and heavy precipitation, enabling a more accurate understanding of their underlying drivers. Studies have revealed key feedback mechanisms that regulate extreme event severity, particularly interactions between ocean heat content, atmospheric moisture fluxes, and large-scale circulation patterns. These insights have provided crucial data for improving forecast models and developing adaptation strategies for regions prone to extreme climate events (REMEMBER).

In the Mediterranean, a region particularly sensitive to climate variability, refined projections of extreme hydrometeorological events have strengthened our capacity to anticipate flash floods, prolonged droughts, and temperature extremes. Research has emphasized the importance of fine-scale atmospheric processes and land-sea interactions in modulating these events, leading to enhanced early warning systems and risk management strategies. By incorporating observational data and numerical simulations, studies have improved our ability to assess how regional climate extremes may evolve under future warming scenarios (IODA-MED).

Tropical cyclone variability has been a focal point of research, as these systems play a crucial role in global heat redistribution and are expected to intensify in a warming climate. Investigations into the influence of oceanic conditions on cyclone development have demonstrated that rising sea surface temperatures and altered wind shear patterns significantly impact cyclone intensity and trajectories. Research has also explored how cyclone-induced ocean mixing affects regional heat budgets, providing new insights into feedback loops between extreme weather events and long-term climate dynamics (TROCODYN).

Improved observational and modeling techniques have allowed for a more comprehensive understanding of the compound effects of extreme events, particularly when multiple hazards interact. Studies have examined how sequential or simultaneous climate extremes—such as successive storms or concurrent heatwaves and droughts—compound societal and ecological vulnerabilities. These findings have informed policy recommendations for integrated risk management, emphasizing the necessity of multi-hazard early warning systems and cross-sectoral adaptation planning (REMEMBER).

These progresses in extreme event research have provided critical knowledge for mitigating climate-related disasters. By refining predictive capabilities, enhancing impact assessments, and developing early warning frameworks, scientists have contributed to more resilient climate adaptation strategies, particularly for communities facing increasing exposure to extreme weather hazards.

Observing Techniques

The evolution of observational techniques has fundamentally transformed our ability to monitor ocean-climate interactions and improve long-term climate predictions. High-precision ice-core drilling has enabled more detailed reconstructions of past climate variability, offering valuable insights into atmospheric composition, temperature fluctuations, and ocean-atmosphere feedbacks over millennia. By refining extraction methods and analytical procedures, researchers have produced high-resolution paleoclimate records that provide critical benchmarks for evaluating climate models and understanding long-term climate trends (SUBGLACIOR).

Satellite remote sensing and in situ ocean monitoring have significantly improved our capacity to observe sea surface temperatures, salinity gradients, and ice-sheet dynamics in real time. Advanced oceanographic sensors deployed on autonomous platforms have allowed for the continuous collection of oceanic and atmospheric data, enhancing our ability to monitor large-scale climate variability. These advancements have also led to improvements in data assimilation techniques, strengthening the accuracy of climate models and their ability to capture transient climate events (IODA-MED).

Seismic wave analysis has been adapted to study Arctic ice structures, providing new methodologies for assessing ice thickness variability and stability under changing climatic conditions. By using seismic imaging to investigate subglacial environments and sea ice dynamics, researchers have developed innovative approaches to track ice mass changes and their contributions to sea-level rise. These efforts have provided a more refined understanding of how polar ice sheets respond to oceanic and atmospheric warming, with direct implications for future climate projections (WaveSIMM).

The integration of real-time ocean-atmosphere datasets into climate forecasting models has significantly enhanced the predictability of extreme weather events, particularly in coastal regions vulnerable to rising sea levels and increasing storm intensity. By combining high-resolution observational data with advanced numerical simulations, scientists have improved early warning systems for extreme weather phenomena such as tropical cyclones, marine heatwaves, and storm surges. These advancements have been instrumental in strengthening disaster preparedness and informing climate adaptation strategies at regional and global scales (CLIMCOR).

These innovations in observational methodologies have expanded our capacity to understand, monitor, and predict ocean-climate dynamics. By integrating multi-scale observational data with state-of-the-art climate modeling approaches, researchers have enhanced the robustness of climate projections, ensuring that decision-makers have the necessary information to develop science-based policies for mitigating and adapting to climate change.

Numerical Techniques, Modeling, and Forecasting Approaches

Advancements in numerical modeling have been central to improving climate projections, enhancing the representation of oceanic and atmospheric processes across multiple spatial and temporal scales. The development of ensemble-based data assimilation techniques has improved the initialization of climate models, reducing forecast uncertainties and increasing the reliability of long-term climate simulations. By incorporating diverse observational datasets, including satellite data and in situ measurements, these methods have refined predictions of ocean circulation, temperature variability, and extreme weather occurrences (PREVASSEMBLE).

Refinements in turbulence parameterization have addressed persistent challenges in climate modeling, particularly in the representation of ocean mixing processes. Traditional models have struggled to capture the full complexity of small-scale turbulence, which plays a critical role in oceanic heat and carbon transport. Recent efforts have focused on integrating improved turbulence closure schemes into climate models, leading to enhanced accuracy in sea surface temperature predictions and better representation of subsurface ocean dynamics (CONTACTS).

The predictability of the Atlantic Meridional Overturning Circulation (AMOC) has been a key area of investigation, given its pivotal role in regulating global climate. Research has provided new insights into AMOC variability, exploring its sensitivity to anthropogenic forcing and internal climate oscillations. Model simulations have revealed the potential weakening of AMOC under continued warming scenarios, with implications for regional and global climate patterns. These studies have contributed to a more nuanced understanding of how AMOC interacts with atmospheric dynamics and ocean heat transport, improving long-term climate projections (ARCHANGE).

Beyond physical climate modeling, innovative climate risk assessment frameworks have been developed to evaluate the socio-economic impacts of climate change. By integrating climate projections with economic and infrastructural data, researchers have created decision-support tools that aid policymakers in designing effective adaptation and mitigation strategies. These frameworks have been particularly instrumental in assessing risks associated with extreme weather events, sea-level rise, and coastal vulnerability, providing actionable insights for urban planning and infrastructure resilience (RISCCi).

Collectively, these advances in numerical modeling and forecasting have significantly improved our ability to predict climate variability and assess future climate risks. By refining model parameterizations, enhancing data assimilation techniques, and developing interdisciplinary risk assessment tools, researchers have strengthened the scientific foundation for informed policy-making in the face of a changing climate.

Regional Focus on the Arctic and Mediterranean Sea

The Arctic and Mediterranean regions have been identified as climate change hotspots due to their heightened sensitivity to warming trends and environmental changes. In the Mediterranean, research has focused on hydro-climatic variability, ecosystem resilience, and socio-economic adaptation strategies. Studies have examined shifting precipitation patterns, land degradation, and the impact of warming on ocean circulation within this semi-enclosed sea. By integrating climate models with observational data, researchers have improved projections of Mediterranean climate shifts, providing critical insights for water resource management, biodiversity conservation, and urban resilience planning (OTMed).

In the Arctic, accelerating ice loss and shifts in oceanic circulation have prompted extensive investigations into ice-ocean interactions and their broader implications for global climate feedbacks. Observational campaigns have tracked sea ice retreat, permafrost thaw, and freshwater fluxes, offering a detailed assessment of how Arctic changes influence atmospheric and oceanic circulation patterns. These studies have underscored the role of Arctic processes in modulating hemispheric weather patterns and have contributed to improved representations of polar dynamics in Earth system models (ARCHANGE).

High-resolution modeling and field-based research have played a pivotal role in refining climate projections for both regions. By leveraging advanced computational techniques, scientists have been able to simulate complex interactions between oceanic and atmospheric processes, improving long-term climate predictions. These efforts have not only enhanced scientific understanding of regional climate variability but have also informed policy decisions aimed at mitigating the risks associated with climate change in vulnerable coastal and polar environments (TESS).

Continued monitoring and interdisciplinary modeling approaches are essential for advancing climate research in these regions. By integrating physical, biological, and socio-economic perspectives, researchers are improving our capacity to anticipate climate-induced changes and develop adaptive strategies for communities dependent on Mediterranean and Arctic ecosystems. Strengthening international collaborations and expanding observational networks will be crucial for refining climate models and addressing the evolving challenges posed by climate change in these two highly sensitive regions (ISBlue).

Triple point “climate/biogeochemistry/biodiversity”

In the oceans, it is crucial to understand the biogeochemical processes linking physics to biodiversity, and their role for a better conservation and sustainably use of the oceans, seas and marine resources (SDG14) or for a long-term uptake of atmospheric CO₂ excess (SDG13). Here, selected advancements by ANR projects are presented from coastal to remote areas and the global ocean.

Oceans are highly impacted by changing river discharges, bringing continental sediment, carbon, nutrients and pollutants. Heterogeneous processes in space and time were captured with new observing systems from satellite observation of dissolved organic matter (GLOBCOAST¹), to particulate organic matter consumption in shallow sediment using in-situ oxygen sensors off Rhone (CHACCRA²) or at very deep depth using ROVs off Congo (CONGOLOBE³).

In a changing climate with higher temperature and acidification, it was shown a poleward transient of species as phytoplankton calcifier as Emiliana Huxleyi (CALHIS⁴) in competition with silicifier as diatoms (PHYTOMET⁵) to sequester carbon. Sensitivity to micronutrients is also a key process find not limited to iron availability but to interaction with copper (PHYTOMET⁶, ICOP⁷). Furthermore, the production of DMS and DMSP, precursors of aerosols and cloud condensation nuclei, due to combined macro- and micro-nutrient stresses had been simulated for first time at global level (ICOP⁸).

In polar and sub-polar areas, using ships, automatic buoys or elephant seal sensors, advancements highlight the specific interaction between ocean circulation and sea-ice condition, biological pump and nutrient fluxes (EXCITING⁹, SOBUMS¹⁰). Studies cover from Arctic Ocean, where a large diversity of photoheterotrophic bacteria was discovered (RHOMEO¹¹), to Austral Ocean showing how the Kerguelen plateau and subsequent transport by eddies drives iron use and recycling by biology in summertime (EXCITING¹²).

In remote areas as South West Pacific where waters are poor in nutrients, a detailed analysis was made on diazotrophic species (UCYN-A, UCYN-B), that fix atmospheric nitrogen gas and use atmospheric deposition allowing to support significant productivity off Fidji and Caledonia (OUTPACE).

Using state of the art model for global ocean circulation, biogeochemistry and planktons, sensitivity studies to global warming show significant impacts on both biodiversity and capacity of oceans to uptake the excess CO₂, from diurnal amplitude to seasonal cycle and long-term trends (SOBUMS^13,14).

2.2 Innovation for Enterprises, Science Policy, and Citizens

Scientific advancements in ocean-climate research have led to the development of technological innovations with direct applications in industry, policymaking, and societal resilience. The commercialization of advanced environmental monitoring tools has provided industries with new capabilities for assessing oceanic and atmospheric changes, particularly for sectors dependent on marine resources and weather-sensitive operations. These technologies have improved oceanographic data collection, real-time forecasting, and climate-informed decision-making in various economic sectors, including shipping, fisheries, and renewable energy production (SUBGLACIOR).

The enhancement of climate services has played a pivotal role in translating scientific research into actionable insights for policymakers. By integrating observational data and numerical modeling, researchers have developed tailored climate information systems that support adaptation planning at regional and national scales. These services have been instrumental in informing policy frameworks related to coastal protection, water resource management, and disaster preparedness, particularly in vulnerable regions such as the Mediterranean and Arctic (ISBlue).

Advances in climate risk assessment have strengthened infrastructure resilience strategies, particularly for urban areas exposed to rising sea levels and extreme weather events. The integration of climate projections into urban planning processes has facilitated the design of adaptive infrastructure capable of withstanding climate-induced hazards. These efforts have provided city planners and decision-makers with critical information for implementing sustainable adaptation measures, reducing economic and social vulnerabilities to climate change (IPSL-CGS).

Improved forecasting capabilities have enhanced disaster preparedness, enabling more effective responses to extreme weather events. The development of real-time monitoring systems and early warning frameworks has been crucial in mitigating the impacts of hurricanes, storm surges, and heatwaves. These tools have been particularly valuable for emergency response agencies, ensuring that communities are better equipped to handle climate-related risks (RISCCi).

Furthermore, Arctic monitoring initiatives have provided essential data for maritime operations and climate negotiations. Enhanced observational networks in polar regions have improved the understanding of sea ice variability, facilitating safer navigation in Arctic waters and contributing to global climate agreements aimed at mitigating the effects of climate change. The integration of these data into climate models has also refined projections of ice melt and its implications for global sea-level rise (WaveSIMM).

These innovations in environmental monitoring, climate services, and risk assessment have translated scientific advancements into practical applications that benefit industries, policymakers, and society at large. By fostering interdisciplinary collaboration and expanding the reach of climate research, these efforts continue to drive meaningful progress in climate adaptation and resilience planning.

Human habitat and health are impacted by changes in coastal biogeochemistry and biodiversity, affecting water, air or food quality.

Investigation on harmful algae blooms (HAB) of Ostreopsis spp. shows the biotic relationships with their environment, opening ways to monitor and prevent direct impacts on humans (OCEAN-15¹⁵).

On vulnerability of shellfish farmers to HAB events, an optimal matching analysis of closure decrees were made by linking to ecological HAB knowledge (CoCliME¹⁶), opening ways for economic optimization.

Using Thau Lagoon as a global warming experiment, it was demonstrated that exceptional warm year would have a strong impact on composition, succession, and association of microbial communities (Photo-Phyto)

2.3 Links to Human Societies

The integration of ocean-climate research with societal needs has expanded our understanding of how environmental changes impact communities and governance structures. Climate-driven migration has been a growing concern, particularly in deltaic and low-lying coastal regions where rising sea levels and increased storm surges threaten livelihoods. Studies have investigated the interplay between environmental degradation, socio-economic factors, and displacement trends, providing a foundation for policy frameworks that support affected populations. These efforts have facilitated the development of adaptation strategies that incorporate both physical resilience, such as improved flood protection infrastructure, and social resilience, including economic diversification and relocation planning (MOVINDELTAS).

Coastal protection has been a key focus of research, aiming to balance engineering solutions with ecological sustainability. Investigations into the effectiveness of dikes, natural buffers, and hybrid infrastructure approaches have provided new perspectives on how to manage coastal risks in the face of increasing climate extremes. By assessing long-term shoreline evolution and the impact of human interventions, researchers have offered valuable insights into designing adaptive coastal management strategies that maintain both environmental integrity and economic viability (DIGUES).

Historical analyses of environmental changes have played a crucial role in understanding long-term patterns of human adaptation to shifting climatic conditions. Through interdisciplinary research integrating geological, archaeological, and historical records, scientists have reconstructed past coastal settlements, resource use, and disaster response strategies. These studies have highlighted the resilience and vulnerability of past societies, offering lessons applicable to contemporary climate adaptation efforts. Understanding how historical communities navigated climate variability informs present-day decision-making for managing risks associated with rising sea levels and changing weather patterns (ARMILIT).

The inclusion of socio-economic considerations in climate research has fostered interdisciplinary approaches that address sustainability and resilience-building. By engaging with local stakeholders, researchers have facilitated knowledge exchange between scientific communities and policy practitioners, ensuring that adaptation strategies are both effective and culturally appropriate. This approach has been particularly valuable in regions like the Mediterranean, where climate change intersects with complex socio-political and economic challenges. Efforts to integrate environmental justice, resource equity, and participatory governance into climate adaptation have strengthened the ability of local communities to navigate climate risks in an inclusive and sustainable manner (OTMed).

Collectively, these advances in understanding the links between ocean-climate dynamics and human societies have provided a scientific basis for informed policy and community-based adaptation strategies. By incorporating historical, economic, and governance perspectives, research efforts continue to bridge the gap between scientific knowledge and practical applications for addressing climate challenges in vulnerable regions.

2.4 Methodological Breakthroughs

Innovative methodologies have played a crucial role in advancing ocean-climate research, enhancing our ability to reconstruct past climates, predict future changes, and refine climate models. High-resolution paleoclimate reconstructions have enabled scientists to capture finer details of past environmental variability, improving our understanding of the drivers of long-term climate change. By integrating high-precision ice-core drilling techniques and novel geochemical analysis methods, researchers have been able to extract more accurate climate signals from natural archives, offering refined insights into past temperature fluctuations and atmospheric composition changes (CLIMCOR).

The evolution of ensemble forecasting techniques has significantly improved predictive capabilities, allowing for better representation of uncertainty in climate projections. By using multiple model runs with varied initial conditions, scientists have enhanced the reliability of long-term forecasts, particularly for complex climate processes such as ocean circulation patterns and atmospheric teleconnections. This methodological advancement has strengthened climate risk assessments and informed decision-making for adaptation strategies in climate-sensitive regions (PREVASSEMBLE).

The refinement of data assimilation methods has led to substantial improvements in climate model accuracy, bridging the gap between observational data and numerical simulations. Advanced assimilation algorithms now integrate real-time observations from satellites, oceanographic buoys, and atmospheric monitoring systems into models, reducing errors in long-term climate projections. These improvements have been instrumental in refining estimates of ocean heat uptake, sea-level rise projections, and extreme weather event predictions, contributing to better-informed climate policies (IODA-MED).

New observational technologies have expanded our ability to monitor ocean-atmosphere interactions in greater detail, providing critical data for refining climate models and informing policy decisions. Advances in underwater and atmospheric sensing have facilitated continuous real-time monitoring of key climate variables such as oceanic CO₂ uptake, sea surface temperature variability, and atmospheric water vapor content. The integration of these novel observation techniques into climate research has not only improved climate model calibration but has also strengthened early warning systems for climate-related disasters (SUBGLACIOR).

Additionally, improvements in high-resolution modeling of tropical cyclone dynamics have enhanced our understanding of how extreme weather events interact with oceanic processes. Refined numerical simulations of cyclone-ocean interactions have provided new insights into how storms contribute to ocean heat distribution and how they may intensify in a warming climate. These methodological advancements have led to more accurate projections of cyclone intensity and trajectory, which are crucial for disaster preparedness and risk mitigation efforts in vulnerable coastal areas (TROCODYN).

Together, these methodological breakthroughs have strengthened the scientific foundation of ocean-climate research, enabling more precise reconstructions of past climate, improved climate predictions, and enhanced observational capabilities. By integrating high-resolution observations, advanced modeling techniques, and innovative forecasting approaches, researchers continue to refine our understanding of ocean-climate interactions and provide valuable insights for climate adaptation and mitigation efforts.

Methodological breakthrough in “climate/biogeochemistry/biodiversity” includes :

Method for analysing sedimentary samples with automatic recognition of nanofossils (patent WO/2015/132531)
PRO2FLUX – A software program for profile quantification and diffusive O2 flux calculations (http://dx.doi.org/10.1016/j.envsoft.2009.10.015)
Efficient, fast and inexpensive bioassay to monitor benthic microalgae toxicity: Application to Ostreopsis species (http://dx.doi.org/10.1016/j.aquatox.2020.105485)

3 Research Perspectives

3.1 Scientific Barriers and Gaps

Major challenges remain to estimate the reduced capacity of the oceans to uptake excess CO₂ under an on-going global warming overshoot, i.e. beyond 1.5-2°C (PRATO¹⁷). Despite the reasonable simulation of surface ocean pCO₂ by the global ocean biogeochemical models (GOBMs), there are still strong discrepancies at regional and seasonal level. Main uncertainties are related to the weak constrain of the Southern Ocean by observations (SOBUMS18), as well as in coastal areas impacted by direct sea use and by changing input from rivers (COCAS).

Better representation of marine biodiversity driven by micro-nutrients (ICOP¹⁹, ISBLEU and LABEX-MER^20,21) into models should benefit on trait-based functional diversity (EFFICACY²²) as well as from advanced satellite using sea surface hue. Significant progress is needed also on changing ecosystem habitat, since coastal areas impacted directly by anthropogenic activities (e.g. Posidonia in Mediterranean Sea, OTMED²³) to open ocean where a poleward shift happens due to global warming (TULIP²⁴).

Finally, as for climate physics, it is expected significant progress on coupling physics, biogeochemistry and biodiversity with massive data assimilation using artificial intelligence (MEDIATION) at fine space and time resolution (BIOSWOT), if learning datasets are qualified and results evaluated.

Despite considerable advances in ocean-climate research, significant challenges persist, limiting our ability to fully characterize the ocean’s role in the climate system and predict its future evolution. One of the most pressing issues concerns the representation of fine-scale ocean dynamics, particularly sub-mesoscale turbulence and internal wave-driven mixing, which govern critical processes such as heat transport, stratification, and carbon sequestration. These small-scale features, though ubiquitous in the ocean, are often unresolved or poorly parameterized in climate models due to computational constraints. Their influence on large-scale circulation, air-sea exchanges, and biogeochemical fluxes remains an area of active investigation. The integration of high-resolution numerical modeling with novel parameterization schemes is imperative to bridge this gap and improve projections of ocean-atmosphere interactions.

Extreme weather events, particularly tropical cyclones and marine heatwaves, underscore another crucial area of uncertainty. The exchange of heat and moisture between the ocean and atmosphere is fundamental to storm intensification and precipitation extremes, yet the complexity of these interactions remains difficult to quantify. The role of ocean heat content in modulating cyclone intensity, the feedbacks between upper-ocean mixing and storm dynamics, and the compounding effects of marine heatwaves on atmospheric circulation all require deeper exploration. The limited temporal and spatial resolution of current observational networks, particularly in high-impact regions, further hinders progress in this domain.

Anthropogenic forcing is also driving fundamental shifts in ocean biogeochemistry, yet the full extent of these changes and their feedbacks on climate remain poorly constrained. The ocean's capacity to act as a carbon sink is being altered by rising temperatures, changes in overturning circulation, and biological responses to acidification and deoxygenation. While global trends indicate a continued uptake of anthropogenic CO₂ by the ocean, regional variations and long-term buffering capacity remain uncertain. The interplay between physical and biological carbon sequestration mechanisms, particularly in high-latitude and deep-ocean environments, needs to be more thoroughly investigated. Additionally, expanding oxygen minimum zones and disruptions to nutrient cycling threaten the stability of marine ecosystems, with cascading effects on productivity and food security.

Bridging the temporal divide between past climate reconstructions and future projections remains another fundamental challenge. Paleoclimate records provide invaluable insights into natural climate variability, past warm periods, and abrupt shifts in ocean circulation. However, the translation of these records into predictive frameworks is constrained by uncertainties in proxy reconstructions, spatial coverage limitations, and disparities between past and present boundary conditions. Further methodological advancements are needed to improve the integration of paleo-data into Earth system models, thereby refining our understanding of climate sensitivity and potential tipping points.

3.2 Innovation Needs

Addressing these challenges requires a paradigm shift in ocean-climate research, driven by interdisciplinary integration, technological innovation, and enhanced international collaboration. A central priority is the development of coupled observational and modeling frameworks that merge satellite remote sensing, in situ measurements, and high-resolution simulations. While satellite missions provide global coverage of sea surface temperature, salinity, and ocean color, their limited depth penetration necessitates complementary in situ observations, particularly for understanding processes occurring beneath the ocean surface and at the air-sea interface.

Innovation in in-situ ocean observations is particularly critical for improving the representation of fine-scale dynamics and ocean-atmosphere coupling in climate models. The deployment of next-generation autonomous observing platforms capable of operating in extreme and remote environments will revolutionize ocean monitoring. The expansion of Biogeochemical-Argo (BGC-Argo) floats provides an unprecedented opportunity to track oceanic carbon uptake, oxygen dynamics, and nutrient cycling in near-real time. Extending these networks to abyssal depths through deep Argo floats and enhancing under-ice observations with autonomous gliders will improve our understanding of deep-ocean processes and ice-ocean interactions, key drivers of sea level rise and heat redistribution.

At the air-sea interface, the development of uncrewed surface vehicles (USVs) is transforming our ability to capture high-resolution fluxes of heat, momentum, and gas exchange. These platforms allow for continuous measurements over large spatial scales and provide critical insights into processes driving ocean-atmosphere feedbacks, particularly during extreme weather events such as hurricanes and atmospheric rivers. In tandem, drifting buoys and moored observatories equipped with advanced turbulence sensors and eddy-covariance flux instruments are enabling direct measurements of near-surface mixing, wave-driven momentum transfer, and aerosol interactions, all of which are essential for refining climate model parameterizations. Complementing these efforts, high-altitude drones and hyperspectral UAVs can be deployed to capture detailed observations of wave breaking, sea spray dynamics, and atmospheric boundary layer evolution.

Further innovation is needed in sensor development to enhance the precision, sensitivity, and longevity of oceanographic measurements, particularly in extreme environments. Miniaturized, low-power sensors capable of measuring biogeochemical variables such as pH, dissolved oxygen, and carbon fluxes at high spatial and temporal resolution will be essential for improving our understanding of ocean feedback mechanisms. Advances in microsensor technologies, bio-optical sensors, and passive acoustic monitoring will enable new insights into biological productivity, ocean mixing, and marine ecosystem responses to climate change. Furthermore, the integration of self-calibrating and energy-efficient sensor networks will enhance long-term ocean monitoring by reducing maintenance costs and improving data quality over extended deployment periods.

The development of low-cost, scalable observing platforms will also be critical for expanding global ocean monitoring capacity, particularly in under-sampled regions such as the Southern Ocean and the deep tropics. Novel designs for cost-effective drifters, expendable probes, and lightweight autonomous vehicles can facilitate the deployment of large-scale sensor networks while maintaining affordability and accessibility for research institutions in developing nations. Open-source hardware and collaborative engineering approaches will further accelerate innovation in low-cost ocean observation technologies, making high-resolution climate data more widely available for scientific and policy applications.

Beyond fundamental research, strengthening the interface between scientific advancements and applied climate services is imperative. More accurate and regionally tailored climate risk assessments will be essential for informing coastal adaptation, disaster mitigation, and policy decision-making. The development of early warning systems for extreme oceanic and atmospheric events—leveraging advancements in artificial intelligence and real-time data assimilation—can provide critical lead time for vulnerable communities. Particular emphasis should be placed on enhancing predictive capacity for compound events, where multiple climate hazards, such as marine heatwaves and intensified storms, interact to amplify risks.
Innovation in climate modeling remains another key area for progress. Future efforts must focus on improving the representation of small-scale processes in global Earth system models while maintaining computational efficiency. This includes advancements in eddy-resolving simulations, stochastic parameterization approaches, and the development of digital twin ocean models that integrate real-time observational data with high-fidelity numerical simulations. Such approaches will enable more accurate projections of sea level rise, ocean circulation shifts, and biogeochemical feedbacks, ultimately reducing uncertainty in long-term climate scenarios.

A global and coordinated research effort is essential to achieve these objectives. Strengthening international scientific collaborations, enhancing data-sharing frameworks, and investing in capacity-building initiatives for developing nations will be crucial for advancing ocean-climate science. The establishment of interdisciplinary research consortia and the expansion of global observational programs, such as the Global Ocean Observing System (GOOS), will provide the necessary foundation for addressing the evolving challenges posed by climate change.

By leveraging technological advancements, integrating diverse scientific disciplines, and fostering global cooperation, ocean-climate research can move toward a more comprehensive and predictive understanding of the Earth system. These efforts will not only enhance our ability to anticipate future climate trajectories but also support the development of informed and sustainable strategies for mitigating and adapting to the profound transformations unfolding in the global ocean.

¹ CDOM-DOC relationship in contrasted coastal waters: implication for DOC retrieval from ocean color remote sensing observation. http://dx.doi.org/10.1364/oe.23.000033
² Temporal variability of carbon recycling in coastal sediments influenced by rivers: assessing the impact of flood inputs in the Rhône River prodelta. http://dx.doi.org/10.5194/bg-7-1187-2010
³ The Congolobe project, a multidisciplinary study of Congo deep-sea fan lobe complex: Overview of methods, strategies, observations and sampling. https://doi.org/10.1016/j.dsr2.2016.05.006
⁴ Poleward expansion of the coccolithophore Emiliania huxleyi. http://dx.doi.org/10.1093/plankt/fbt110
⁵ Carbon Dioxide Concentration Mechanisms in Natural Populations of Marine Diatoms: Insights From Tara Oceans. http://dx.doi.org/10.3389/fpls.2021.657821
⁶ Copper and iron metabolism in Ostreococcus tauri – the role of phytotransferrin, plastocyanin and a chloroplast copper-transporting ATPase. http://dx.doi.org/10.1039/c9mt00078j
⁷ Physiological adaptation of the diatom Pseudo-nitzschia delicatissima under copper starvation. http://dx.doi.org/10.1016/j.marenvres.2023.105995
⁸ Effects of light and phosphorus on summer DMS dynamics in subtropical waters using a global ocean biogeochemical model. http://dx.doi.org/10.1071/en14265
⁹ Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing. http://dx.doi.org/10.1038/ngeo2101
¹⁰ The role of submesoscale currents in structuring marine ecosystems. http://dx.doi.org/10.1038/s41467-018-07059-3
¹¹ Diversity of Arctic Pelagic Bacteria with an emphasis on photoheterotrophs: a review. http://dx.doi.org/10.5194/bg-11-3309-2014
¹² Iron budgets for three distinct biogeochemical sites around the Kerguelen Archipelago (Southern Ocean) during the natural fertilisation study, KEOPS-2. http://dx.doi.org/10.5194/bg-12-4421-2015
¹³ Modified future diurnal variability of the global surface ocean CO₂ system. http://dx.doi.org/10.1111/gcb.16514
¹⁴ Arctic Ocean annual high in pCO₂ could shift from winter to summer. http://dx.doi.org/10.1038/s41586-022-05205-y
¹⁵ Chemical Ecology of the Benthic Dinoflagellate Genus Ostreopsis: Review of Progress and Future Directions. http://dx.doi.org/10.3389/fmars.2020.00498
¹⁶ The vulnerability of shellfish farmers to HAB events: An optimal matching analysis of closure decrees. http://dx.doi.org/10.1016/j.hal.2020.101968
¹⁷ Carbon Cycle Response to Temperature Overshoot Beyond 2°C: An Analysis of CMIP6 Models. http://dx.doi.org/10.1029/2020ef001967
¹⁸ Consistency and Challenges in the Ocean Carbon Sink Estimate for the Global Carbon Budget. http://dx.doi.org/10.3389/fmars.2020.571720
¹⁹ Iron and copper limitations differently affect growth rates and photosynthetic and physiological parameters of the marine diatom Pseudo‐nitzschia delicatissima. http://dx.doi.org/10.4319/lo.2013.58.2.0613
²⁰ New insights into the distributions of nitrogen fixation and diazotrophs revealed by high-resolution sensing and sampling methods. http://dx.doi.org/10.1038/s41396-020-0703-6
²¹ Thermal stress reduces pocilloporid coral resilience to ocean acidification by impairing control over calcifying fluid chemistry. http://dx.doi.org/10.1126/sciadv.aba9958
²² Differential global distribution of marine picocyanobacteria gene clusters reveals distinct niche-related adaptive strategies. http://dx.doi.org/10.1038/s41396-023-01386-0
²³ Biogeomorphology of the Mediterranean Posidonia oceanica seagrass meadows. http://dx.doi.org/10.1002/esp.3932
²⁴ Species better track climate warming in the oceans than on land. http://dx.doi.org/10.1038/s41559-020-1198-2

Hydrodynamic researches

In the context of ocean dynamics, significant progress has been made thanks to technical advances, particularly high-resolution numerical modeling, and multidisciplinary approaches. 118 ANR projects have led to major advances in understanding hydrodynamics, particularly regarding thermohaline circulation, turbulence, and multi-scale interactions. Key results include improving climate and weather models through high-resolution simulations and the use of gliders to collect small-scale data. The projects have also highlighted the variability of the North Atlantic and its role in regulating the global climate. Perspectives open up on the integration of multi-source data in real-time with AI-based modeling, as well as an interdisciplinary approach to improve environmental forecasts and climate resilience strategies.

Laurent Mortier : ENSTA Paris

1) Scientific background:

Over the past two decades, significant progress has been made in understanding oceanic and atmospheric dynamics, with a particular focus on hydrodynamics at different scales and in various geophysical contexts. International research has also increasingly focused on the coupling between physical, chemical and biological processes in ocean systems, particularly in the coastal zone or in regions affected by extreme events. This evolution towards multidisciplinary approaches, where for example geochemistry, sediment transport and tectonic interactions are addressed in a holistic manner, also allows for a better assessment of environmental risks.

A central development in this field has been the development and application of non-equilibrium statistical mechanics methods, and of course high-resolution numerical modelling supported by advanced mathematical methods to describe complex fluid systems. These methods go beyond traditional deterministic approaches by integrating probabilistic frameworks considering the internal variability and stochastic forcing in the ocean-atmosphere system. In general, theoretical results are extended thanks to modern computational tools and more realistic forcing scenarios, thus providing a solid scientific basis for societal applications.

At the same time, autonomous systems have become increasingly common in oceanographic measurement and data collection, making it possible to obtain real-time, high-resolution information on dynamic environments and at scales that could not be addressed by conventional methods. This technological leap complements theoretical and numerical progress, enabling a fruitful data-model approach, leading to a more integrated understanding of ocean circulation, wave propagation and climate dynamics. All this progress is underpinned by the recognition of the central role of the ocean in the Earth's climate system, which is stimulating a sustained international effort to refine models, improve observation capacity and link hydrodynamics research to broader environmental and societal challenges.

2) Main Contributions of the French Communities through ANR (co)funding

2-1: Scientific progress and cutting-edge advances

Of all the projects funded by the ANR in the field of hydrodynamics, a significant body of scientific knowledge has been generated, focusing on coastal hydrodynamics, the interactions between the ocean, the atmosphere and the climate, but also in relation to biogeochemistry and geosciences, with implications for scientific progress and societal benefit.

These projects have led to major advances in our understanding of oceanic and atmospheric dynamics at several scales, from thermohaline circulation to turbulence at the submeso scale. This work has led us to rethink our approach to certain processes in complex geophysical systems, with a particular emphasis on multi-scale interactions, the coupling of processes and transdisciplinary observation strategies.

Many of these projects have explored in detail the dynamics of turbulent and non-linear fluids in oceanic and atmospheric systems. The STATFLOW project, for example, has pushed back the limits of turbulence theory by applying statistical mechanics to characterise the stability of equilibriums and abrupt transitions in rotating and stratified flows. These findings enhance our understanding of ocean-atmosphere interactions and directly inform improvements in climate and weather models. The S.T.I. project also illustrates the general progress in the field of computational hydrodynamics thanks to high-resolution numerical simulations, or using Large Eddy Simulations (LES) approaches and parallel computing architectures to study the behaviour of nonlinear wave phenomena and the formation of eddies with unprecedented fidelity.

In terms of observational breakthroughs, the LIVINGSTONE project illustrates innovation in autonomous exploration. By deploying gliders capable of adaptive sampling, the researchers captured small-scale physical variability over large time windows, offering new perspectives on the observation of diapycnal mixing, internal wave dynamics and (sub)mesoscale phenomena. These data, rarely accessible through conventional oceanographic campaigns, support the development of reconstructions of the state of the oceans using new-generation observation methods.

Projects such as NEWTON have contributed significantly to our understanding of large-scale circulation patterns, particularly the variability of the North Atlantic and its role in regulating the global climate. By integrating hydrographic data, particularly chemical tracers, Argo floats and satellite altimetry, NEWTON and similar projects work has confirmed displacement patterns in deep convection zones and interior oceanic transport pathways, with implications for heat redistribution and carbon absorption on a planetary scale.

Another frontier explored by several projects is the coupling of continental and marine hydrosystems. The AMANDES project focused on sediment flux and associated geochemical processes off the Amazon estuary, illustrating the importance of the coastal zone in biogeochemical cycles in the ocean. These discoveries challenge the traditional segmentation of the Earth and marine sciences and emphasise again the need for integrated modelling of the land-ocean continuum.

Several projects have also contributed substantially to the improvement of forecasting capabilities through ensemble modelling, data assimilation and real-time simulation. Additionally, PRECOC has demonstrated that the quality of forecasts from operational coastal models can be assessed in real time using independent data. This is especially important for managing coastal water quality, for example.

Collectively, these scientific advances represent a qualitative leap in geophysical fluid dynamics, in the joint strategies of modelling and use of observations. They are pushing back the frontiers of knowledge not only in the field of coastal hydrodynamics, but also in that of deep ocean processes, atmospheric physics and coupled terrestrial systems, thus laying the foundations for a better understanding of natural variability and for anticipating future environmental states. These advances will make operational applications, such as those for managing the marine environment, more reliable.

2-2: Innovation at the service of stakeholders

This scientific knowledge has been translated into some usable innovations for the benefit of private companies, political decision-makers and coastal communities.

For private enterprises, advances in high-resolution modelling, real-time data assimilation, and ocean monitoring technologies enhance the range and quality of applications for the marine activities in the coastal zone. Science policy gains from improved predictive tools and integrated frameworks that support climate adaptation, hazard response, and marine spatial planning. For citizens, these innovations translate into more accurate early warning systems, better-informed infrastructure planning, and enhanced environmental stewardship. They will also empower local actors through open data platforms and participatory tools, making complex scientific insights more accessible and actionable.

Together, these innovations highlight the societal value of hydrodynamic research by providing scalable, interdisciplinary solutions to real-world challenges.

2-3: Links and contributions to human societies

The economic and cultural implications of these progresses are particularly relevant in coastal areas where communities are highly dependent on marine resources. Several projects have focused on coastal adaptation, for example by exploring methods for reconstructing past and current changes in sea level, a key factor in planning for future scenarios.

These projects also support the evolution of coastal practices: for example, better modelling of wave-current interactions can enable safer and more efficient maritime traffic and aquaculture practices. On a cultural level, reconstruction studies on storms or sedimentary deposits can shed light on the preservation of local heritage and the regional narration of environmental memory.

2-4: Methodological breakthroughs

Many of these projects represent not only scientific advances, but also methodological innovations. A key trend is the fusion of various observation techniques (satellites, in situ and autonomous platforms) with machine learning and advanced statistical modelling. This hybrid approach has set a new standard in geoscientific methodology, improving the reliability and resolution of hydrodynamics models.

Another advance lies in the use of multi-scale modelling frameworks with massive parallel computing. This makes it possible to realistically simulate physical processes at different scales, from basin-wide currents to localised sediment transport, making it possible to address both global and local issues within the same modelling ecosystem.

3) Research perspectives coming out of the ANR (co)funded projects

The overall results of the projects in the hydrodynamics field indicate a transformative evolution in the study of oceanic and atmospheric dynamics and the related tools for operational applications.

One of the most promising directions for the future is the integration of multi-source data in real time with AI-based modelling frameworks. With the increasing availability of autonomous platforms, satellite observations and high-resolution simulations, the foundations are being laid for dynamic and adaptive ocean components in earth system models capable of responding to rapidly changing climatic, geophysical and anthropogenic conditions.

These projects also highlight a growing need to bridge the gaps between disciplines and spatial scales: from submesoscale turbulence to planetary circulation, from continental hydrology to ocean chemistry. Future efforts will benefit from the continued development of cross-domain coupling frameworks, particularly with regard to biogeochemical fluxes, sediment dynamics and energy transfer processes.

Beyond pure science, the strong commitment to environmental forecasting, risk assessment and monitoring suggests a closer interface with public policy and societal resilience planning. Hydrodynamics research will increasingly serve as a cornerstone for climate adaptation, early risk warning and the sustainable use of the oceans. The tools and methodologies that emerge from these projects, in particular ensemble modelling, data assimilation and hybrid observation systems, are set to become essential infrastructures for managing a changing world.

Polar ecosystems

Polar regions, at the forefront of climate change, are the subject of interdisciplinary research on ice dynamics, marine ecosystems, the role of the Southern Ocean in carbon storage, and the adaptation of Arctic populations. 78 ANR projects have improved knowledge of ice sheet melting, oceanic fluxes, polar biodiversity, and the impacts of pollution. They strengthen the capabilities of future climate modeling. The perspectives emphasize refining sea-level rise projections, integrating past data from ice archives, and the growing importance of social sciences to support transitions in these strategic regions.

Scientific background

The Arctic and Antarctic play a key role in global climate balance and are now at the heart of intensive scientific research. The Arctic is warming about four times faster than the global average, causing rapid sea ice melt, permafrost methane release and disruptions in oceanic and atmospheric circulation. The stability of the Antarctic ice sheet is a decisive factor for future sea level rise. Moreover, the Southern Ocean plays a central role in heat and carbon storage, thereby influencing global climate regulation. The ice sheet’s stability is crucial for future sea level rises. French researchers are involved in physical, biological and social sciences, studying ice melt, carbon fluxes, marine ecosystems, biodiversity and indigenous Arctic communities.

Impacts on public policies and socio-economical innovation

International cooperation is essential, framed by agreements such as the Antarctic Treaty and the efforts of the Arctic Council. This collaboration is supported by technological advances (satellites, autonomous sensors, artificial intelligence), which offer unprecedented precision in observing these remote regions. Polar regions are also of geopolitical interest, with new shipping routes, natural resources, and environmental governance at stake.

Main outcomes of the ANR-funded projects

Projects funded by the the ANR in polar regions have advanced our understanding of glacial, oceanic, ecological and human dynamics under climate change. Glaciological research has highlighted destabilisation processes of polar ice sheets, especially the collapse mechanisms of ice streams and shelves, reconstructed from the last North American deglaciation. These find- ings, integrated into numerical models, refine projections of ice dynamics and sea level rise. High-resolution satellite data have enabled reconstructions of major glaciers in Greenland and Antarctica, improving estimates of ice mass loss, understanding of projection uncertainties and glaciological model assimilation. In Antarctica, Adelie Land is monitored through an integrated approach combining seismology, oceanography, and bioacoustics. Oceanographic studies in the Southern Ocean focused on nutrient and trace element fluxes across water masses. An interdisciplinary approach has clarified interactions between dissolved and suspended particles, crucial for modelling biogeochemical cycles. Arctic ecosystems are also central. Studies have assessed the combined effects of ice melt, mercury pollution and warming on seabirds’ thermoregulation and behaviour. Others explored microalgae adaptation to low winter light, revealing novel growth mechanisms impacting spring blooms. Genomic studies identified genes involved in extreme adaptation. Finally, projects bridging environmental and social sciences have examined the cultural and historical dimensions of Arctic climate change, focusing on local adaptation strategies and perceptions of environmental disruption.

Conclusion and research perspectives

Polar science stands at the frontier of climate research, combining advanced modelling, fieldwork and societal engagement. New research directions are emerging to better understand interactions between ice sheets, polar oceans and climate. A key goal is to improve sea-level rise projections, still marked by high uncertainty due to complex ice sheet dynamics. This involves enhanced modelling of ice-ocean-atmosphere interactions and integrating polar-specific processes often underrepresented in global climate models. Advances in AI also offer tools to improve spatial and temporal model resolution. Reconstructing past ice sheet behaviour since the last glacial maximum supports the validation and refinement of future projections up to 2300. Moreover, deep ice core drilling aims to reach 1.5-million-year-old layers, enabling the study of Earth’s longterm climate evolution during major orbital shifts. Investigating polar ocean biogeochemical cycles – particularly involving trace metals critical for marine productivity – is needed to improve understanding of the ocean’s biological carbon pump and will contribute to building more accurate global models of physical and ecological processes. Specific attention has to support researches on consequences for autochthon populations of biodiversity changes in relation to global warming.

Biogeochemical cycles

Oceanic biogeochemical cycles are at the heart of research on climate regulation, particularly via the biological carbon pump, which allows phytoplankton to trap CO2 at depth. However, projections show that climate change could weaken this mechanism by reducing marine biomass. 59 ANR projects have led to scientific advances concerning the role of the iron cycle, microorganisms, and vertical fluxes. Major technological advances have also been made in areas such as fine modeling, hyperspectral remote sensing, and the use of AI for plankton image analysis, improving climate modeling in connection with public and international policies. The mesopelagic zone (between 200 and 1000 meters deep) remains a priority for understanding the sustainable sequestration of carbon. This research is essential for developing climate mitigation levers and ensuring sustainable ocean management in the 21st century.

N. Savoye : Univ. Bordeaux, UMR EPOC

1- Scientific background:

The study of the cycles of main biogenic elements (C, N, P, Si) in the global ocean took off in the second half of the 20th century. Many studies have focused on the link between these elements and biological production (especially primary production), quantifying the associated fluxes and then establishing global budgets. Global stoichiometric ratios were established as early as the 1960s, and were re-estimated and completed in the 1980s and since. The second half of the 20th century also saw major developments in palaeoceanography, with studies focusing in particular on the link, at very large timescales, between primary production, atmospheric CO₂ and climate. Numerous geochemical proxies have been developed. In this context, the role of iron in limiting phytoplankton primary production has been questioned and tested in vitro and then during large-scale oceanographic campaigns, with the iron fertilisation of nutrient-rich but iron-poor zones where phytoplankton production is limited (HNLC (high nutrients - low chlorophyll) aeras). The hypothesis was that the addition of iron increases phytoplankton production, which consumes atmospheric CO₂ and exports it to the deep ocean, thereby reducing the greenhouse effect and cooling the planet. These processes would explain the link between iron and atmospheric CO₂ during the alternating glacial and inter-glacial periods of the Quaternary era. The vertical fluxes of carbon and the attenuation of these fluxes with depth have been studied in particular and the concept of the biological carbon pump developed: this two-step process involves 1) CO₂ uptake and conversion into particulate organic carbon by phytoplankton and 2) the export of part of this carbon to the deep ocean and its burying in the sediment. From the 1990s onwards, there was growing evidence that human activities, particularly the release of CO₂ into the atmosphere, were leading to global warming. It is in this context that a number of studies have focused on the ocean capacity to sequester carbon via the biological pump and mitigate climate change. The approaches have been both numerical (global modelling) and field-based. These studies initially focused on productive and HNLC areas, oligotrophic areas (nutrient-poor oceanic deserts) being generally considered as having a minor role at global scale. One focal point of a large number of international studies has been to understand the processes leading to the attenuation of vertical carbon fluxes, in relation to the abiotic and biotic environment. The role of microorganisms has obviously been studied, but it was only later that the role of their diversity was taken into account. It was also from the 1990s that carbon budgets were refined by taking into account the diversity of major biogeochemical regions, including the different zones of the coastal ocean.

Over the past two decades, international research has made great leaps forward in the field of oceanic biogeochemical cycles. Regarding the ocean capacity to sequester carbon, the role of iron and its co-limitation with other nutrients and micronutrients to phytoplankton production and also to organic matter remineralization by bacteria have been widely studied, both at the cellular level (in vitro experiments) and at large scale in the field (experiments involving artificial or natural Fe-fertilization of areas of the ocean); the mesopelagic zone (approximately between 100m and 1000m depth) has been particularly scrutinized because it is in this zone that approximately 90% of the attenuation of vertical carbon fluxes occurs. The role of microbial (viruses, bacteria, phytoplankton) and zooplankton biodiversity in biogeochemical flows has been increasingly taken into account, whether in terms of taxonomic, genetic or functional diversity. Local, regional and global models have been significantly refined, notably thanks to better spatio-temporal resolutions, the interweaving of physical scales, the coupling between physical and biogeochemical models, the consideration of a greater diversity of biological compartments and processes thanks to the existence of a greater number of observational and experimental data, data assimilation, sensitivity studies, the consideration of uncertainties, etc. The coastal ocean and its different zones have been better taken into account in global carbon budgets and modelling than previously. In this ocean, characterized by the shallow depth of the water column and the proximity to the continent, studies have focused heavily on the interfaces (continent-ocean, water-sediment, water-air interfaces) and the links with biology (ecology and ecosystem functioning) including biodiversity. In addition, the impact of global change to the biogeochemical functioning of ecosystems has been studied, particularly on a (multi-)decadal scale. A large number of geochemical proxies have been developed, particularly to reconstruct the biogeochemical past of the ocean.

These major recent scientific advances have been made possible thanks to numerous technological and technical advances. This concerns digital technology (very significant increase in data storage capacity and reduction in calculation times), in situ measurements (development of sensors for a growing number of biogeochemical parameters; miniaturization of sensors; wide diversification of vectors capable of carrying these sensors) and remote sensing (improvement of spatial and spectral resolution; diversification of vectors) and their repetition at fixed points (multi-decadal observations), biodiversity (remarkable development of ‘omics’, molecular-biology tools).

The French community has contributed significantly to these scientific advances.

2- Main Contributions of the French Communities through ANR (co)funding (Action plan and France 2030)

2-1 Scientific progress; cutting edge science

- Ocean capacity to sequester carbon

Through ANR funding, the French community has made a major contribution to understanding and quantifying the ocean capacity to sequester carbon. It has focused on surface processes (production/remineralisation/export) and mesopelagic and deep-sea processes (export/remineralisation/sequestration). It has endeavoured to understand and integrate very fine scales and processes (cellular and particle scale) as well as very large scales (global ocean). French teams have been particularly involved in the study of the biogeochemical cycle of iron coupled with that of carbon, whether on a cellular or ecosystem scale, vertical carbon flows and the role of diazotrophs (micro-organisms capable of using atmospheric nitrogen dissolved in seawater as a source of nitrogenous nutrient in oceanic deserts), various silicified and calcified planktonic groups and bacteria in the study of the production, remineralisation and export of carbon from the surface ocean to the deep ocean (carbon biological pump) and therefore of the ocean capacity to sequester carbon. More broadly, these studies have contributed significantly to a better understanding of the global carbon cycle and associated biogenic elements (N, Si, Fe, etc.).

In situ mesocosms experiments have shown that in oceanic deserts (oligotrophic zones that are poor in nutrients and therefore in marine life), diazotrophs support a significant proportion of biological production and contribute, in these zones, to a much greater export of carbon than when they are absent. This work was reinforced by the monitoring of water body in the south-western tropical Pacific, which showed that atmospheric nitrogen fixation accounted for 90% of the new nitrogen supply and contributed up to 15% of the primary production in a zone where the export efficiency could be as high as 10%, and that diazotrophs accounted for 30% of the carbon exported. This nitrogen input through diazotrophy is also transferred to non-diazotrophic phytoplankton and zooplankton organisms, which in turn contribute to carbon export. Thus, directly or indirectly, more than 50% of exported production was supported by atmospheric nitrogen fixation. All these flows are controlled by the availability of nutrients (mainly phosphorus and iron).

Iron is an essential element for the growth of phytoplankton and other microbial organisms, as it is involved in numerous cellular processes. Its concentration limits the primary production in many areas of the global ocean, so iron is very often taken into account in research dedicated to the carbon biological pump of the ocean. At the cellular level, the mechanisms of incorporation of different forms of iron and their metabolism by marine phytoplankton have been studied, considering the different responses of taxonomic groups to iron limitation and seasonal variability. The limitations and co-limitations of iron and copper on the production and remineralisation of diatoms were also studied at the scale of species and of communities by combining experimental measurements, in situ measurements and modelling. The results show that responses vary from one region of the ocean to another one.

Numerous studies have looked at the different sources of iron (sedimentary, wind, hydrothermal inputs, etc.) and the impact of their input to the carbon biological pump. In the oligotrophic tropical Pacific Ocean, the addition of iron to the euphotic zone by shallow submarine volcanoes helps to structure the phytoplankton community, activating the primary production of diazotrophs and the export of carbon both directly (sedimentation of phytoplankton cells) and indirectly (after grazing by zooplankton). In the oligotrophic Mediterranean Sea, the chemical, biological and particle-dynamic changes caused by a Saharan event (windblown sand) were studied using in situ mesocosms. The results show that the cycles of components of biogeochemical interest (nutrients, metals) are modified by atmospheric inputs: the new nutrients induced are consumed very quickly; there is competition for the new nutrient resource, with heterotrophic bacteria being favoured; diazotrophic organisms, although responsible for only a small percentage of the new carbon production induced, are stimulated by the atmospheric input; the export of particulate carbon is partly linked to processes of organic matter aggregation with mineral particles (ballast effect). Thus, atmospheric inputs not only induce fertilisation for organisms in the surface ocean but also, via aggregation processes, export organic carbon to the deep ocean.

The study of the natural iron fertilisation of the Kerguelen Plateau and adjacent waters in the Southern Ocean has enabled researchers to identify the fertilisation mechanisms and to show that fertilisation increases primary production and its export beyond the surface ocean, but that export efficiency (the proportion of production that is exported) and transfer to the deep ocean depend on the extent of fertilisation and on the phytoplankton communities present.

They vary according to chemical elements (carbon, silicon, nitrogen, iron), from complete remineralisation in the water column to accumulation in the sediments and therefore an effective biological pump. The carbon flux linked to the migration of zooplankton has also been quantified.

With specific regard to diatoms, which contribute most to the carbon biological pump at global scale, it has been shown in the Arctic Ocean that their aggregation, which appears as soon as dissolved silicon becomes limiting, promotes export by both sedimentation and active transport, since copepods follow the aggregates during their sinking. The role of rhizarians, a biomineralizing unicellular zooplankton group capable of mixotrophy and detrivory, in the carbon and silicon biogeochemical cycles has been studied, and the size of their biomass and their contribution to carbon fluxes have been quantified at global scale.

The use of underwater vision profilers (UVP), a camera that can be mounted on a wide range of supports, enabled the quantification the particles vertical flux, the determination of their origin, their link with zooplankton and bacterial communities, their role in mesopelagic remineralisation and oxygen consumption, and the study of the biomass and migration of zooplankton. Studies of the mesopelagic zone and the deep ocean have shown that bottom bacteria are adapted to high pressures and low temperatures and are capable of degrading organic matter, even when considered as refractory, at these depths, unlike surface bacteria whose capacity is limited. Finally, in coastal areas, experiments and in situ observations have shown that the deposition of atmospheric soot modifies carbon transfer pathways (adsorption, aggregation, remineralisation, export) and thus the microbial (viruses and bacteria) functioning of pelagic systems.

-Biogeochemical cycles, biodiversity and ecosystem functionning

A great deal of work has focused on the link between biodiversity on the one hand and biogeochemical cycles, fluxes of carbon and associated biogenic elements (N, Si, Fe, etc.) and even the functioning of ecosystems on the other hand. Biodiversity has been considered at the level of taxonomic groups, but also at the genetic level, as molecular biology tools have been developed and used at an accelerated pace over the last two decades.

In the Southern Ocean, it appears that the type of diatom communities present plays a major role in the stoichiometry of the biological pump and the capacity of this ocean to sequester carbon and the main biogenic elements (Si, N), with distinct associations between bacterial communities and phytoplankton communities playing a crucial role in the recycling of nutrients in the water column. Similarly, the diversity of zooplankton communities determines the mechanisms by which carbon is actively exported. More broadly, iron fertilisation structures biological communities (particularly bacterial, phytoplanktonic and zooplanktonic communities) and their diversity, which in turn conditions the fluxes of carbon and biogenic elements and therefore the efficiency of the biological pump and the ocean capacity to sequester carbon. The use of modern genomics and proteomics tools has revealed taxon-specific strategies for acquiring different forms of C and Fe, indicating how microbes can shape the expression profiles of transcripts and proteins at community level at different seasons and revealing the importance of functional diversity on microbial C and Fe metabolism. They have also made it possible to better discern, within a community of bacteria, which are the most efficient at assimilating iron, and to obtain, at global scale, essential information on the adaptation (evolution) and acclimatisation (physiology) of phytoplankton to iron availability. More specifically concerning the cyanobacteria of the genus Synechococcus, the study of different lines has highlighted physiological and genomic specificities that may correspond to mechanisms of acclimatisation and adaptation to iron deficiency and temperature variations and which, put into a global context, have led on the one hand to the identification of genes specifically present or absent and on the other hand to the demonstration of major differences between the coastal and the open ocean. At global scale, a relationship was demonstrated between phytoplankton genetic diversity and carbon export at 150m, with few taxa generally playing a particular role on a planetary scale or in specific regions.

An analysis of the distribution in the ocean of genes involved in iron metabolism highlighted the diversity of strategies used by microorganisms to acquire iron depending on the surrounding environment (in particular iron concentration and temperature).

In oligotrophic zones, experiments using in situ mesocosms have shown that the diversity of phytoplankton organisms and their associations (diatoms and diazotrophs) determine the fate of these consortia: remineralisation at the surface and support for new phytoplankton production versus export and activation of the biological pump through direct and indirect processes. The role of phytoplankton species diversity on carbon fluxes in these areas has been confirmed by in situ observations. In the Mediterranean Sea, atmospheric deposits of Saharan particles generate competition for new nutrient resources, with heterotrophic bacteria being favoured.

The study of the relationship between dissolved organic matter and bacterial genetic diversity has shown that the composition of resources can shape several facets of bacterial diversity without influencing the phylogenetic composition of communities, suggesting functional redundancy at different taxonomic levels for the degradation of organic matter derived from phytoplankton.

In the benthic coastal zone, it has been shown that, unlike sandy sediments, muddy sediments have a higher biomass and a more intense carbon cycle (production/respiration) but lower biodiversity, and that the species-specific interactions between benthic microalgae and bacteria or meiofauna induce a synergy that stimulates the carbon cycle.

Responses of biogeochemical cycles and the involved organisms to global change and feedbacks

The responses of organisms and associated biogeochemical fluxes to global change have been studied using in vitro experiments, in situ observations and numerical simulations. Numerical simulations at global scale show that, as a result of climate change, the biomass of primary producers and, to a greater extent, that of higher trophic levels will decline over the course of the 21st century. As a result, carbon export and sequestration in the ocean will also decline. Certain processes will nevertheless be mitigated by changes in communities. For example, gelatinous macrozooplankton will be less affected by the reduction in biomass than non-gelatinous macrozooplankton, leading to a smaller reduction in the flow of carbon to the deep ocean in certain areas of the ocean. In the Indian Ocean, other simulations indicate that an anthropogenic input of iron and nitrogen would modify the competition between major phytoplankton families and thus the balance between organic and carbonate carbon pumps, leading to a regional disparity in carbon sequestration. This again illustrates the role of ecosystem dynamics and biodiversity in controlling carbon fluxes. Specific simulations of the impact of certain aspects of global change (increase in temperature and CO₂, input of freshwater and associated matter) on various biogeochemical processes (diurnal cycle and seasonality of oceanic CO₂, CO₂ fluxes at the ocean-atmosphere interface, pH, particle export) have made it possible to reduce the uncertainties in earth system models and IPCC projections at regional and/or global scale.

The study of the impact of ocean acidification to coccolithophores (calcified pelagic species) has shown strong regional disparities, with, for instance, no change in the upwelling of Peru where the species are adapted to strong inter-annual changes in pH, a drop in calcified mass related to a change in morphotype in the Mediterranean Sea where the pH has recently decreased, or disappearance over the last twenty years in another region of the globe. It has also been shown, at a much larger time scale, that gradual increases in CO₂ and temperature over a few million generations lead to greater calcification, implying positive climatic feedback. Such changes have also been studied in culture.

Other in vitro experiments have demonstrated the existence of thermotypes within a clade of Synechoccocus (cyanobacteria) and highlighted physiological and genomic specificities, the latter possibly being involved in adaptation to temperature variations.

Fine scales, large scales and up-/down-scaling: from molecules to the evolution of the planet

The projects funded by the ANR over the last 20 years have covered the whole spectrum of spatial and temporal scales, from the smallest scales and processes (molecule formation, gene detection, cellular mechanisms) to the largest scales and processes (century and million-year scales, planetary scale, Earth evolution). Some have also been interested in the up-/down-scaling and interweaving of spatial and temporal scales.

From molecules to communities

The study of the abiotic (non-biological) production of organic molecules (serpentinisation process) in the deep oceanic lithosphere has made it possible to start an inventory of the diversity and stability of the organic molecules produced, to reveal two new classes of abiotic organic compounds and to describe and isolate new bacterial species capable of using them. This study will enable the better constrain of the carbon cycle in the global ocean, but is also of interest for the study of extraterrestrial life.

Numerous studies have focused on iron metabolism pathways in bacteria and phytoplankton or on the genes responsible for metabolism and regulation of iron deficiency (see also above). For example, current research is dedicated to the metabolic pathways involved in the bacterial reduction of Fe3+ and oxidation of Fe2+ in deep hydrothermal marine ecosystems, with the aim of assessing the capacity of bacteria to alter minerals. A new strain has just been biochemically and genetically characterised.

The study of interactions between viruses and organic aggregates has shown that the latter are ‘factories’ for viruses, which seem to be released into the water column rather than exported to the deep ocean. It has also been shown that marine viruses can infect phytoplankton and thus regulate their populations, and that they possess enzymes capable of degrading the carbohydrates in dissolved organic matter. They therefore play a role in the degradation of this matter and compete with microbial communities by altering their use.
Various studies have looked at the genetic diversity of groups of small marine organisms (prokaryotes, eukaryotes, protists, viruses) at global scale. It has been shown that their spatial distribution can be linked to temperature, iron concentration or depth, but the link between functional diversity and biogeochemical cycles is still often difficult to establish, particularly because of the very large proportion of genes that are still unknown or whose function is unknown.

Intermediate scales and up-/down-scaling

The role of intermediate spatial scales (sub-mesoscales) and temporal scales (calm and storm episodes) on particle fluxes and the structuring and functioning of ecosystems has been extensively studied and taken into account in the models. In particular, a hierarchy of regional ocean models of increasing spatial resolution, the highest resolution of which explicitly resolves the dynamics associated with oceanic eddies, has been set up in order to conduct sensitivity experiments to atmospheric forcing and thus simulate the effect of intensifying winds. By coupling the physical model with a biogeochemical and ecosystem model, it has been possible to model explicitly the effect of ocean eddies on the carbon cycle in the Southern Ocean.

The development and use of spatial remote sensing algorithms for water colour has made it possible to classify seawater bodies in many areas of the global coastal ocean and to understand its decadal evolution at certain pilot sites.

Large spatial and temporal scales

The use of models that simultaneously simulate the climate and the carbon cycle in response to continental drift over the last 50 million years indicated that the position of the continents before 15 My favoured a wetter climate than today (leading to increased continental leaching) for a CO₂ content similar to present days, and to conclude that continental drift predisposed the Earth towards a cold climate well before the onset of the current glacial climate mode.

Similarly, the combination of mineralogical and geochemical tracers and numerical simulations showed that changes in the position of the continents and oceans during the Late Cretaceous led to a change in ocean circulation, favouring better oxygenation of the waters and concomitant with more marked continental alteration, which could have played a major role in the global cooling recorded during this period.

Ongoing work is dedicated to the origin of the biogenic bloom that occurred between the end of the Miocene and the beginning of the Pliocene, a period of global climate change. Based on the compilation of carbonate, silicified and terrigenous sedimentary records, this work shows a global event, but mainly expressed in areas of high productivity, and calls into question current hypotheses.

Interactions between the ocean and other compartments of the Earth system

The French community, through ANR funding, has taken an interest in most ocean interfaces in the study of biogeochemical cycles: continent-ocean (soil wethering, continental inputs), lithosphere-ocean (chemical alteration, serpentinisation), deep earth-ocean (hydrothermal inputs), cryosphere-ocean (water and nutrient inputs), ocean-atmosphere (gas exchange, wind inputs). However, it is the ocean-atmosphere interface that has been the focus of most research, with the emphasis on CO₂ exchanges, in connection with the study of the carbon cycle. Most studies have looked at interfaces in terms of material inputs for (and possibly exchanges with) the ocean. However, a few studies have focused on the ocean contribution to the atmosphere. For example, in situ and in vitro mesocosm experiments enabled to understand which physico-biogeochemical and biological parameters promote the formation of marine aerosols in the Mediterranean atmosphere (primary particles and cloud condensation nuclei). Also, the limitations and co-limitations of iron and copper to the production of DMSP and DMS (the former is a precursor of the latter which, once in the atmosphere, favours the production of white clouds that limit global warming by albedo) by diatoms have been studied at the scale of a species and communities by combining experimental measurements, in situ measurements and modelling. They show that while iron limitation increases the production of DMS and DMSP at cellular scale, this effect is restricted to intertropical regions and the high latitudes of the southern hemisphere at global scale.

2-2: Methodological and technological breakthrough

ANR funding has enabled many projects to make major technological and methodological developments, whether in numerical techniques, experimentation, laboratory measurements, sampling or in situ measurements.

Regarding numerical modelling, considerable progress has been made. In particular, this concerns coupling of physical and biogeochemical models, increase in spatial and temporal resolution, better awareness of sub-mesoscale processes in large-scale models, increase in the diversity of biological compartments and biogeochemical processes taken into account, specific studies of precise processes, dedicated studies of uncertainties, etc. it has been made possible thanks to technological developments that have enabled data-storage volumes and calculation speeds to be deeply improved, and to coupling with experimental and field data. The contribution of the digital sciences has also been marked by the very strong step up, particularly over the last ten years, of artificial intelligence and machine learning. Machine learning, for example, has been widely used in automatic image recognition to recognise not only particle types and sizes and planktonic taxa, but also their functional traits.

Major efforts have also been made over the last 20 years in the field of remote sensing, and more specifically ocean colour, to develop and refine signal inversion and atmospheric-correction algorithms, whether using satellite, airborne, drone or fixed-mount remote sensing, in multi-spectral or hyper-spectral mode, in coastal areas as well as open oceans. These methodological advances, combined with the improved spatial and spectral resolution of recent satellites, now enable precise quantification of biogeochemical and biological parameters such as concentrations of suspended solids, dissolved and particulate organic carbon, phytoplankton and microphytobenthic biomass and production, and even biomass and production of certain taxonomic groups of these microalgae, in the open ocean and for most coastal waters.

Numerous projects have also enabled the development or refinement of proxies for palaeo-oceanographers to refine ocean reconstructions of temperature, CO₂, pH or chemical alteration of the lithosphere using geochemical tools (isotopes of boron, carbon, oxygen, lithium, neodymium, osmium) and/or morphological tools for organisms such as foraminifera and coccolithophores or for minerals. High-pressure and high-temperature experiments, combined with analytical development on the speciation and isotopic composition of hydrogen, are also underway to gain a better understanding of the deep hydrogen cycle. This latest work, coupled with measurements of natural samples, should provide a better estimate of the mass of water contained in the deep Earth.

Hyperbaric technologies (samplers, particle-sink simulators, autosamplers also capable of in situ measurements) have been developed and have shown, for instance, that not taking into account the effect of pressure on bacterial activity in the deep ocean strongly biases carbon budgets. These developments have made the involved scientists international leaders in hyperbaric measurements and knowledge of the meso- and bathypelagic domains.

Hybrid pH sensors combining electrode and spectrophotometer have also been developed and tested in the laboratory and in the field.

While the instrumentation of wild animals has existed for several decades, the miniaturisation of an increasingly wide range of sensors over the last two decades has made possible the instrumentation of seals, for example, and thus acquire a vast amount of data on physical and biogeochemical parameters (temperature, salinity, pressure, light, chlorophyll biomass) in the Southern Ocean, which is difficult to access using conventional means.

Finally, a new generation of ice drilling probe has been designed to enable real-time analysis of methane concentration and water isotopes. This required a completely new method of drilling and management of the chips generated when machining the ice, as well as the miniaturisation of a laser spectrometer.

2-2 Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities. Research in touch with society

Beyond the fundamental interest of the research described above concerning the biogeochemical functioning of the global ocean and its links with the other compartments of the Earth system (atmosphere, continent, lithosphere, cryosphere, deep earth) and other fundamental disciplines (physics, ecology, geology), it is clear that this work is directly linked to major societal issues. One of the main issues addressed over the last 20 years is global warming. The results described above clearly address the ocean capacity to sequester carbon and therefore its ability to mitigate climate change by absorbing and sequestering part of the CO₂ emitted by human activities. Many of these studies have also focused on the role of iron, an element that (co-)limits phytoplankton primary production in many areas of the ocean and therefore the efficiency of the biological carbon pump. Some of this work has also looked at the consequences of global change on the biogeochemical functioning of the ocean, and in particular on changes in its capacity to sequester carbon. In addition, numerous numerical simulations based on the results of oceanographic campaigns and experiments have produced projections for the 21st century. These results and projections have been used directly by the IPCC in its reports for decision-makers and the general public.

Also, in connection with global warming, which is largely due to excess atmospheric CO₂, one of the studies looked at the reactivity of deep biota to the injection of CO₂ into basalt, which was mentioned as a possible technique for storing excess atmospheric CO₂.

On a more anecdotal level, some of the research work described above is also contributing a few pieces to the puzzle of the emergence of life on Earth and potential extra-terrestrial life.
At last, some of this work has been carried out in direct interaction with the national socio-economic fabric: several projects have been carried out with private partners, ranging from the importance of benthic microalgae in aquaculture to the development of hybrid pH sensors. In addition, work on two projects has led directly to the creation of start-ups: one specialised in microalgae-based nutrients and the other in the production of a probe (miniaturised laser spectrometer). 

3- Research perspectives

3-1 For Scientific aspects:

Regarding the ocean capacity to sequester carbon, it is essential to continue studies dedicated to the mesopelagic zone. Indeed, despite real progress made over the past 20 years, the international community is not yet able to constrain the spatial and temporal variability of vertical carbon flux attenuation and thus the efficiency of carbon transport to the deep ocean and its long-term sequestration to the level of needs. However, understanding and being able to finely model this vertical flux is crucial not only for understanding biogeochemical cycles but also for relevant modelling of the long-term climate variability and its prediction till the end of the 21st century. For this achievement, it is necessary to continue studying the different processes involved (export flux from the surface to the mesopelagic zone and type of particles involved, remineralization, aggregation/disaggregation, grazing and faecal pellet production) and to take into account the different biological compartments involved. The influence of vertical migrations of zooplankton, the role of mixotrophs and the understanding of the factors that influence their respective parts of autotrophy and heterotrophy, the role of viruses not only as infectious agents but also as users of dissolved organic matter in competition with bacteria will need to be understood. These needs certainly require technological advances for (direct or indirect) in situ measurements.

More broadly, the biogeochemical role of mixotrophs, diazotrophs (especially in oligotrophic zones) and other main families of phytoplankton, photoheterotrophic bacteria and viruses needs to be better understood and then taken into account in models. The biogeochemical role of oceanic fungi will need to be explored.

The study of the impact of global change on the biogeochemical functioning of ecosystems and its feedback to climate must be continued both through in vitro experiments and through repeated observations in key areas. This is valid for the open ocean as well as the coastal ocean and concerns different facets of global change (excess CO₂, acidification, continental and atmospheric inputs, temperature, including extreme events and their succession, etc.). Ecosystem trajectories and their forcing must be able to be highlighted and projected into the future at multi-decadal scale. The role of calcifying species, which have a dual impact on carbon sink/source balance (calcium carbonate pump in addition to the 'classic' biological pump), must continue to be the subject of dedicated studies.

The study of hydrothermal vents will need to be continued to assess their role in nutrient fertilization of the ocean, their support for biological production and therefore their role in biogeochemical cycles. This concerns shallow vents and their impact on surface primary production, but also deep-sea vents, since they represent biogeochemical and ecological factories.

Mesoscale and sub-mesoscale physical processes and their implications for biogeochemical fluxes and cycles must continue to be studied and their modelling must become as systematic as possible for regional and global models.

Molecular biology has made spectacular advances over the past two decades. However, the use of these tools in biogeochemical research is still in its infancy. A challenge will probably be to identify functional genes to better address the link between genetic diversity and biogeochemical processes from a functional perspective. A better understanding of this link should make possible the monitoring, or even anticipation, of the evolution and possible adaptation of the biogeochemical functions of living organisms in relation to climate change.

3-2 Structuration of the communities:

The projects funded by the ANR and summarized above demonstrate a strong coupling between experimental approaches, observations (field-based or remotely sensed) and modelling. Strong disciplinary coupling (physics/biogeochemistry/ecology in particular) appears. This illustrates the degree of maturity and the structuring of the French oceanographic community.

Surprisingly, only few projects dedicated to coastal areas have been funded by the ANR in 20 years. Their scientific and societal challenges are at least as important as in the open ocean, even if they are not strictly of the same nature. An incentive for coastal communities to submit projects would be required. This could be achieved through a dedicated program.

Biodiversity loss and impacts on the functioning of marine ecosystems

Marine ecosystems are subject to multiple pressures related to human activities that disrupt food webs and threaten human health. The introduction of non-native species, in particular, modifies ecological dynamics, community structure, functions, and ecosystem services. 78 projects co-financed by the ANR, some using molecular approaches such as environmental DNA (eDNA) and genomics to improve species detection and understand adaptation mechanisms to disturbances, have led to major advances in monitoring and predictive modeling, facilitating early detection of changes in marine biodiversity and guiding management policies (Marine Protected Areas) towards the most sensitive areas. Among the research avenues to follow: the integration of cutting-edge technologies such as eDNA and artificial intelligence for better management of marine ecosystems, as well as concrete solutions to limit biodiversity loss, such as habitat restoration and biocontrol techniques.

Yunne-Jai Shin: IRD, Valérie Stiger: UBO and Line le Gall: MNHN

1- Scientific background:

Scientific evidence clearly shows that marine biodiversity is being impacted at unprecedented rates by human activities (fishing, coastal development, pollution) and human-induced climate change (ocean warming, acidification, sea level rise, extreme events). Over the last decade, 66% of the ocean has faced rising cumulative impacts, with only 3% remaining untouched by human pressure. While fishing has remained the most significant driver of biodiversity loss over the past 50 years, climate change effects continue to accelerate.

Coastal ecosystems are under increasing threat as coastal populations grow at a faster rate than the global average. With 75% of megacities now situated along coastlines, more than 2.6 billion people rely on these ecosystems for food, income, and protection. This growing pressure has contributed to the decline of vital ecosystems such as seagrass meadows, mangroves, and coral reefs.

Land-based pollution further compounds these challenges. Since 1980, marine plastic pollution has increased tenfold, harming wildlife through macroplastic ingestion, while microplastics infiltrate food webs, posing risks to human health. Coastal waters also suffer from high levels of metals and persistent organic pollutants, originating from industrial discharge and agricultural runoff, which contaminate marine populations. Excess fertilizers fuel nitrogen and phosphorus runoff, leading to eutrophication and the formation of hypoxic "dead zones." Moreover, ocean and airborne pollutant transport drives these harmful impacts — from plastics to heavy metals — to spread globally, with lasting consequences for both ecosystems and human health.

Biological invasions refer to the introduction and rapid proliferation of an exotic species in a new ecosystem, where it causes ecological imbalances and impacts biodiversity, the economy or human health. These invasions are often encouraged by human activities (for example, trade, aquaculture and transport) and the absence of natural predators in the area of introduction. Introduced species with significant ecological and/or economic consequences are referred to as invasive species. They represent a growing threat, amplified by globalisation and climate change.

The challenges posed by invasive species are manifold and concern four major dimensions: ecological, economic, health and regulatory.

Invasive species cause major disruption to ecosystems and contribute to a reduction in biodiversity (Molnar et al., 2008). Some non-native species modify the abundance and diversity of local populations, influence ecological interactions and accelerate evolutionary processes that alter ecosystem structure, functions and services (Simberloff et al., 2013; Dawson et al., 2017; Blakeslee et al., 2020). In the case of microbial invasive species, these disturbances can include the spread of pathogens affecting local flora and fauna. Moreover, their impact on native ecosystems leads to anthropogenic biotic homogenisation, a process whereby regional biological communities become similar over time (Olden et al., 2018), a phenomenon that is expected to intensify with climate change (Bennett et al., 2021).
The introduction of non-native species can also have major economic repercussions. According to Hulme et al (2009), biological invasions entail considerable costs for the agricultural, forestry and fisheries sectors. Globally, the economic costs of biological invasions have been estimated at US$1,288 billion over the period 1970-2017 (Diagne et al., 2021).

Some invasive species have a direct impact on human health. As disease vectors, they can transmit dangerous pathogens. Some are also highly allergenic, causing severe respiratory allergies and high costs for the healthcare system. In addition, some invasive microalgae produce toxins that can contaminate the food chain and affect human consumption.
In response to these threats, a number of laws and regulations have been introduced to limit the spread of invasive species. At international level, the Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention), adopted in 2004, establishes global rules aimed at reducing the transfer of alien species via ships' ballast water. At European level, Regulation 1143/2014 establishes a list of invasive alien species of concern for the European Union, banning their import, sale and transport in order to limit their spread. In France, the National Action Plan (PNA) sets out strategies for the prevention, early detection and eradication of certain invasive species, based on monitoring and management actions tailored to the different environments concerned.

Despite these initiatives, the fight against invasive species remains a major challenge, requiring international coordination and ongoing efforts. In Europe, more than 14,000 non-native species have been introduced and established over the centuries as a result of trade and human transport (EASIN, 2022).

A new approach with the challenges of understanding marine biodiversity and the contribution of eDNA and genomics. Marine biodiversity is an immense reservoir of biological diversity, playing an essential role in the functioning of ecosystems and the maintenance of ecosystem services. With 240,000 species currently described, our knowledge of this biodiversity remains incomplete, and around 2,000 new species are described each year. The extent of underestimated genetic and specific diversity limits our ability to develop effective conservation strategies. Environmental DNA (eDNA) and genomics are the tools of choice for filling these gaps. eDNA makes it possible to identify the presence of organisms from genetic traces left in the environment (water, sediment, ice, etc.), without having to physically capture them. This approach is particularly valuable for detecting rare, cryptic or low-abundance species, and facilitates the temporal and spatial monitoring of marine communities. However, to be able to assign a molecular sequence to an organism, it is essential to have a reference database with a robust taxonomy, which is currently far from the case for most organisms.
Genomics approaches, favoured by the advent of high-throughput sequencing technologies, provide access to the genetic information of individual species, revealing little-known biological functions. They also make it possible to study the mechanisms of adaptation to changing environmental conditions, in particular by analysing mutations and genetic variations influencing resistance to stress, reproduction and population dynamics. This knowledge is essential both for understanding the relationships between marine organisms and for anticipating the impact of climate change and human pressures on marine ecosystems.

2- Main Contributions of the French Communities through ANR co-funding:

Scientific advancements, by showing that all facets of biodiversity are impacted by human pressures and do matter for ecosystem functioning, have been pivotal in shaping how the Convention on Biological Diversity (CBD) addresses biodiversity conservation across genetic, species, and ecosystem levels.

For addressing marine genetic diversity, genomic research and techniques like environmental DNA (eDNA) and genetic sequencing allow scientists to monitor marine species’ genetic variation, which is essential for understanding their adaptation capacity to changing ocean conditions, such as ocean acidification and warming, and emerging diseases and pollution. These technics are used in the ongoing DockEvol project, specifically haplotagging genome sequencing, combined with condition index assessments, and microbiome profiling, alongside characterization of abiotic and biotic environmental factors through eDNA metabarcoding. These data will inform the construction of fitness landscape models in highly anthropized port environments where exotic and native species sometimes hybridize and interbreed, hence changing population dynamics and demography (Touchard et al. 2024). Based on massive eDNA sampling and analyses, the ATLASea research programme is one of the winners of the PEPR (Priority Research Projects and Equipment) exploratory programmes, aimed at structuring emerging scientific communities. Co-piloted by CNRS and CEA and funded by France 2030 over 8 years, ATLASea aims to sequence the genomes of 4,500 eukaryotic marine species, including molluscs, crustaceans, annelids, cnidarians, ascidians, unicellular and multicellular algae, sponges and fish. This represents around a third of known marine species in France and the overseas territories. The data collected will be made freely available, enriching biodiversity inventories and contributing to international sequencing efforts under the aegis of the Earth Biogenome Project (EBP). Integrating these technologies into marine biodiversity research presents a number of challenges. On the one hand, standardisation of methods and accessibility to reference databases are essential to guarantee reliable identifications. Secondly, managing and analysing massive volumes of genomic data requires advances in bioinformatics and artificial intelligence. Finally, the use of these techniques raises ethical and legal questions about the protection of genetic resources and the equitable sharing of knowledge.In short, eDNA and genomics are essential tools for improving our understanding of marine biodiversity, better assessing its conservation status and anticipating the impact of global change on ocean ecosystems. Their development and integration into marine research and monitoring programmes are therefore priorities for sustainable ocean management.

The focus on genetic diversity is reflected in the CBD’s Target 13, which aims to prevent genetic erosion in both wild marine species and aquaculture species, ensuring their long-term resilience.

At the species level, scientific innovations such as satellite tracking, underwater acoustic monitoring, and AI-powered biodiversity assessments have significantly improved our ability to study the dynamics of marine species in relation to their biotic and abiotic environment. The deployment of novel observation technics at different spatio-temporal scales has helped to better explain ecological processes, and has increased inference capacities in varying and perturbed environments. Satellite tracking allows scientists to follow the migratory patterns of vulnerable marine animals, such as sea turtles, birds, whales, and sharks, which is vital for protecting migratory routes and critical habitats. Underwater acoustic monitoring provides key data on species abundance and behavior, especially in hard-to-reach marine areas. The project TOPINEME innovated by combining different layers of data from the physics, plankton up to fish, fishers and top predators, for example using GPS data loggers for tracking seabirds foraging trajectories, acoustic backscattering data for modelling prey abundance and schooling behaviour. They showed how the variability in the physical environment can change the accessibility of prey to seabirds, hence changing seabird species composition by bottom-up control (Boyd et al. 2015). The TOPP-PATCHES project used accelerometers coupled with a new generation of Argos CTD tags recording dissolved oxygen concentration to assess fine-scale feeding success of elephant seals as a function of oceanographic conditions (Vacquié-Garcia et al. 2015). Artificial intelligence (AI) has also revolutionized marine biodiversity monitoring by processing vast amounts of data from sensors, underwater cameras, and remote sensing tools (Future-OBS, FISH-PREDICT). AI algorithms can identify and track species in real time, helping decision-makers and managers to meet the goals of halting extinctions and restoring threatened marine populations (Goal A, Target 4 of the CBD).

For marine ecosystem diversity, advances in remote sensing and ecosystem modelling have enhanced our ability to monitor and assess the health of marine environments, regarding habitat degradation, carbon storage, foodweb maintenance and ecosystem connectivity. Remote sensing through satellites and drones allows for the large-scale assessment of marine ecosystems, providing valuable insights into marine productivity, habitat degradation, water quality, and temperature changes. For example, the APEX project proposes an innovative automatic prey observation system using drones equipped with an echo sounder to map the spatio-temporal distribution of prey for seabirds. Integrated ecosystem and ocean modelling is crucial in predicting the impacts of climate change on marine ecosystems, including shifts in species distributions and abundances, coral bleaching, and the expansion of hypoxic “dead zones.” These models are essential in guiding restoration efforts, such as the CBD ambitious “30 by 30” target, aiming to protect 30% of of the ocean by 2030.

In the last decade, biodiversity science has made considerable progress in building integrated models and scenarios that link multiple drivers of global change to ecosystem functioning from the physics, through biogeochemistry, plankton up to fish biodiversity and fisheries. These models and scenarios provide decision-makers with visions for the future, and exploration of actionable management, economic, policy options for the future of the ocean. The development of state-of-the art end-to-end modelling tools makes the core of the CIGOEFF, SOMBEE and MEDIATION projects. Significantly, two of the developed models (APECOSM, OSMOSE) have been selected in the top ten models (out of 62) by an independent expert study tendered by the European Commission, for the implementation of the European Digital Twin of the Ocean that aims to support decision-making capabilities to implement EU policies like the Marine Strategy Framework Directive (DGRI and AZTI, 2022). In addition, the french IPSL and APECOSM ocean models have been used in a major ensemble modelling endeavour reported in IPBES and IPCC latest reports, showing that, by the end of the century, climate change is projected to decrease net primary production (by ca. 1.9% under the low greenhouse gas emission scenario, RCP2.6 and ca. 7.5% in the high emission scenario, RCP8.5), and secondary production up to fish biomass (by 7% and 19% under RCP2.6 and RCP8.5, respectively) (Tittensor et al. 2021).

By integrating the scientific findings, tools and data into its framework, the CBD ensures that its marine conservation strategies remain data-driven, evidence-based, and adaptive to the challenges posed by climate change and human impacts. These advancements enable more targeted, effective conservation measures and provide the necessary information to monitor and adjust efforts to protect marine biodiversity in the face of an accelerating global environmental crisis.

The ANR DockEvol project explores the concept of biological portuarisation, which refers to the evolution of marine species in port environments that have been heavily modified by human activities. This project aims to understand how these specific conditions influence the adaptation and evolution of species, with a particular focus on ascidians (Touchard et al., 2024).

This research shows that climate change and anthropogenic modifications to ecosystems favour invasive species, threatening native biodiversity and sustainably transforming coastal and port ecosystems.

Invasive species are a key topic in research funded by the French National Research Agency (ANR), which supports projects aimed at better understanding and limiting their impacts. As part of this, the ANR is funding a number of studies focusing on the following themes:

• Understanding the mechanisms by which invasive species are introduced, established and spread, taking into account global change. The ANR DEVODIVERSITY project, which studies the invasive potential of chordates, explores the role of colonial and solitary ascidians, some species of which have developed reproductive and regenerative strategies that enhance their invasive capacity. The ANR DockEvol project is looking at the identification and adaptive evolution of species, both native and introduced, in port environments, with a focus on ascidians living in these anthropized environments. The ANR REMOVE DISEASE project has demonstrated that rats, mice and cats introduced to oceanic islands are vectors of pathogens, affecting the health of seabirds. Finally, the impact of climate change on invasive macro-algae has been studied, in the ANR INVASIVES project, which studied the ecophysiology and chemical ecology of invasive marine macroalgae in Europe, from Portugal to Norway. The results highlighted a chemical adaptation of these species, influencing their expansion in a context of climate change (Surget et al., 2017). This ANR-funded research is helping to improve our understanding of the dynamics of biological invasions, to anticipate how they will evolve in the face of environmental change, and to identify solutions for limiting their impact on biodiversity and ecosystems.
• Assessing the impact of invasive species on ecosystems, biodiversity and ecosystem services is based on experimental approaches. Researchers manipulate ecosystems by eradicating invasive species, then observe the consequences for native species and ecological balances. As part of the ANR INVASIVES project, removal experiments were carried out on several species of invasive macroalgae present in rocky intertidal environments. The results showed an increase in floristic diversity on the manipulated sites, underlining the negative role of invasive species in the decline of biodiversity. However, these effects vary depending on the environment. In intertidal mudflats, the presence of the red macroalga Gracilaria vermiculophylla has, on the contrary, favoured the diversity of burrowing animals and modified the food web, benefiting species that consume the invasive alga (Davoult et al., 2017).

Two other ANR projects are looking at the impact of invasive mammals on island ecosystems: ANR REMOVE_DISEASE is studying the eradication of rats, mice and cats and its effects on the health of seabirds. Similarly, ANR InvEcoF is analysing the impact of invasive rats on the functional role of land crabs and seabirds in the atolls of French Polynesia. These two projects have shown that reducing populations of invasive mammals contributes to the preservation and health of seabird populations.

The ANR SEAPROLIF project focused on chemical interactions between invasive macroalgae and native species. It studied the impact of metabolites produced by the invasive red alga Asparagopsis taxiformis on the microbiota of native species (Greff et al., 2014). He also highlighted a change in the metabolome of A. taxiformis when it comes into contact with the native coral Astroides calycularis (Greff et al., 2017), highlighting the complex chemical interactions influencing local biodiversity.

This research shows that invasive species have variable impacts on ecosystems, potentially reducing biodiversity or, in some cases, altering food webs in unexpected ways. It also highlights the importance of chemical interactions in invasion mechanisms and the impact of invasive mammals on island fauna.

Developing monitoring and management tools to limit the spread of invasive species is a major challenge.

In the ANR DockEvol project, biomonitoring tools based on environmental DNA are being developed. These approaches make it possible to design a model of fitness landscapes, adjusted to genotype-phenotype maps that take account of environmental variations.
A key advance in this field is the study by Milián-García et al (2025), which constitutes the first molecular biomonitoring research applied to international shipping containers. Carried out in Canada, this study aims to detect and identify invasive species before they are dispersed, paving the way for better prevention of biological invasions.

Studying the fate of invasive species in the context of global change. Global warming is a key factor in the expansion of invasive species. Because of their ability to adapt rapidly to new environmental conditions, these species benefit from global change, unlike native species, which are generally specialised in their original habitat and less resilient to disturbance, as has been shown in marine macroalgae (Le Lann et al., 2012; Tanniou et al., 2014).

In the ANR INVASIVES project, experiments in thermostatically controlled tanks were carried out on pairs of invasive/native species, testing different temperatures and salinities. The results showed that the invasive brown macroalga Sargassum muticum is highly resistant to increases in temperature and dilution of seawater, unlike the native species Cystoseira baccata, which does not tolerate these environmental variations. These observations confirm that climate change could favour the expansion of invasive species to the detriment of local species.

The ANR DockEvol project explores the concept of biological portuarisation, which refers to the evolution of marine species in port environments that have been heavily modified by human activities. This project aims to understand how these specific conditions influence the adaptation and evolution of species, with a particular focus on ascidians (Touchard et al., 2024).

This research shows that climate change and anthropogenic modifications to ecosystems favour invasive species, threatening native biodiversity and sustainably transforming coastal and port ecosystems.

All of this research and the many results obtained are helping to guide public conservation policies and strengthen strategies to combat biological invasions. Faced with the growing challenges of climate change and globalisation, this work is essential to anticipate, manage and mitigate the impact of invasive species on biodiversity and ecosystems.

3- Research perspectives:

Invasive species are a major scientific challenge, requiring interdisciplinary approaches to better understand, anticipate and manage their spread. Current and future research into these species is divided into several strategic areas:

• Understanding invasion mechanisms. The study of invasion dynamics is based on three main areas: a) identifying the factors favouring the establishment and dispersal of invasive species, which is made possible by analysing the biological and ecological traits of invasive species and comparing them with native species. b) assessing the effects of global warming on the expansion of invasive species into new regions. And c) to identify the influence of human activities on invasions, which means studying the vectors of introduction (maritime transport, international trade, aquariology, urbanisation). A focus on port ecosystems, where species evolve in a specific abiotic environment and cohabit with a novel assemblage of invasive and indigenous species, is a promising avenue.
• Genetic and biotechnological approaches. Technological advances offer new tools for detecting and monitoring invasive species. Environmental DNA (eDNA) is an area of interest because it enables early detection of invasive species before they become a problem. Genomics and epigenetics can also be used to analyse the rapid adaptation of invasive species to their new environment.
• New management and control strategies. Several solutions are being developed to limit the impact of invasive species: Starting with biocontrol methods, in which natural predators, pathogens or competitors are sought out and used to regulate invasive populations. There is also ecological restoration, which enables degraded ecosystems to be rehabilitated after an invasive species has been eradicated.
• Integration of the social and economic sciences. Biological invasions are not just an ecological issue; they also have economic and societal repercussions. It is important to assess the economic costs of invasions: analysis of losses in the agricultural, fisheries and forestry sectors, and in terrestrial and marine environments. Another priority is the social acceptability of control measures, as some invasive species are perceived differently by managers and the general public, which can make their management more complex. In conclusion, research into invasive species is not limited to their current management; it aims to anticipate future invasions, develop innovative tools and integrate the economic and social dimensions into control strategies. Against a backdrop of climate change and increasing global trade, the prevention and monitoring of biological invasions are essential to preserve ecosystems, reduce their economic impact and protect human health. Finally, informing the public and raising awareness remains a priority, to encourage good practice and limit accidental introductions.

Given the complexity of marine ecosystems and their deep interconnections with human societies — now recognized as socio-ecosystems — along with the multiple drivers of biodiversity loss and the need to address biodiversity at genetic, species, and ecosystem levels, scientific research is inevitably moving toward more interdisciplinary, integrated approaches. These approaches combine diverse techniques and tools, from environmental genomics and remote sensing to social science methods, to capture the full complexity of these systems and design more effective, adaptive conservation strategies.

Facing increasing human pressures, long-term observation of coastal socio-ecosystems is essential to understand their dynamics, manage risks, and assess public policies. Despite progress in ocean observation, disciplinary fragmentation still prevents a holistic understanding of these complex systems. Twenty years ago, the CHALOUPE project was a pioneer in integrating different disciplines, tools, and data types into its analysis of marine biodiversity loss, looking not only at historical data analyses but also at prospective viability analyses. The recent ongoing FUTURE-Obs project aims to develop multi-scale, multi-disciplinary observation strategies, combining traditional methods with innovations like environmental genomics, in situ imaging for biodiversity, and social media data for human activity analysis. The diversity and heterogeneity of the data will support the development of new indicators using AI tools.

Developing transdisciplinary approaches — where scientists collaborate with stakeholders such as decision-makers, managers, fishers, tourism operators, renewable energy developers, and coastal communities — can greatly enhance the planning and implementation of ocean-related measures. By merging ecological data, oceanographic modelling, and socioeconomic insights with local and sector-specific knowledge, these inclusive approaches can support complex processes such as marine spatial planning that better balances conservation (e.g., marine protected areas), exploitation, marine renewable energy development, and potential sectoral conflicts like those between tourism and fisheries. Even though transdisciplinary projects have been developed for a long time, they were either led by social scientists, or were specific to a marine sector of activities (fishing for example). Recent projects such as FUTURISKS, MaHeWa, REMOVE_DISEASE, SOMBEE develop significant stakeholder engagement activities, in a way that integrates different scientific disciplines and a diversity of stakeholders. Engaging stakeholders throughout the scientific process fosters co-produced knowledge, ensuring measures are not only scientifically robust but also reflect local realities. It eventually aims to improve the quality and legitimacy of decisions and thus to increase stakeholder buy-in, fostering a sense of ownership and responsibility. As a result, management measures are more likely to be respected and effectively implemented, ensuring both ecological and socio-economic goals are met.

SEAWEED RESEARCH

Macro-algae, essential to coastal ecosystems and the carbon cycle, have strong ecological and biotechnological potential. 48 ANR projects have led to major advances in genomic sequencing, understanding responses to climate change, valorizing the bioactive properties of algae, and modeling their proliferation. Governed by specific regulations according to their use (fishing, cultivation, processing), they are part of the blue bioeconomy. Research perspectives aim to develop sustainable cultivation, zero-waste biorefineries, and strengthen innovation in the service of ecological transition and food security.

Claire Hellio UBO and Philippe Potin CNRS, Sb Roscoff

1) Scientific background

Research on macroalgae has experienced significant advancements over the past two decades, driven by the growing recognition of its biological, ecological, biotechnological and economic importance. Seaweeds – including red, green, and brown macroalgae – are primary producers and foundation species, playing vital roles in coastal ecosystems, providing habitat, sequestering carbon, and cycling nutrients (Filbee-Dexter et al, 2024). Their applications span numerous industries, including food, feed and plant biostimulants, cosmetics, pharmaceuticals, and bioplastics. Here, we summarize the state of the art in macroalgae research, highlighting key breakthroughs.

Over the last 20 years, application of modern ‘omic and genetic methods has significantly advanced our understanding of the origin, evolution, and metabolic potential of multicellular algae, as well as their diverse modes of sexual reproduction (Brodie et al., 2017). Genome-enabled studies have revealed the significance of specific transcription factors, small RNAs, epigenetics, and transposable elements in algal plasticity. Linking hypotheses generated from genomic analyses to specific activities and/or phenotypes is facilitating the development of a new range of tools for algal studies and breeding. New generation sequencing methods applied to seaweeds have also accelerated the development of population genetics studies which have provided new knowledge on the genetic structure, diversity and mating systems for numerous species of ecological and/or economic importance.

Significant progress has been made in understanding the physiological responses of seaweeds to climate-induced stressors. Experimental studies and genomic approaches have provided insights into mechanisms of thermal tolerance, acidification resilience, and adaptation to changing salinity. Emerging evidence shows also that their microbiota plays an important role in the seaweed nitrogen fixation, vitamin uptake, development, stress response and reproduction. The concept of holobiont has also been applied to seaweeds which are no longer seen as independent organisms, but fully interacting with their associated microbiomes (Saha et al., 2024).

Considerable progress has been made in understanding the ecological roles of seaweeds, particularly in the context of global change. Concurrently, the impacts of environmental stressors, such as ocean warming, acidification, and pollution, on seaweed resilience and community structure have been extensively studied. Studies have demonstrated their importance as primary producers and their contributions to detrital food chains, influencing coastal productivity and supporting marine biodiversity. Research has also started to decipher the contribution of macroalgal habitats, such as kelp forests or seaweed farming, to blue carbon sequestration (Krause-Jensen & Duarte, 2016; Pessarrodona et al., 2024). Studies have quantified their capacity to capture and store atmospheric CO2 transferred in the ocean. Advances in ecological monitoring and modelling have enhanced the understanding of seaweed biodiversity and the dynamics of their habitats. Remote sensing and GIS technologies have been widely adopted to map seaweed distribution on regional and global scales. Policy frameworks now increasingly recognize the importance of conserving seaweed ecosystems for biodiversity and climate regulation. Research has further elucidated the role of seaweeds in marine food webs and in the context of coastal eutrophication. Sudden beaching of huge seaweed masses smother the coastline and form rotting piles on the shore. The number of reports of these events in previously unaffected areas has increased worldwide in recent years.

Regarding biotechnological advances, seaweed aquaculture has undergone rapid development, becoming a major focus of research due to its potential for sustainable biomass production. Innovations in cultivation techniques, such as integrated multi-trophic aquaculture (IMTA) systems, aimed to improve productivity and minimize environmental impacts. The discovery and characterization of bioactive compounds in macroalgae have expanded their applications in pharmaceuticals, nutraceuticals, and cosmetics. Compounds such as fucoidans, carrageenans, and phlorotannins have been prove anti-inflammatory, antiviral, and antioxidant properties, leading to potential therapeutic applications and numerous developments of actives for the cosmetic industry. Moreover, seaweeds have gained attention as a renewable resource for bio-solutions in agriculture. Some research has also focused on optimizing fermentation processes to produce bioethanol and biogas from seaweed biomass. Additionally, polysaccharides extracted from seaweeds are being explored as feedstocks for biodegradable plastics or surfactants, offering eco-friendly alternatives to oil-based materials and chemicals.

The global seaweed industry has seen major growth, with research supporting the development of value chains for food, feed, and industrial products. It feeds the fastest growing aquaculture sector, employing millions of people worldwide. Collaboration between scientists, policymakers, and industry stakeholders has been instrumental in promoting sustainable practices. Research data has successfully influenced policy decisions, emphasizing the need for marine spatial planning to balance seaweed cultivation with environmental conservation. Additionally, international collaborations have facilitated knowledge sharing and capacity building in emerging seaweed-producing regions.

2) Main Contributions of the French Communities through ANR (co)funding (Action plan and France 2030)

The projects funded by the French National Research Agency (ANR) have significantly contributed to advancing knowledge on algae by exploring various aspects of their ecology, biotechnology, and ecosystem services.

2-1 Scientific progress; cutting edge science

The availability of genome sequence information from both brown (Cock et al, 2010, Ye et al, 2015, Denoeud et al 2024) and red macroalgae (Collén et al, 2013, Lipinska et al, 2023) has allowed some comparative analyses, but experimental investigation of the molecular basis of developmental processes in these algae is essential. The recent demonstration within [Bi-Cycle] that key developmental genes can be identified in the brown algal model Ectocarpus using a forward genetic approach represents a first step towards the emergence of experimental macroalgal developmental biology. Following Bi-Cycle, the project EpiCycle have completed an extensive characterisation of chromatin features in Ectocarpus. In addition to addressing life-cycle-related questions, these studies provided several new insights into chromatin function in the brown algae

Together with several other ANR-funded projects, IDEALG has contributed to the sequencing and analysis of reference genomes for dozens of brown and red algae and more than a hundred genomes of associated bacteria. This achievement was a major breakthrough for the biology of macroalgae. Based on these resources, genotyping tools have been developed for several species, either microsatellite markers or SNPs whose identification has been facilitated by new sequencing technologies. In parallel, phenotyping efforts have also been developed through culture, physiology and biochemistry tools to help determine the traits of interest for varietal selection. These tools were used in the framework of IDEALG, as well as in other projects on new species based on data acquired on the model species Ectocarpus. Over the course of 10 years, IDEALG has developed modules for processing genomic, genetic, biological and chemical information that have also contributed to developing biotechnological tools for projects completed with companies on a national and international scale. More than 450 recombinant proteins have been expressed by the SBR platforms, mainly enzymes for the degradation of algal biomass from specialized marine bacteria, but also more than ten algal proteins involved in the synthesis pathways of metabolites of interest such as phlorotannins, sterols, halogenated compounds or derivatives of oxidized fatty acids. Functional genetics tools for non-model bacteria or brown algae are also revolutionizing approaches to identify new functions or reveal new aspects of algae biology and metabolism. Made available to the scientific community within the national biology infrastructure European Marine Biological Resource Centre EMBRC-Fr, these results and these biological and genetic resources provide a better understanding of the physiology, reproduction, metabolism and interactions of algae with their environment.

Calcareous red algae represent an important functional group in the coral reef ecosystem and yet knowledge remains fragmented. The results obtained during BIOCARRA show the relevance of integrative taxonomy approach (morphology, ecology and genetics). 

2-2 Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities

Some major seaweed compounds such as sulphated polysaccharides and fibers have also found commercial applications in agriculture, animal farming, medical field and to provide substitute to oil-based products such as surfactant developed by the start-up Surfact’green in Rennes. Projects such as the Labcom ALGAHealth and Anti Foul provided solutions close to the market in their respective fields.

Biomimetism and green chemistry approaches are very promising research strategies for the discovery of new antifouling compounds. ANTI-FOUL focused on the red alga Sphaerococcus coronopifolius, which is known as a producer of bioactive secondary metabolites. Fifteen compounds, including bromosphaerol, were tested against key marine biofoulers. This investigation also revealed that two compounds, sphaerococcinol A and 14R-hydroxy-13,14-dihydro-sphaerococcinol A, were the most potent compounds without toxicity towards oyster larvae (Quemener et al. 2021).

The evaluation of the potential for producing bioethanol from cellulosic green seaweed and the proof of technical concept and sustainability were investigated during GreenAlgOhol. Life Cycle Analysis of the whole system helped identify the main aspects requiring optimization, in particular with regard to algae cultivation. The project also led to the identification and production of new types of polysaccharides and to the discovery of novel enzymes involved in the degradation of algal polysaccharides.

The portfolio of seaweed-specific enzymes coming from the ANR-funded projects Breakingalg, that forms the basis for the creation of the start-up “Aber Actives” based in the small coastal town of Roscoff, has considerably enriched knowledge, in particular by making it possible to use these enzymes to generate bioactives for markets in cosmetics, agriculture and nutraceuticals.

The valorization of FUCOTHROMBO through the production of medical grade LMWF fucoidan by Algues et Mer providing economic revenues and high skills jobs on the remote Ushant Island (Finisitère, Brittany), allowed this SME to gain international leadership in its preparation and marketing, and to develop new applications in collaboration with companies specialized in nuclear imaging, Nuclear Magnetic Resonance, ultrasound and with a pharmaceutical company for a therapeutic application. 

Monitoring & management of invasive macroalgae and valorization strategies: monitoring and managing invasive macroalgae, such as Sargassum and Ulva,  has become increasingly important to mitigate their environmental impact. Fine remote sensing technologies and advanced modeling tools are still needed to accurately track algal blooms and predict large-scale strandings. Early detection will be essential for more effective responses and better management of affected ecosystems. It will be important as well to keep on working on valorization strategies help to reduce waste while also creating sustainable resources. By focusing on these areas, future research could provide the scientific, technological, and policy-based solutions needed to address the challenges posed by invasive macroalgae, turning a potential environmental threat into an opportunity for sustainable innovation.

Yet, wild seaweed communities are predicted to lose up to 71% of their current distribution by 2100, either through overharvesting or climate-driven impacts, such as pollution, invasive species or pest and disease outbreaks. Therefore, interdisciplinary projects such as ECOKELP, and in its continuation IDEALG were anticipating these consequences and provided a forum to disseminate research results and transfer knowledge toward ecosystem management, Marine-protected areas and marine spatial planning. 

A major breakthrough during the last decade for seaweed-processing companies was the access to novel biotechnological developments. A major methodological breakthrough within projects ECOKELP and IDEALG was the need to co-construct research and development projects with their main stakeholders. This led to the many new collaborative projects funded by EMF (EMFAF) grants to develop seaweed cultivation associated with shellfish farming and piloted by professional organisations from several coastal regions across France.

3) Research perspectives coming out of the ANR (co)funded projects

3-1 For Scientific aspects

Despite remarkable progress, challenges remain in seaweed basic research. These include:

• Deciphering biological processes behind the production of active compounds
• Addressing knowledge gaps in the carbon dynamics of seaweed ecosystems and their contributions to global carbon budgets.
• Understanding the long-term ecological impacts of large-scale seaweed farming.
• Enhancing genetic resources for selective breeding and conservation.

Apart from commercial or academic concerns, the impacts of a warming climate on algal health and the role of these taxa as biomarkers of environmental change are also of paramount importance. Future research should prioritize multidisciplinary approaches, integrating biological, ecological, biotechnological, and socioeconomic perspectives to unlock the full potential of seaweeds in addressing global challenges such as climate change, food security, and sustainability for a circular bioeconomy.

The recent development of CRISPR-Cas9 methodology for brown (Badis et al., 2021) and green macroalgae (Ichihara et al, 2022) together with the other tools and resources currently available for the model brown alga Ectocarpus, and the genus Ulva provide the means to deploy the functional genomics approaches necessary to address numerous biological questions.

Research on macroalgae is rapidly expanding due to their potential contributions to the blue bioeconomy, ecological transition and biotechnological innovations. 

3-2 For Innovation as increase the TRL 

One major requirement for the scale-up of the seaweed sector is the development of replicable and cost-effective cultivation technologies to meet a growing demand.

Several key research areas are emerging :

• Seaweed breeding and optimization of sustainable aquaculture practises: Developing improved seaweed strains with higher growth rates, increased disease resistance, and enhanced adaptability to environmental changes (such as temperature fluctuations and ocean acidification) will provide significant competitive advantage to the seaweed market, ensuring higher yields, improved resilience and more sustainable production ; Moreover, improved biobanks and culture techniques will enable large-scale propagation of high-performing seaweed strains, ensuring genetic safety and disease-free seedlings. This method supports the sustainable supply of juvenile seaweed, reducing reliance on wild populations and ensuring year-round production. Breeding programs which are tailoring seaweed strains will significantly contribute to meet industry-specific needs such as high-protein strains for alternative proteins in food applications, enhanced polysaccharide content for bioplastics and pharmaceutical would provide a significant progress.
• Innovative cultivation techniques in macroalgae farming:  Advancements in artificial intelligence (AI) has already started to revolutionize macroalgae farming, making production more efficient, scalable, and sustainable. The further development of such technologies will contribute to optimize growth conditions (AI-powered sensors and imaging systems continuously monitor seaweed growth, detecting variations in biomass accumulation and identifying optimal harvest times) and to enhance disease management and stress detection (machine learning models analyze environmental data to predict and prevent disease outbreaks, reducing the need for chemical interventions).
• Biorefineries and zero waste approach: seaweed biorefineries involve extracting multiple high-value products from the biomass through various processes, such as fermentation, enzymatic treatment, and pyrolysis, while ensuring that little to no waste is produced in the process. There are three main challenges to overcome to ensure that the success of biorefineries: technological development of the processes for extracting, converting, and valorizing seaweed  (innovation in methods such as enzyme-assisted extraction, fermentation, and conversion technologies is crucial to improving efficiency and reducing costs), scalability (ensuring that the processes are compatible with the industrial scale), and  green chemistry) and green chemistry (green chemistry principles must be integrated into the entire process, from raw material to final product, to ensure that the biorefinery operates in an environmentally responsible manner). By addressing these interconnected challenges, seaweed biorefineries can become a cornerstone of the green economy, producing high-value, sustainable products while minimizing their environmental impact. As research, technology, and sustainable practices continue to evolve, the vision of a global, circular seaweed-based bioeconomy becomes increasingly achievable.

3-3 Structuration of the communities: at the national level, at the European level and/or at the international dimension

In France, the research on seaweed is structured through a combination of academic institutions, governmental agencies, and private-sector collaborations. Key actors include the French National Centre for Scientific Research (CNRS), the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), the National Natural History Museum (MNHN), various universities with marine biology and biotechnological research programs and some technical centers developing seaweed valorisation or aquaculture. National funding is provided through agencies such the Agence Nationale de la Recherche (ANR), supporting projects on seaweed applications in food, biofuels, and pharmaceuticals. Some Regional Councils provide also a long-lasting support to the seaweed research. A national roadmap is now launched to implement the EU Algae initiative in France and will likely enhance the efforts of the Funding Agencies on targeted research goals. Additionally, industry clusters such as Pôle Mer Bretagne Atlantique foster collaboration between researchers and companies in algal biotechnology. 
At the European level, research on seaweed is structured through major collaborative frameworks, particularly under the Horizon Europe program, which funds projects on marine biodiversity, blue economy, and sustainable aquaculture. The European Algae Biomass Association (EABA) acted as a key platform connecting academia, industry, and policymakers and it is now helped by other organisations to build the EU4 Algae platform that is implementing the EU Algae Initiative. Initiatives like GENIALG (Genetic diversity exploitation for innovative macro-algae biorefinery) and Seaweed for Europe promote large-scale industrial applications and sustainable harvesting techniques. Furthermore, the Joint Programming Initiative on Healthy and Productive Seas and Oceans (JPI Oceans) supports transnational research on seaweed’s role in carbon sequestration, climate adaptation, and ecosystem services, and, the Sustainable Blue Economy Partnership represents an unprecedent effort of 74 Partner institutions from 30 countries and the European Commission to pool research and innovation investments and align national programmes at pan-European scale. 

Globally, seaweed research is expanding, with contributions from United Nations organizations like the Food and Agriculture Organization (FAO), which provides guidelines on sustainable seaweed farming. The Global Seaweed SuperSTAR project, led by the United Nations University and World Bank, supports sustainable seaweed production in developing countries. Countries such as Japan, China, and South Korea lead in large-scale cultivation and industrial applications, often collaborating with European and American research institutions. Global networks such as the International Seaweed Association (ISA) and the Global Seaweed Coalition co-funded by CNRS in France, UN Global Compact and the Lloyd’s Register Foundation facilitate knowledge exchange on seaweed genetics, cultivation methods, and novel biotechnological applications, ensuring a coordinated international effort in seaweed research. These initiatives would lead to the launch of a UN Task Force that will be created by the endorsement of the Republic of South Korea and Madagascar and other states that will engage in the sustainable development of a global seaweed sector.

The structuration of seaweed research operates at multiple levels, ensuring that scientific advances align with national priorities, European policy frameworks, and international sustainability goals. Increased collaboration between these levels is crucial for developing innovative and sustainable uses of seaweed in food security, climate mitigation, and the bioeconomy. An important instrument to reach such ambition will be to create International Research Centres following the examples of the main agricultural crops with regional hubs. Such an initiative was announced in 2024 by the Indonesian Government to operate an International Tropical Seaweed Resilience Institute (https://hatchinnovationservices.com/tropical-resilience-center-report). EMBRC could support the hub for such a centre for European seaweeds.

PHYTOPLANCTON

Appreciated for their rapid growth and rich composition in bioactive compounds, microalgae have shown their potential in many fields for biotechnological applications. 93 projects supported by the ANR have led to significant advances, particularly in the production of biofuels, biodegradable plastics, and the discovery of high-value pharmaceutical compounds through the use of technologies such as genetic engineering (CRISPR-Cas9) and automated photobioreactors. This work has also improved the understanding of the biochemical mechanisms of harmful algal blooms and marine biodiversity monitoring. Among the challenges for research: moving to industrial production with low production costs, increasing the genetic diversity of algal strains, and developing integrated and energy-efficient bioprocesses, while establishing favorable regulatory frameworks for phytoplankton GMOs.

Jean Paul Cadoret : Algamafood, Chris Bowler : CNRS, ENS and Claire Hellio : UBO

1 - Scientific background:

Microalgae biotechnology has seen remarkable advances, driven by their applications across energy, food & feed, health, and environmental sectors. Microalgae are highly valued for their rapid and controlled growth, adaptability, and rich composition of bioactive compounds such as lipids, proteins, polysaccharides, pigments, and antioxidants.

Applications and Advances

• Bioenergy: Microalgae are at the forefront of research into biofuels, including biodiesel, bioethanol, and biohydrogen. Their high lipid content and CO₂ capture capability make them a promising alternative to fossil fuels. However, challenges in cost efficiency and process optimization continue to hinder large-scale industrialization.
• Food and Health: Algae are regarded as "superfoods," rich in proteins, vitamins, and omega-3 fatty acids. Innovations focus on incorporating them into human and animal diets. Bioactive compounds such as phycocyanins, fucoxanthin, and sulfated polysaccharides exhibit anti-inflammatory, antioxidant, and antiviral properties, with growing applications in cosmetics and medicine.
• Environmental Applications: Algae play a key role in bioremediation, including heavy metal absorption and CO₂ reduction. They are also used in wastewater treatment, enabling nutrient recovery and minimizing eutrophication.

2 - Main Contributions of the French Communities through ANR co-funding

These programs are state-of-the-art and innovative for several reasons. They combine cutting-edge approaches, advanced technologies, and goals that address both current and future global challenges. Here we provide an explanation of what makes them particularly forward-thinking:

Exploitation of Algae (e.g., ALGOMICS, ALGORAFFINERIE, POLYSALGUE, FLOTALG, ALGAdvance, DiaDomOil)

Microalgae are an underutilized natural resource that offer promising possibilities for industries such as agriculture, health, and energy. These programs focus on extracting complex biomolecules (polysaccharides, glycosides, etc.) from algae for various applications such as for production of biofuels, biodegradable materials, food, and medical treatments. Algae research is also key to mitigate climate change due to their photosynthetic metabolism and thus their ability to capture CO₂.

Adaptation to Environmental Changes (e.g., PhytAdapt, PhytoMET, SOLAB, DUNE, CARCLIM)
Climate change is a major challenge for biodiversity and agriculture, posing threats for both terrestrial and marine ecosystems. These innovative programs focus on how microalgae can adapt to extreme environmental conditions (e.g., heat and nutrient limitation).

Understanding how these organisms adapt to environmental stress is crucial for preserving and protecting ecosystem function in the face of increasingly unpredictable climate conditions.

Cutting-Edge Technologies for Agriculture and Industry (e.g., GenoSynTox, NEUROSPIROIMINE, BioTechAlg, DiaDomOil, TAD)

These programs integrate advanced technologies such as genomics, artificial intelligence, and bioengineering to optimize production and improve public health. For example, GenoSynTox explores the genetics of toxins, while NEUROSPIROIMINE uses innovative approaches to understand neurodegenerative diseases. BioTechAlg explores industrial applications of microalgae for high value compounds such as antibacterials, preservatives and nutraceuticals, while DiaDomOil has explored lipid biosynthesis in diatoms.

Genomics and Biomarker Research (e.g., GenoFonctDinoFI, France Génomique, BIOMARKS)

Genomics is an emerging field that is paving the way for a new era of precision medicine and environmental monitoring. Programs like France Génomique focus on identifying biomarkers to better understand diseases, improve personalized treatments, and address public health challenges. Together with BIOMARKS it has also enabled important advances in understanding marine ecosystems through analysis of Tara Oceans data.

Sustainable Production Systems (e.g., KEOPS 2, OCEAN-15, BIOCAREX)

Programs like KEOPS 2 and OCEAN-15 focus on sustainable solutions for industries and natural resource management. OCEAN-15 explores marine ecosystems, which play a crucial role in climate regulation and biodiversity. BIOCAREX emphasizes biological care and natural treatments, highlighting the need for a more sustainable approach to healthcare and health management.

Innovation in Natural Resource Management (e.g., ALGORAFFINERIE, SOLAB, Photo-Phyto)

The sustainable use of natural resources is a major future challenge. Programs like ALGORAFFINERIE aim to refine and use algae and other biomaterials for producing eco-friendly and sustainable products. Photo-Phyto explores the use of plant photosynthesis for new energy or ecological technologies.

Research on Complex Biological Processes (e.g., RHOMEO, PhytoMET, SynDia, GRAL)

These programs focus on studying complex biological processes at the molecular level. RHOMEO and SynDia explore how cells, genes, and proteins interact to create biological mechanisms that can be leveraged for medical, environmental, and industrial applications. PhytoMET has focused on capture and utilization of trace metals by microalgae. This research is essential for developing new therapies, optimizing biotechnology, and designing new materials, as well as for understanding the fundamentals of how life works.

Rapid and Evolving Responses to Global Challenges (e.g., Rapid Evol, OUTPACE, Facteur 4)

These projects focus on how biological systems, particularly species and ecosystems, can evolve and adapt quickly to changing conditions. Rapid Evol studies the rapid evolution of organisms to understand how biodiversity can be preserved in an ever-changing world. Facteur 4 looks at reducing ecological footprints by optimizing production and consumption systems—an essential step for a sustainable future.

Advanced Medical Applications (e.g., NEUROSPIROIMINE, GenoFonctDinoFI, PRIAM)

Future medical applications are being revolutionized by the use of advanced technologies such as genomics, gene editing (CRISPR), and synthetic biology. NEUROSPIROIMINE and PRIAM focus on serious diseases (neurodegenerative diseases, cancers, etc.) and explore innovative treatments that could transform how diseases are diagnosed and treated.

In summary: These programs are innovative and futuristic because they address major global issues such as climate change, health, sustainable use of natural resources, and optimization of food and industrial production. They use advanced technologies (genomics, bioengineering, artificial intelligence) and explore untapped or underutilized areas (such as algae and biotechnology), paving the way for solutions that could transform society in the coming decades.

3 – Scientific progress; cutting edge science

The programs represent cutting-edge scientific advancements in marine algae, biotechnology, and ecosystem characterization. Key breakthroughs include the application of CRISPR-Cas9 for precise genetic engineering of algae, enabling enhanced biofuel production and synthesis of high-value compounds. Genomic sequencing of species like diatoms and dinoflagellates has unveiled pathways for toxin production and adaptation mechanisms, critical for managing harmful algal blooms and understanding biochemical mechanisms. Advances in biosensors and DNA metabarcoding have allowed characterization and improved monitoring of marine biodiversity and ecosystem health. Innovations in bioremediation leverage algae to remove pollutants, while biorefineries extract multiple high-value products, from biofuels to nutraceuticals.

On the biomedical front, neuroactive compounds from microalgae show promise for treating neurodegenerative diseases, and antimicrobial peptides could help combat antibiotic-resistant pathogens. In environmental science, algae-driven carbon sequestration models and strategies for ecosystem resilience address climate change impacts, such as ocean acidification. Scalable technologies like AI-powered photobioreactors and offshore algae cultivation platforms enhance biomass production.

These programs bridge fundamental science and industrial applications, emphasizing interdisciplinary collaboration. They address global challenges in energy, healthcare, and environmental restoration, offering innovative solutions for sustainable development, particularly in vulnerable coastal communities.

Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities

The programs mentioned represent significant innovation for private enterprises, science policy, and citizens, particularly with a focus on coastal communities. Here's how these innovations impact each of these areas:

Innovation for Private Enterprises: New Markets and Economic Opportunities

• Biotechnology and Eco-friendly Products: Programs focused on algae, such as ALGOMICS, BIOCAREX, DiaDomOil and ALGORAFFINERIE, provide private enterprises with opportunities to develop and commercialize bio-based products. Microalgae, for example, can be used to create biofuels, biodegradable plastics, food ingredients, and pharmaceuticals. This could lead to new industries and jobs, especially in coastal regions where algae are abundant.
• Sustainable Practices and Resource Management: Programs like SOLAB, KEOPS 2, BIOMARKS, PhytADAPT and OCEAN-15 promote ecosystem characterization and sustainable resource management, which is crucial for industries such as fisheries, tourism, and agriculture. Coastal communities rely heavily on natural resources, and private enterprises can adopt these innovative practices to ensure long-term viability while reducing environmental impact. Companies that innovate with eco-friendly technologies can also access new markets and attract environmentally conscious consumers.
• Agricultural and Aquaculture Innovations: ALGAdvance, and GenoSynTox aim to improve agricultural and aquaculture productivity through genetic research and sustainable methods. Private enterprises involved in these sectors can utilize such innovations to enhance crop and seafood yields, improve resistance to environmental stresses, and develop new products, creating value while addressing food security issues.

Cost Efficiency and Risk Management

By integrating cutting-edge technologies in genetic research, bioengineering, and artificial intelligence (e.g., GenoSynTox, TAD), private enterprises can enhance operational efficiency, reduce costs, and minimize risks associated with climate change and environmental degradation. For instance, developing drought-resistant crops or more resilient marine life can help mitigate risks and improve supply chain stability for coastal industries.

Innovation for Science Policy

Informed Policy Making

• Data-Driven Decision Making: Programs like GenoFonctDinoFI, and BIOMARKS generate critical data on genomics, biodiversity, and ecosystems, which can inform science policy. Governments can use this data to make informed decisions about biodiversity conservation, ecosystem protection, and the regulation of industries impacting coastal communities. The innovation from these programs helps policymakers understand the full scope of environmental and health impacts, ensuring that policies are evidence-based and forward-thinking.
• Coastal Ecosystem Protection: Programs like OCEAN-15, DUNE, and CARCLIM focus on studying and protecting coastal ecosystems, which are highly vulnerable to climate change. Science policies can be shaped by the findings from these programs, leading to better coastal management and sustainable development practices. This is crucial for preserving ecosystems that are central to the livelihoods of coastal communities, such as fishing, tourism, and agriculture.
• Sustainability and Climate Action: Rapid Evol, Facteur 4, and SynDia focus on the adaptation of species and ecosystems to climate change. Science policy can be directed toward creating frameworks for integrating these innovative findings into environmental and climate change strategies. Policy innovation can also promote the development of new technologies for carbon capture, renewable energy, and waste management in coastal areas.

Public-Private Partnerships

These programs encourage collaboration between government agencies, research institutions, and private enterprises. By fostering public-private partnerships, science policy can ensure that innovations are translated into practical, scalable solutions for coastal communities, enhancing resilience to climate change and advancing sustainable economic development.

Innovation for Citizens with a Focus on Coastal Communities

Improved Livelihoods and Resilience

• Diversification of Income Sources: Coastal communities often rely heavily on traditional industries such as fishing, agriculture, and tourism, which are vulnerable to climate change and overexploitation. Innovations from programs like ALGORAFFINERIE, SOLAB, and BIOCAREX provide new opportunities for coastal residents to diversify their income sources. For example, the cultivation and commercialization of algae-based products could provide new local industries and employment, reducing dependence on traditional sectors that may be declining due to environmental challenges.
• Climate Adaptation and Coastal Protection: Programs like OCEAN-15, DUNE, and CARCLIM are focused on understanding and mitigating the impacts of climate change on coastal ecosystems. This research can directly benefit coastal communities by improving flood defenses, restoring damaged ecosystems like mangroves and coral reefs, and developing better disaster preparedness and response strategies. This enhances resilience and reduces vulnerability to natural disasters such as storms, rising sea levels, and coastal erosion.
• Health Benefits and Food Security: Programs like DiaDomOil and BioTechAlg aim to improve production practices for food and high value compounds. By developing strategies to develop more resilient crops for agriculture and sustainable aquaculture practices, these innovations can help society maintain food supplies despite changing environmental conditions. Furthermore, bioactive compounds derived from microalgae can provide new opportunities for improving public health and nutrition.

Public Awareness and Empowerment

• Citizen Engagement in Environmental Stewardship: By focusing on coastal ecosystems, these programs raise awareness about the importance of environmental conservation. Coastal communities can become more involved in protecting their local environment, whether through sustainable fishing practices or eco-tourism. This empowerment allows citizens to play an active role in addressing climate change and conserving natural resources.
• Education and Capacity Building: Programs like France Génomique and GenoSynTox contribute to the education and capacity building of local populations, providing them with knowledge about the latest scientific developments. This knowledge can be used to make informed decisions about resource management, environmental protection, and health care, enabling coastal communities to thrive sustainably.

Social Innovation

Creating Social Enterprises: Innovations from these programs offer opportunities for social entrepreneurship. Coastal communities can create local businesses focused on sustainable practices, such as algae-based products, eco-tourism, or sustainable aquaculture. These businesses can create jobs, stimulate the local economy, and provide long-term economic stability while preserving the environment.

The innovations presented in these programs are transformative for private enterprises, science policy, and citizens, particularly in coastal communities. For private enterprises, they offer new business opportunities, greater sustainability, and risk management strategies. For science policy, they provide valuable data and insights to inform better governance, particularly in the areas of coastal ecosystem protection, climate change adaptation, and sustainable resource management. For citizens, these innovations help create more resilient, diversified, and empowered coastal communities, enhancing their ability to adapt to environmental challenges while improving their quality of life. By addressing both local and global challenges, these programs contribute to a more sustainable and equitable future for coastal communities around the world. Among the programs listed, several create strong links or contributions to human societies in various ways, particularly in economic, cultural, and adaptation contexts, as well as in the evolution of practices and uses.

Below is an overview of how these programs contribute to different aspects of human societies:

1. ALGOMICS, BIOCAREX, ALGORAFFINERIE, POLYSALGUE, FLOTALG, ALGAdvance (Algae-Based Innovations)

Economic Contribution:

• Algae-Based Products: These programs explore the use of algae for diverse products such as biofuels, biodegradable plastics, food additives, and pharmaceuticals. The economic impact is significant as it opens new markets and revenue streams. By providing alternative sources of raw materials, these programs help diversify local economies, especially in coastal areas where algae can be abundant.
• Job Creation: The development of algae-based industries creates new job opportunities in areas like cultivation, processing, research, and product development, benefiting local economies, especially in coastal regions that are economically dependent on natural resources.
• Sustainable Industry: Algae-based products are eco-friendly, reducing the need for fossil fuels and petrochemical products. This contributes to economic resilience by promoting a green economy, creating long-term, sustainable jobs, and reducing environmental degradation.

Cultural Contribution:

• Traditional Knowledge and Innovation: In coastal communities, algae have been used traditionally for food, medicine, and other purposes. These programs bridge traditional practices with modern technology, helping to preserve cultural heritage while introducing new, innovative applications. This blend of tradition and innovation helps maintain cultural identity while fostering economic and environmental sustainability.

2. PhytAdapt, DUNE, SOLAB, CARCLIM, BIOMARKS (Adaptation to Environmental Changes)

Adaptation and Evolution of Uses:

• Climate Resilience: These programs focus on how microalgae and ecosystems in general adapt to climate change. They explore the genetic mechanisms behind stress tolerance and help improve understanding of how organisms evolve and how ecosystems adapt to change.
• Coastal Protection: Programs like DUNE and CARCLIM contribute to the protection of vulnerable coastal ecosystems (such as dunes and wetlands) that provide natural protection against flooding, storms, and erosion. The sustainable management of these ecosystems plays a crucial role in protecting human settlements and preserving local cultural and economic practices.

Economic Contribution:

Marine ecosystem management. Improved understanding of marine ecosystems can help identify areas that deserve special protection, that can benefit both natural ecosystems and enhance sustainable management of fisheries.

• Eco-Tourism: The conservation of coastal ecosystems can contribute to the growth of eco-tourism, a significant economic activity in many coastal areas. The restoration of habitats and sustainable management of resources also enhances the attractiveness of these regions as tourism destinations, benefiting local businesses.

3. OCEAN-15, BIOCAREX, KEOPS 2, BIOMARKS (Marine and Coastal Ecosystem Protection)

Cultural Contribution:

• Cultural Significance of Coastal Ecosystems: Coastal ecosystems such as mangroves, coral reefs, and seagrasses are often of cultural importance to indigenous and local communities. Programs like OCEAN-15 and KEOPS 2 aim to protect these ecosystems, ensuring that future generations can continue to access and benefit from them. This is especially important for communities whose cultural practices are deeply tied to marine and coastal resources (e.g., fishing, coastal rituals).

Economic Contribution:

• Sustainable Fisheries: By protecting marine ecosystems, these programs help preserve sustainable fisheries, which are crucial for the livelihoods of many coastal communities. BIOCAREX, in particular, focuses on bio-based solutions, including those derived from marine resources, contributing to sustainable fishing practices and the development of marine-based products like pharmaceuticals, cosmetics, and food.
• Ecosystem Services: Coastal ecosystems provide essential services such as carbon sequestration, storm surge protection, and water purification. By investing in their protection, these programs contribute to reducing the economic costs of climate change, such as damage from floods and storms, which disproportionately affect coastal communities.

4. France Génomique, GenoSynTox, GenoFonctDinoFI (Genomics and Biotechnology)

Cultural Contribution:

• Public Health and Knowledge: These programs contribute to a better understanding of genomics, which can be used to improve human and environmental health. By understanding the genetic bases of diseases and environmental stress, these programs can lead to more effective treatments and interventions for health issues that disproportionately affect coastal communities (e.g., diseases caused by environmental factors or those linked to marine organisms).
• Cultural Heritage Preservation: Genomics can also play a role in preserving the genetic diversity of traditional crops, livestock, and marine organisms that are central to local cultural practices. This helps safeguard the genetic resources that local populations rely on for food, medicine, and cultural rituals.

Economic Contribution:

Biotechnology Innovation: The biotech advancements fostered by these programs have the potential to create new products and industries, such as improved crops, disease-resistant fish, and biopharmaceuticals, opening up new markets and economic growth opportunities for coastal and rural regions.

5. ALGALGLYCO, SynDia, MetaboLIGHT (Health and Biotechnology)

Economic Contribution:

• Health and Wellness Markets: These programs focus on using microalgal compounds for health applications, such as functional foods, nutraceuticals, and supplements. The development of these products not only contributes to human health but also opens up new markets, especially in coastal areas where traditional uses of plants and algae could be adapted to modern wellness trends.

Cultural Contribution:

Traditional Knowledge in Modern Contexts: Many coastal communities have long histories of using local plants and marine organisms for medicinal purposes. These programs integrate traditional knowledge with modern biotechnological research, preserving and valorizing local culture while promoting the development of modern health products.

6. PhytAdapt, RHOMEO, (Agricultural and Human Health Adaptation)

Adaptation and Evolution of Uses:

• Health and Environmental Synergy: Programs like PhytAdapt that focus on ecosystem resilience also have direct links to human health by ensuring the continued availability of food in the face of environmental stress. Similarly, RHOMEO focuses on the impacts of environmental changes on human health, allowing for the development of adaptive practices that ensure human survival and well-being in changing climates.

Cultural Contribution:

• Knowledge Sharing: By integrating scientific knowledge with local traditional farming techniques, these programs can foster a culture of knowledge-sharing between the scientific community and local populations. This helps evolve agricultural practices while preserving local cultural heritage and practices.

Conclusion for social innovation:

Many of the projects listed above create significant links to human societies by contributing to economic growth, cultural preservation, and adaptation. They foster sustainable practices that enhance resilience to climate change and improve human well-being, particularly in coastal communities. Whether by creating new industries, preserving cultural traditions, or offering solutions for environmental adaptation, these programs offer tangible benefits for local populations, allowing them to evolve and thrive in an ever-changing world.

Methodological breakthroughs

Many of the programs listed involve methodological breakthroughs in various scientific fields, particularly in biotechnology, genomics, sustainable resource management, and environmental conservation. These breakthroughs often combine new technologies, novel approaches, and interdisciplinary strategies to address complex problems. Below are some of the key methodological innovations from these programs:

• Biotechnology and Algae-Based Products (e.g., ALGOMICS, BIOCAREX, DiaDomOil, ALGORAFFINERIE, POLYSALGUE, FLOTALG, ALGAdvance)
• Algal Biotechnology: One of the main breakthroughs in these programs is the development of more efficient methods to cultivate and process algae for various uses, such as biofuels, biodegradable plastics, and food additives. Methods to optimize algal growth and increase biomass yield under specific environmental conditions are key innovations.
• Metabolic Engineering: Using advanced metabolic engineering techniques, scientists are modifying algae to produce valuable compounds like oils, proteins, and polysaccharides more efficiently. This can revolutionize industries related to biofuels, carbon capture, and food production.
• Green Biorefinery Techniques: ALGORAFFINERIE develops new biorefining processes that extract multiple high-value products from algae. These processes use environmentally friendly methods to ensure sustainability and efficiency, which is crucial for scaling up commercial algae production.

Breakthroughs in Sustainability:

• Carbon Sequestration via Algae: The development of large-scale algae cultivation for carbon sequestration is another breakthrough. Algae capture carbon dioxide during photosynthesis, and some of these programs focus on optimizing this process for large-scale applications, which has the potential to combat climate change.

Genomics (e.g., GenoSynTox, GenoFonctDinoFI):

• These programs utilize big data analytics to understand the genetic bases of diseases, enabling large-scale, population-based studies that could lead to breakthroughs in disease prediction, prevention, and treatment.
• GenoSynTox explores genetic responses to toxins, offering breakthroughs in understanding how different individuals or populations might react to environmental toxins. This can lead to improved environmental monitoring and safety standards.

Ecological Modeling and Monitoring (e.g., PHYTADAPT, OCEAN-15, DUNE, CARCLIM, KEOPS 2):

• Ecosystem Simulation and Prediction: Programs like PHYTADAPT and OCEAN-15 use sophisticated modeling tools to predict how marine ecosystems will respond to climate change, pollution, and human intervention. These models integrate large amounts of environmental, biological, and climatic data, helping to develop more effective conservation strategies.
• Remote Sensing and Monitoring: Advances in satellite and drone-based technologies are allowing for more efficient and accurate monitoring of coastal ecosystems. Programs like DUNE and CARCLIM use remote sensing tools to track changes in coastal landscapes, providing real-time data that can guide conservation efforts and policy.
• Restoration Ecology: These programs develop new methods for restoring degraded coastal ecosystems (e.g., mangroves, coral reefs) using a combination of active restoration and assisted natural regeneration. The innovative use of genetic tools to enhance the resilience of coastal species is also a key methodological breakthrough.

Gene Editing (e.g., PhytoMet,, RHOMEO):

• CRISPR and Other Gene Editing Techniques: These programs employ gene-editing technologies like CRISPR/Cas9 to better understand microalgal gene function. By directly modifying algal genomes, scientists can introduce beneficial traits for biotechnological applications.

Adaptation Mechanisms in Species and Ecosystems (e.g., CARCLIM, SOLAB, KEOPS 2, PhytAdapt):

• Evolutionary Biology and Adaptation: Programs focus on studying how species evolve in response to environmental pressures. The use of evolutionary genomics helps predict how populations will adapt to changing conditions and provides insights into how to assist this process through conservation strategies (e.g., assisted migration or genetic rescue).
• Climate Change Adaptation: These programs develop methodologies to assess and facilitate the adaptation of ecosystems and species to climate change. The integration of genetic, ecological, and climatic data to predict adaptation pathways is an innovative approach in environmental science.

Ecological Restoration and Management:

• Hybrid Ecosystem Restoration: Using a combination of restoration ecology and genetic tools, these programs work on improving ecosystems' ability to adapt to climate change, enhancing biodiversity through active interventions. This includes introducing species that may be more resilient or modifying ecosystems to improve their resistance to environmental stressors.

Sustainable Resource Management and Circular Economy (e.g., ALGAdvance, BioTechAlg, Facteur 4)

• Waste-to-Value Innovations: Programs like BioTechAlg focus on converting waste products (e.g., algae biomass, agricultural waste) into valuable resources (e.g., preservatives, antioxidants). This approach not only addresses waste management issues but also contributes to sustainable production practices in industries.
• Resource Efficiency: Programs that focus on improving the efficiency of resource use in sectors such as energy, agriculture, and materials manufacturing contribute to the development of more circular and sustainable economic models. The innovative use of biological processes to create new products from waste could lead to breakthroughs in resource efficiency and sustainability.

New Data Analytics (e.g., BIOMARKS, TAD,)

• Predictive Modeling for Health and Ecosystems: BIOMARKS employ computational approaches to analyze vast amounts of data related to marine ecosystems. These tools help predict trends and make data-driven decisions about resource management, and help to characterize marine ecosystem biodiversity.

Conclusion for Methodological breakthroughs:

These programs introduce several methodological breakthroughs across a range of disciplines, including genomics, biotechnology, environmental science, and data analytics. Key innovations include:

• Advanced genetic engineering techniques, such as CRISPR for gene editing.
• New approaches in ecosystem monitoring, using remote sensing and AI to better understand and protect ecosystems.
• Biotechnology innovations, such as algae-based products and waste-to-value solutions, promoting sustainability and green industries.

These breakthroughs not only push the boundaries of current scientific knowledge but also offer practical solutions to urgent global challenges, making them crucial for future economic, cultural, and environmental progress.

4 - Research perspectives

Identifying barriers and gaps in research and innovation across these programs is crucial for understanding the challenges that must be overcome to fully unlock their potential and accelerate their development. Below is an overview of the scientific aspects and innovation-related aspects, highlighting areas where progress can be made and how these can be addressed to increase the Technology Readiness Level (TRL).

Scientific Barriers and Gaps

A. Biotechnology and Algae-Based Products

Scientific Barriers:

• Scalability Issues: One major challenge in algae-based biotechnology is the scalability of production systems. Although lab-scale success is achieved, scaling up algae cultivation and bio-refinement for industrial applications faces challenges in cost, efficiency, and resource optimization.
• Genetic Diversity and Strain Development: There is a need for broader genetic diversity in algal strains to improve yields, resistance to diseases, and tolerance to environmental stressors. Research into identifying and developing novel algal strains with superior traits is still underdeveloped.
• Optimization of Bioprocessing: While many algae-based products have been identified, optimizing the bioprocessing methods for the extraction and transformation of biomass into usable products (e.g., biofuels, pharmaceuticals, and food) is still in the early stages.

Gaps:

• Integration of Systems: A gap exists in integrating algae cultivation with downstream processing (harvesting, refining) in a continuous, integrated system that minimizes energy and resource consumption.
• Biorefinery Techniques: There is still a lack of efficient biorefinery processes that extract multiple value-added products from algae simultaneously, rather than focusing on single-product output.

B. Genomics and gene editing

Scientific Barriers:

• Complexity of Genomic Data: Handling, interpreting, and correlating vast amounts of genomic data with clinical outcomes remain a significant challenge. Despite advances in sequencing technologies, integrating genetic, environmental, and lifestyle data into predictive models for personalized medicine is still rudimentary.
• Heterogeneity in Populations: There is a gap in the study of genomic diversity across different human populations, especially among underrepresented groups. Most genomic research has focused on specific populations, leaving a gap in global representation.

Gaps:

• Data Privacy and Security: As genomic data becomes more integrated with healthcare, privacy and security concerns increase. There is a need for better data protection and governance frameworks.
• Clinical Translation: Many genomic findings, although promising in research, fail to make the leap to clinical applications. More work is needed to translate genomic discoveries into actionable therapies, diagnostic tools, and personalized treatments.
• Genetic Adaptation to Stressors: While CRISPR and gene editing offer great potential, identifying the right genes to target is still an evolving field. Understanding the complex genetic networks involved remains a scientific challenge.

C. Marine and Coastal Ecosystem Protection

Scientific Barriers:

• Climate Change Impact Predictions: While models for ecosystem response to climate change are improving, predicting complex interactions between climate stressors, species, and ecosystems still remains a challenge.
• Data Gaps in Biodiversity: In many coastal areas, there are significant data gaps regarding the biodiversity of marine species and the full range of ecosystem services they provide. A comprehensive understanding of marine and coastal biodiversity is needed for effective protection and restoration strategies.

Gaps:

• Integrated Monitoring Systems: There is a lack of unified monitoring systems that integrate data from multiple sensors (e.g., satellites, drones, in-situ measurements) for real-time ecosystem assessment.
• Ecosystem-Based Management (EBM): While EBM approaches are gaining traction, there are still many gaps in the practical implementation of these models. More research is needed to fine-tune ecosystem-based strategies for effective, region-specific management of coastal zones.

Innovation Barriers and Gaps (Increasing TRL)

A. Scaling and Commercialization of Algal Products

Barriers:

• TRL 3-5 (Prototype/Pre-commercial): Many algae-based innovations are still in early-stage development, with limited transition to commercial-scale production. The cost-effectiveness and industrial scalability of algae-based technologies, particularly biofuels and biodegradable plastics, are key barriers.
• Public Acceptance and Market Development: The market for algae-based products (like food and materials) is still niche, and consumer acceptance is a barrier. Educating consumers and establishing a reliable market demand are crucial for innovation to scale. Use of genetically-modified algae is likely to pose additional concerns for the public, at least in Europe.

Gaps:

• Business Models: Innovative business models that bridge the gap between research and commercial adoption of algae-based technologies are needed. This includes creating value chains for algae that connect researchers, producers, and consumers in a way that makes economic sense.

B. Translation of Genomic Research to Clinical Use

Barriers:

• TRL 4-6 (Demonstration/Prototype Development): While genomic research is advancing, translating it into tangible clinical applications, such as personalized medicine, is still challenging. Moving from research findings to scalable, real-world medical solutions often requires more collaboration between academia, industry, and healthcare providers.

Gaps:

• Interdisciplinary Collaboration: There's a gap in collaboration between genomic researchers, medical professionals, and tech companies to develop effective diagnostic tools and therapies that leverage genomic data. Increased integration between these sectors is essential for TRL advancement.
• Regulatory Hurdles: Regulatory frameworks around the use of genomic data and gene therapies are still evolving. Clearer regulations and faster approval processes are needed to ensure that innovations reach the market faster.

C. Ecosystem Monitoring and Restoration at Scale

Barriers:

• TRL 3-5 (Prototype/Pre-commercial): Marine and coastal ecosystem restoration and protection efforts are still in early stages. Developing cost-effective, scalable restoration techniques and efficient monitoring systems remains a significant hurdle.
• Integration of Technologies: The integration of various technological systems for ecosystem monitoring (e.g., remote sensing, drones, AI analytics) is not yet seamless, limiting the ability to assess ecosystems effectively at large scales.

Gaps:

• Scalable Restoration Techniques: There is a gap in developing large-scale, cost-effective restoration techniques, such as coral reef restoration and mangrove regeneration, that can be applied worldwide.
• Advanced Sensor Networks: There is also a need for more advanced and affordable sensor networks for continuous monitoring of ecosystems, which can support real-time decision-making for conservation and restoration projects.

D. Climate-Resilient Crop Development and Adoption

Barriers:

• TRL 3-6 (Prototype/Commercial Development): While there have been significant advances in genetically modified crops, scaling these innovations to meet the demands of global agriculture remains a challenge. Regulatory approval and acceptance in various markets remain significant barriers to scaling climate-resilient crops.

Gaps:

• Integration with Farming Systems: The integration of climate-resilient crops into existing agricultural systems, especially in developing countries, is still a challenge. Tailoring crop traits to suit specific regions and farming practices is essential for widespread adoption.
• Pest and Disease Resistance: Developing crops that are resistant to both environmental stress and pests/diseases remains an ongoing challenge, particularly under changing climatic conditions.

Future Perspectives

• Collaboration between Public and Private Sectors: Bridging the gap between research and commercialization through partnerships will be key to advancing these programs. Increased industry involvement can help accelerate the transition of innovations from the laboratory to the market.
• Data and Computational Tools: Enhancing data-sharing platforms and developing more advanced computational models (e.g., AI for predictive modeling, genomic data analytics) can improve the rate at which new insights are translated into tangible products and solutions.
• Regulatory and Policy Development: Streamlining regulatory processes to accommodate emerging technologies, such as genetic modifications, algae-based products, and climate-adaptive crops, will be essential for increasing the TRL of these innovations.

By addressing these scientific barriers and gaps, and focusing on increasing the TRL through targeted innovation strategies, these programs can make significant strides toward sustainable solutions that benefit both human societies and the environment.

Challenges and Opportunities

• Reducing production costs (cultivation, harvesting, and extraction).
• Enhancing strain performance using genetic engineering for higher biomass yields and stress resilience.
• Developing sustainable and circular bioprocesses.

Advances in synthetic biology and bioengineering are paving the way for the use of genetically modified algae strains grown in closed reactors and optimized for specific outputs. Additionally, technologies like automated photobioreactors and artificial intelligence are improving monitoring and production efficiency.

The future of the microalgae industry is promising, with significant potential to address global challenges in sustainability, food security, and energy. As a versatile resource, microalgae can produce biofuels, bioplastics, and high-value compounds like omega-3 fatty acids and antioxidants. Advances in biotechnology and cultivation systems are improving cost-efficiency and scalability, opening opportunities in pharmaceuticals, nutraceuticals, and carbon capture. Moreover, the growing demand for eco-friendly and plant-based solutions positions microalgae as key players in transitioning to a circular bioeconomy. Continued research, policy support, and investment are pivotal for unlocking the full potential.

Microbial ecosystems

The study of microbial interactions – the ecology of viruses and their role in the microbial loop – is crucial for understanding biogeochemical cycles and antimicrobial activities. Research supported by the ANR has led to major advances in the understanding of biofilms, surface chemistry, electrochemistry, marine biotechnology, marine ecology, and sensor engineering.:. As part of these researches, projects are being conducted to develop natural antifoulings (enzymes, peptides, exopolymers) from marine organisms (bacteria, sponges, algae). France was a pioneer in banning antifouling paints in 1982, following French work showing the harmful effect of paints containing organotin compounds (TBT) on the reproduction and malformation of oysters. Within biotechnology and synthetic biology, new researches are emerging in fields such as the use of marine molecules, enzymes, or genetic tools for biotechnological and medical applications for marine microbiology.

Scientific background

In addition to Tara projects, other researchers are studying the ecology of viruses, their interactions with phytoplankton and their role in the microbial loop. Microbial activities control the major biochemical cycles (complementing the form of biogeochemical cycle). Specific antifouling activities are addressed for bioactive products and anti-microbial activities. As fouling is firstly due to colonisation by bacterial films, research focuses on developing efficient anti-fouling solutions to apply on ship hulls to prevent marine organisms from attaching, which slows down the vessel and increases fuel consumption.

Impacts on public policies and socio-economical innovation

France was the first country to ban the use of-fouling paints in 1982, following our research showing the harmful effect of paints containing organic tin salts (TBT) on the reproduction and malformation of oysters. The International Maritime Organisation (IMO) then adopted the International Convention on the Control of Harmful Anti-Fouling Systems on ships (AFS Convention) on 5 October 2001, which came into force on 17 September 2008. This convention prohibits the use of organotin compounds, such as tributyltin (TBT). The global industry for marine antifouling paints, designed to protect ships’ hulls against marine organisms, represented an estimated turnover of $1.08 US in 2024. Current projects are tackling the challenge of developing innovative sensors for bio-fouling.

Main outcomes of the ANR-funded projects

Numerous projects investigated microbial interactions (viruses, parasites and symbiosis) and how microbes shape or respond to marine ecosystems. Research has been carried out on viruses and their microbial interactions with evolutionary traits of eukaryotic DNA viruses (mirusvirus). Focusing on the relationship between phytoplankton and virus demonstrated resistance mechanisms in phytoplankton-virus dynamics and biogeochemical impacts of RNA viruses in diatoms. Viral contamination in shellfish could be caused by hydrometeorological events. Several projects also explored microbial diversity in undersampled ecosystems, as previously uncharacterised or uncultivated microorganisms were only present. Studying biogeochemical cycles contributes to better understanding carbon, methane, halomethane and nutrient cycling in marine and coastal environments. Other projects have screened antimicrobials activities for bio-preservation of marine organisms (bacteria, fungi and algae) for bioactive molecules, including antimicrobial peptides (AMPs), with potential applications in food safety and health.

The core scientific content of anti-fouling projects focuses on marine microbiology with studies on: 1) biofilms to understand how microorganisms colonise submerged surfaces (bacteria, algae, spores) and how biofilms initiate; 2) surface chemistry and material by designing new materials (polymers and nanostructures) with anti-adhesive properties; 3) electrochemistry with adequate smart coating using piezoelectric, photoactive and amphiphilic materials that respond dynamically to stimuli, e.g. vibration, light and seawater ions; 4) Marine biotechnology with exploration of natural antifoulants (e.g. enzymes, peptides and exopolymers) from marine organisms (bacteria, sponges and algae); 5) marine ecology with fouling communities through studies on ecological succession on surfaces and how biofouling alters material performance, biodiversity and sensor data quality; 6) sensor engineering integration of anti-fouling strategies directly into marine sensors to ensure longterm deployment and data reliability.

By developing synthetic microbial ecology, projects are building and modelling frameworks to simulate evolutionary and ecological scenarios and starting to integrate genomics, physiology, and modelling to build predictive ecological models and even design synthetic communities.

Conclusion and research perspectives 

Biotechnology and synthetic biology are key future activities with emerging fields using marine molecules, enzymes and genetic tools for applied biotech and medical applications for microbiological contributions.

CORAL REEF research

Coral reefs are threatened by global warming, which, with an increase of only 1°C above normal summer temperatures, causes massive bleaching and increased coral mortality.39 ANR-supported projects have led to significant advances in the understanding and management of these ecosystems, particularly on the degradation of coral habitats; the impacts of El Niño on reef ecosystems; the development of genetic connectivity models for fish populations; and restoration techniques, such as larval rearing and coral micro-fragmentation. The projects have also highlighted the importance of genetic diversity and microbial communities for reef health, with the identification of strains resilient to warming waters. Research perspectives include the interdisciplinary integration of genomics, ecology, climate modeling, and social sciences, as well as international collaboration to strengthen coral research in degraded habitats.

Serge Planes: CNRS-EPHE-UPVD, Perpignan

1- Scientific background

The increase in global mean surface temperature (GMST), which reached 0.87°C in 2006–2015 relative to 1850–1900, has increased the frequency and magnitude of impacts, strengthening evidence of how an increase in GMST of 1.5°C or more could impact natural and human systems (1.5°C versus 2°C). Global warming (i.e., heat stress; Hoegh-Guldberg, 1999; Baker et al., 2008; Spalding and Brown, 2015; Hughes et al., 2017a) has emerged as the greatest threat to coral reefs, with temperatures of just 1°C above the long-term summer maximum for an area (reference period 1985–1993) over periods of 4–6 weeks being sufficient to cause mass coral bleaching (loss of the algal symbionts) and subsequent mortality. With the global warming observed to date, a large proportion of coral reefs have experienced large-scale mortalities that have led to a sharp reduction of coral populations. Predictions of consecutive bleaching events (Hoegh-Guldberg, 1999) became reality in the summers of 2016–2017 (e.g., Hughes et al., 2017a), as did projections of declining coral abundance. Therefore, a world with 1.5° to 2.0°C above pre-industrial levels will lead to major mortality of corals and disappearance of some coral reefs (Donner et al., 2005; Hoegh-Guldberg et al., 2014; Schleussner et al., 2016; van Hooidonk et al., 2016; Frieler et al., 2017; Hughes et al., 2017b).

In such a context of coral reef decline, coral reef science has rapidly evolved in the last decade, spurred by novel molecular techniques, advanced monitoring technologies, and innovative restoration strategies. These developments are critical for understanding and mitigating the impacts of climate change, ocean acidification, and local anthropogenic pressures on coral ecosystems. We can identify key areas that have shown change in paradigm linked to the declining context of coral reef.

Climate Change, Stressors, and Coral Resilience

Recent high-resolution studies confirm that rising sea temperatures and ocean acidification are primary drivers of coral bleaching and mortality. Satellite remote sensing, coupled with in situ measurements, now allows researchers to monitor thermal anomalies with unprecedented accuracy. For example, Hughes et al. (2018) documented that repeated bleaching events, even when severe, can sometimes be followed by partial recovery in resilient coral populations. Similarly, Guest et al. (2019) demonstrated that local environmental factors—such as hydrodynamics and shading—play crucial roles in modulating bleaching responses. Advances in molecular biology have deepened our understanding of coral stress responses. Genome-wide studies have revealed that some coral populations harbor genetic variants and epigenetic modifications that enhance their tolerance to heat (van Oppen et al., 2017; Bay et al., 2020). Metagenomic analyses show that corals can alter their symbiotic associations with dinoflagellates (Symbiodiniaceae) in response to stress. Studies by Rosado et al. (2019) and LaJeunesse et al. (2018) highlight that a shift toward thermotolerant symbiont clades correlates with enhanced resilience.

Technological Innovations and Enhanced Monitoring

Technological progress has revolutionized reef monitoring with the deployment of autonomous underwater vehicles, drones, and high-resolution satellites now enables continuous mapping of reef structure, water quality, and bleaching events (Donner et al., 2020; Mumby et al., 2020). Machine learning applied to these datasets improves prediction accuracy and informs adaptive management strategies. Distributed sensor networks measuring key environmental parameters (temperature, pH, salinity) allow for real-time monitoring. These systems have been pivotal in linking episodic stress events to coral responses, supporting adaptive management (Perry et al., 2019).

Advances in Coral Restoration Techniques

Restoration research has evolved from traditional coral gardening to sophisticated approaches that address both ecological and genetic dimensions. Techniques such as larval rearing and micro-fragmentation have shown promising results. Lirman et al. (2018) demonstrated that micro-fragmented corals can rapidly regenerate, significantly accelerating reef recovery. French research led by Mills and colleagues has further refined these techniques to maximize genetic diversity and resilience. Field experiments have tested the transfer of resilient coral genotypes to more vulnerable reefs. Assisted gene flow, as detailed by van Oppen et al. (2017) and supported by French investigations (e.g., Mills et al., 2019), shows promise in boosting the adaptive capacity of coral populations. Recent studies are exploring the manipulation of coral-associated microbial communities to enhance health and reduce bleaching. Work by Peixoto et al. (2021) and contributions from French scientists such as Sabourault et al. (2016) underscore the potential of “probiotic” treatments in improving coral resilience.

Integrative and Socio-Ecological Approaches

Recent coral reef studies increasingly integrate natural science with socio-economic perspectives. Recognizing that coral reefs provide critical ecosystem services—from coastal protection and food security to cultural heritage—researchers have begun incorporating social science methods to assess human dependencies on reef ecosystems. Anthony et al. (2019) and French experts like Lecchini et al. (2010) have illustrated how local management practices and traditional ecological knowledge enhance reef resilience. The coupling of high-resolution environmental data with socio-economic indicators has led to the development of decision-support tools. These tools are vital for designing adaptive management strategies that balance conservation with the livelihoods of coastal communities (Mumby et al., 2020; Perry et al., 2019). Contributions from French institutions such as the MSH-P and CRIOBE have been instrumental in this integrative approach.

The next phase of coral reef research focuses on multi-stressor experiments that integrate thermal, chemical, and biological challenges. Integrated models combining genomics, remote sensing, and socio-economic data are expected to yield more accurate predictions of reef trajectories under future climate scenarios (Fuller et al., 2020; Donner et al., 2020).

2 - Main contributions of the French communities through ANR co-funding

Overall, over that last decade coral reef science has moved beyond purely ecological descriptions to a systems-level understanding that includes genomics, environmental chemistry, modeling, and socio-economic analysis. Yet, knowledge gaps remain—particularly regarding multi-stressor impacts, transgenerational adaptation, and large-scale ecological tipping points. The projects funded by the French National Research Agency (ANR) collectively have addressed some of these gaps through cutting-edge research, cross-disciplinary collaborations, and innovative field and laboratory approaches.

In this section we focus on the ANR-(co)funded and PIA funded projects that illustrate France’s contributions to coral reef and marine biodiversity research. They have advanced our understanding of reef ecology, climate impacts, and socio-ecological dynamics, each featuring both scientific progress and innovation for stakeholders.

2.1 - Scientific Progress: Cutting-Edge Science

Recent French ANR-funded projects have collectively transformed our understanding of coral reef dynamics by integrating advanced field studies, innovative molecular techniques, and sophisticated modeling approaches. For instance, the Coral Reefs project (ANR-06-JCJC-0012), coordinated by David Lecchini at IRD, provided early and crucial insights into how habitat degradation—marked by a shift from coral-dominated to algal-dominated states—impacts the recruitment success of reef organisms such as fish, mollusks, and crustaceans. This project demonstrated that as coral cover declines, critical sensory cues used by larvae for habitat selection become altered, thereby reducing larval settlement and survival ( Lecchini et al, 2010; Dufour et al, 2010). Detailed laboratory and in situ experiments, including chemical and acoustic analyses, revealed that disrupted reef structures can compromise the complex behavioral and physiological processes that underpin successful recruitment, setting the stage for cascading effects on reef biodiversity.

Building on this foundation, the ELPASO project (ANR-10-BLAN-0608), under the coordination of Pascale Braconnot, advanced our understanding of large-scale climatic phenomena by reconstructing historical ENSO variability and linking these oscillations to shifts in marine productivity, thereby informing predictive models of reef ecosystem responses (Braconnot et al,2012). In parallel, the IM-MODEL@CORALFISH project (ANR-10-BLAN-1726) led by Serge Planes, developed novel maximum-likelihood models that capture the genetic connectivity and evolutionary history of reef fish populations, highlighting the importance of historical isolation and migration patterns in shaping contemporary reef biodiversity (Delrieu-Trotin et al, 2019).
Further exploring the resilience of reef ecosystems, the LIVE AND LET DIE project (ANR-11-JSV7-0012), coordinated by Suzanne Mills, provided critical insights into how multiple stressors—ranging from thermal anomalies to overfishing—alter reef community structures and drive adaptive physiological responses in coral reef organisms, emphasizing the role of early life-history stages in maintaining ecosystem function (Mills et al, 2019). Complementing these ecological and genetic approaches, the inSIDE project (ANR-12-JSV7-0009), coordinated by Cécile Sabourault, delved into the molecular interplay between cnidarians and their dinoflagellate symbionts, unveiling key proteins and metabolic mediators that govern symbiotic stability and the onset of bleaching, thereby offering potential targets for future intervention strategies (Sabourault et al, 2016).

Meanwhile, the BIOCARRA project (ANR-13-ISV7-0002), managed by Claude Payri, focused on the biodiversity and biogeography of coralline algae—essential architects of reef structure—by integrating molecular phylogenetics with advanced histological analyses to resolve longstanding taxonomic ambiguities and to map the distribution of these critical organisms across the Indo-Pacific (Payri et al, 2019). Recognizing the importance of larval dispersal in sustaining reef populations, the Stay or Go project (ANR-14-CE02-0005), coordinated by Suzanne Mills, examined the interplay between parental traits and environmental stressors, such as thermal anomalies and anthropogenic noise, and how they influence larval behavior and dispersal capacity. Research from Stay or Go showed that factors such as maternal size and the condition of parental habitats critically determine the swimming performance and subsequent recruitment success of larvae (Mills et al, 2018). The project’s innovative use of transgenerational experiments provided evidence that under stressful conditions, parental effects can induce phenotypic plasticity in offspring, which in turn affects their ability to navigate and settle in optimal reef habitats.

Addressing the imminent threat of ocean acidification, the CARiOCA project (ANR-15-CE02-0006) utilized natural CO₂ seeps as analogues to study coral acclimatization, demonstrating that certain coral species can undergo physiological adjustments that enable survival under chronically low pH conditions, thereby providing hope for reef persistence in a high-CO₂ future (Rodolfo−Metalpa et al, 2018). Expanding the scope to include planktonic symbioses, the IMPEKAB project (ANR-15-CE02-0011) applied multi-omics approaches to elucidate how photosymbiotic interactions in both plankton and benthic organisms respond to thermal stress, thus contributing to a more comprehensive understanding of reef ecosystem dynamics and nutrient cycling (Not et al, 2020). At the forefront of recent advances, the CORALGENE project (ANR-17-CE02-0020) represents a landmark initiative that has taken a holistic approach to decode the genomic complexity of the coral holobiont across the Pacific. Coordinated by Serge Planes and embedded within the Tara Pacific Consortium, CORALGENE has leveraged high-throughput sequencing technologies, transcriptomics, and metabolomics to provide a comprehensive census of the genetic and microbial diversity present within coral reefs (See the paper list as www.nature.com/collections/adgaiffggg). This project not only uncovered a vast array of cryptic biodiversity within the coral host, its symbiotic algae (zooxanthellae), and associated microorganisms but also established critical links between genomic variation and environmental adaptation. By sampling across more than 40 island systems and employing cutting-edge meta-barcoding and meta-transcriptomic analyses, CORALGENE has generated robust datasets that reveal how coral holobionts respond to environmental stressors, such as warming and acidification.

Collectively, these projects illustrate the remarkable progress achieved by French research teams through ANR funding. Their integrated efforts highlight the power of a multidisciplinary approach—combining ecological, genetic, and molecular analyses with advanced monitoring and modeling—to deliver groundbreaking insights into coral reef resilience, inform adaptive management strategies, and foster innovative restoration techniques that are essential for safeguarding the future of these vital ecosystems in an era of rapid global change.

2-2 - Innovation for Private Enterprises, for Science Policy, for the Citizen, contribution to human societies.

Coral reefs provide livelihoods, protect shorelines, and hold cultural significance for coastal communities worldwide. ANR-funded projects such as Coral Reefs and LIVE AND LET DIE have shown how reef health directly affects fish populations, tourism potential, and artisanal fisheries. By examining larval settlement and habitat quality, researchers have informed sustainable fishing regulations and ecotourism guidelines that safeguard both economic returns and cultural heritage. In addition, studies from CARiOCA and CORALGENE offer data on coral genotypes more tolerant to warming or acidification, thus guiding reef restoration and mariculture ventures. These findings enable coastal communities to adapt their resource management—shifting from exploitative uses to practices aligned with reef conservation.

Methodological Breakthrough

Projects like IM-MODEL@CORALFISH and CORALGENE pioneered the application of high-throughput sequencing and advanced population genetics models, providing novel insights into reef connectivity and evolutionary history. This integrative genomic and ecological approach supports private enterprises in biotechnology—such as breeding resilient coral strains—and informs science policy by pinpointing critical habitats for protection. Furthermore, through combined remote sensing, in situ sensor arrays, and omics-based analyses, initiatives like ELPASO and IMPEKAB deliver real-time or high-resolution data on environmental variables and ecosystem responses. These methodological innovations yield early-warning systems for coral bleaching events, enabling policymakers to enact timely conservation measures and coastal communities to anticipate changes in fisheries or tourism.

Together, these ten ANR-(co)funded projects underscore the high-level scientific expertise of French research teams in coral reef ecology, molecular biology, climate science, and socio-ecological studies. Through cutting-edge science and innovations that benefit private enterprises, policy-making, and citizens, they collectively address the urgent challenges facing coral reefs. Their methodological breakthroughs—from advanced genomic modeling to integrative sensor networks—provide scalable solutions for coastal communities, informing both local and global strategies for reef conservation and sustainable development.

3 - Research Perspectives

Regarding scientific aspects, collectively, the portfolio of projects points to several key research frontiers. Future studies will increasingly address the combined impacts of warming, acidification, pollution, and overfishing through integrative experimental designs and field monitoring. We must undertake holistic methods that will capture the ecological complexity inherent in coral reef systems. Building on the success of transgenerational experiments, researchers are now exploring epigenetic and microbiome contributions to coral and fish resilience. Refined connectivity and demographic models will be integrated into ecosystem-based management frameworks and may merge with climate forecasting tools. In addition, deeper collaboration with social sciences will help evaluate the human dimensions of reef management, including governance structures, traditional ecological knowledge, and socio-economic trade-offs.

In terms of Innovation, ongoing improvements in autonomous sensors for temperature, pH, and acoustic pollution are leading to broader deployment, moving these technologies from pilot to operational status. Insights into coral–algae symbioses, and the genomic underpinnings of resilience could inspire new reef restoration materials such as thermotolerant coral strains, advanced settlement substrates, or probiotic treatments. Building upon connectivity modeling, the development of integrated reef management dashboards is on the horizon, incorporating real-time environmental data, genetic connectivity metrics, and socio-economic indicators.

Lastly, future perspectives should play a role in the structuration of the communities: National, European, and International Dimensions. Partnerships with institutions in the Pacific (including Papua New Guinea and Australia) and the Indian Ocean (notably Madagascar and La Réunion) facilitate trans-continental research on coral reef adaptation, reinforcing France’s leadership in tropical marine science and its ability to shape global reef conservation agendas. By coordinating resources, standardizing protocols, and pooling data, the French marine research community is well-positioned to expand collaborative projects that unite advanced scientific knowledge with practical management strategies and international policy frameworks.

Overall, this synthesis demonstrates how France’s ANR-funded coral reef and marine biodiversity projects collectively address pressing environmental challenges through pioneering research, innovative methodologies, and active stakeholder engagement. Together, these efforts build a robust foundation for future studies on reef resilience and for the sustainable management of coastal ecosystems worldwide.

Fishes and Fisheries

Climate change, anthropogenic pressures, the stagnation of wild fisheries, and the rise of aquaculture have guided research on fish and marine fisheries over the past 20 years.  108 projects supported by the ANR have led to significant advances in ecosystem-based management (MPAs), the use of co-viability models to evaluate fishing policies, and the development of new monitoring methods such as environmental DNA. Their results show progress in climate and ecological modeling, advances in nutrition and immunology for aquaculture, and innovations for the industry and coastal communities, such as modeling tools and RNA vaccines. The research has also highlighted the impacts of microplastics and pollutants, emphasizing the need for new approaches to risk assessment. Research perspectives include the development of more resilient and low-impact farming models, the diversification of aquaculture, and an ecosystem-based and adaptive management of fisheries to meet the challenges of growing food needs, climate change, and marine pollution.

Gilles Bœuf : MHNN/Obs Banyuls and Didier Gascuel : Inst Agro Rennes

Scientific Background :

At an international level, and over the last 20 years, research into natural fish populations and their exploitation by fishing and aquaculture has been strongly influenced by 4 major concerns:

• Recent decades have been marked by a growing awareness of the already massive impact of climate change on marine resources and ecosystems. In particular, changes in the abundance and distribution of a growing number of marine populations have been highlighted, with cascading effects on fish production potential and the structure and functioning of food webs.
• In addition to climate change, research has focused on the cumulative effects of various anthropogenic pressures (habitat degradation, invasive species, pollution) not only on the state of health and dynamics of marine ecosystems, but also on the food security of seafood products.
• Over the last fifty years or so, the fishing industry has experienced an overall stagnation in production, fundamentally linked to the degradation of available resources and a fall in oceanic productivity. Scientific research has sought to gain a better understanding of the ecological mechanisms underlying this degradation and to develop operational tools for an ecosystem-based approach to fisheries management.
• Marine and inland aquaculture, on the other hand, has seen its production literally explode, with production doubling every 9 years. This development, based on the domestication of new species and the mastery of new production methods, poses particular problems in terms of the impact of aquaculture on the environment. Research has focused in particular on gaining a better understanding of the biology and ecology of species, with the dual aim of improving the zootechnical performance of farms and reducing their environmental impact.

These four major themes also structure the research funded by the ANR.

2 - Main contributions of the French Communities through ANR co-funding

In the field of natural fish populations, fisheries and aquaculture, a great deal of work has been carried out over the period under review, with 76 "ended" projects and 30 "ongoing" projects.

2.1 - Major scientific advances

• For fisheries, populations and natural ecosystems, scientific work has focused mainly on ecosystem-based management, including social impacts, stock estimation, stock/recruitment/climate change interactions, movement modelling, the implementation of MPAs and offshore webs, invasive species, biodiversity protection/exploitation interactions, and very recently the use of AI "machine learning" and environmental DNA to analyse biodiversity and populations in detail.
  
  Significant scientific advances can be identified in the following areas in particular:
  
  • A detailed analysis of physiological processes will provide a better understanding of the impact of climate change, from the individual to the population. For example, we are showing the mechanisms by which a rise in temperature disrupts the triggering of salmon spawning, or the enzymatic synthesis of melatonin, the hormone that controls chronobiology. We are also identifying the synergistic effects of thermal and hypoxic stress, via the energy metabolism of individuals.
  • The coupling of physical, climatic and ecosystem models, and the associated methodological developments, will greatly improve the predictive capacity and reliability of climate change impact scenarios. For example, the work being carried out on pelagic ecosystems is leading to a better understanding and representation of zooplankton dynamics and its effects on exploited populations.
  • These models are also leading to a better understanding of the impact of living organisms on the dynamics of carbon flows in the ocean. One programme, for example, has highlighted the impact of bacteria and gelatinous organisms on the carbon pump.
  • By identifying the trophic role of certain key species or groups, we can better anticipate the risks associated with climate change. This is the case, for example, with the lanternfish, whose decline in abundance could lead to the extinction of certain colonies of sub-Antarctic predators. Cryptobenthic fish play a key role in the resilience of coral reefs.
  • The development of population genetics approaches, and in particular genetic mark-recapture methods, opens up prospects for assessing population abundance independently of fisheries data.
  • One operational application of this research is the development of decision-making tools for ecosystem-based fisheries management. Progress in this area still seems fairly preliminary, but several projects are proposing new indicators of the state of health of ecosystems and new procedures for issuing scientific advice in this direction.
  • More generally, co-viability approaches aim to analyse the effects of different fisheries management scenarios on the ecological and economic viability of fisheries socio-ecosystems, in the context of climate change. In particular, this work shows the high risks associated with business-as-usual scenarios.
  • More and more is known about the effectiveness of Marine Protected Areas (MPAs). In particular, it has been shown that the level of protection is essential for preserving biodiversity. Conversely, and quite logically, MPAs appear to be ineffective for conserving species with a high rate of movement or for managing invasive species. Non-spatial management appears preferable here.
  • Finally, we note that work in historical ecology offers new perspectives that partly challenge our perceptions of the conservation or restoration of marine species. For example, this work has shown how early cetaceans were exploited and how their current abundance has been reduced by a factor of 20 or 40 compared with the Palaeolithic period.
• For aquaculture, work on nutrition (replacement of animal proteins in the diet) and nutritional quality, reproductive physiology, including sex determination, pathologies and prophylaxis, including vaccination, control of metamorphosis, genetics (identification of populations and species, estimation of variability, evolutionary markers, improvement, etc.), in fact the biological bases of aquaculture.
  
  Significant progress has been made in these areas, and more specifically:
  
  • The ecology of previously little studied groups is now better understood: coral fish, for example, or holocephalus or syngnathus,
  • The fundamental knowledge needed to improve farm management is progressing, particularly in terms of nutrition.
  • Research is focusing in particular on the replacement of animal proteins in the diet of salmonids (fishmeal, a source of overexploitation of natural resources), and on the work focuses on nutrition (replacement of animal proteins in the diet) and nutritional quality and on the organoleptic quality of finished products from various species of fish. We are particularly interested in the vegetalisation of feed and the assimilation of carbohydrates.
  • New approaches such as Integrated Multi-Trophic Approaches or Aquaponics offer promising prospects for development, particularly in terms of significantly reducing the environmental impact of aquaculture.
  • In the field of reproductive biology, numerous studies have been carried out on the genesis and development of fish. détermination du sexe, salmonidés, esturgeons, bar… et sur les interactions avec les polluants (PCB, PBDE).
  • The use of AI, environmental DNA and, more generally, genomic approaches is increasing, as tools to assist in the management and optimisation of fish farms,
  • New knowledge has been acquired about the effectiveness of the immune system (including the role of interferons) in fish, as well as the role of cutaneous microbiota (mucus) and intestinal microbiota.

- On the question of climate/pollution interactions, a great deal of work has been carried out on the study of and solutions to ocean pollution, chemical exposomes after exposure to pollutants, the effects of microplastics, the fate and effects of contaminants, climate/contamination interference, pharmaceutical residues, a focus on endangered species (eels, sturgeons, sharks, holocephalans, syngnaths, etc.), the role of epigenetics, etc.

These works have provided major insights into pollution/physiology interactions in various species of fish, including coral reefs, salmonids, hake and other coastal species, as well as Gambusia. Pollution by micro-plastics is a major concern, as is the persistence of pharmaceutical residues and endocrine disruptors in the sea and rivers. Trans-generational effects have been observed and must be considered as a major point of vigilance. A presentation was made on the use of bio-materials to counter the damage caused by UV rays.

2.2 Innovations for businesses and coastal communities

With regard to fisheries, innovative socio-ecological modelling, assessment and scenario tools have been developed to improve ecosystem-based management in all types of environment, from the Arctic to tropical seas, in order to implement methods focusing on the sustainability of operations, both on fish and invertebrates, sea urchins or clams for example. The use of FAD stations for oceanic observation appears relevant. Biodiversity/fisheries co-viability coupling models are very attractive, as are approaches to historical fishing activities and the issue of invasive species, in the Mediterranean for example with rabbitfish or coral ecosystems.

In terms of aquaculture, various models have been developed on the future of the activity, in Europe and elsewhere, on various social systems and with the formation of international networks. New sanitary treatment and vaccination techniques (including RNA vaccines for trout and carp) have been developed to combat infectious diseases and parasites. The interactions between well-fare and zootechnics have been analysed in fish farming. Various neuropeptides and other molecules have been extracted from algae, for use in pharmacology and cosmetics. Two original projects were carried out, one on the origin of methyl-mercury in the sea, the other on molecular markers of developmental competence in fish eggs.
Finally, there are programmes to improve the quality of seafood products, including the development of electronic chips to monitor storage temperatures throughout the production chain, and the development of automatic parasite detection techniques. Work on identifying communities of bacteria that affect product quality has led to the exploration of promising control strategies based on the use of competing bacteria.

3 - Research Perspectives

Today, maritime activities have a strong need for scientific research and organisation. When you consider that we had to wait until COP21 in Paris for us to finally considering the influence of the ocean on the climate and the influence of the climate on the ocean, you can imagine the current issues. They arise against a backdrop of destruction and contamination of coastlines almost everywhere in the world, over-exploitation of resources, both living and in the future mineral, uncontrolled spread of species, including invasive species (the "ecological roulette"), and accelerating climate change causing hypoxia or even anoxia, hypersalinisation, excessively high temperatures and a sudden rise in sea levels.

Fisheries are in a development situation that often fails to take into account the degraded state of the resource and the ecosystemic impacts of exploitation. In return, they have to deal not only with pollution problems, but more generally with the deleterious effects of the erosion of marine biodiversity. In recent years, we have witnessed growing instability in ecosystems and an increase in the chaotic evolution of resources. These changes pose major challenges for research, in terms of understanding them better, anticipating them if possible and identifying the most appropriate adaptation strategies.

Aquaculture, for its part, is faced with the issue of feeding carnivorous species (salmonids, marine fish such as yellowtail, sea bass or sea bream), massive coastal destruction (mangroves for shrimps), coastal pollution (problems for molluscs and algae), and a climate that is changing too quickly. We also need to encourage work on ecosystem-based management of fisheries, and research into alternative production models that have less impact on the environment and are more resilient (herbivorous species, multi-trophic approach, etc.). From this point of view, there seems to be an urgent need to move away from research based solely on the "salmon model", which is increasingly criticised regardless of the progress made on the nutritional front. There is also an ongoing need to develop solid biological foundations for aquaculture in terms of genetics, nutrition, physiology and pathology studies. All of this needs to be done in a climate of major changes of all kinds, including access to a globalised market.

1 - Aquatic invertebrates and aquaculture

2 - Benthic invertebrates : Macrozoobenthos. A key component of marine ecosystems functions, services and a source of bioinspiration

Invertebrates play an essential role in marine ecosystems, particularly in contributing to sediment dynamics and carbon sequestration. They also serve as excellent bioindicators for assessing the good ecological status of an ecosystem. Furthermore, invertebrates are a source of inspiration for innovations in bioinspiration, particularly in the fields of robotics and adhesive materials. Research supported by the ANR has focused, for example, on combating diseases affecting oysters and defining strategies for resilience against these pathologies. In the context of the fight against climate change, analyzing the genomic adaptation capacity of invertebrates to a changing environment also opens important perspectives for the control of invasive species.

1 - Aquatic invertebrates and aquaculture

Tristan RENAULT, Ifremer

1) Scientific background

Invertebrates constitute a very significant part of the biodiversity within aquatic ecosystems. They occupy a place there, in particular as sources of food for other species or by degrading organic matter. Invertebrates are present in all ecological niches of these ecosystems: water column, water-sediment interface, sediment, plants or algae, etc. These are therefore excellent indicators of environmental quality. As part of the policies implemented for the protection of aquatic ecosystems and the management of the resources they contain (WFD, 2003), networks have been developed targeting aquatic invertebrates and the evolution of their populations in time and space, these evolutions reflecting the good ecological state or not of the environments monitored.

Some species of aquatic invertebrates are also exploited, particularly for human consumption in a global context of development in recent decades of aquaculture activities. Global aquaculture production continued to grow in 2020 (FAO, 2022). The total production of global aquaculture in 2020 was 122.6 million tons. Over the period 1990-2020, this production increased with an average annual growth rate of 6.7%. The average annual growth rate gradually decreased, from 9.5% over the period 1990-2000 to 4.6% over the period 2010-2020. It fell further to 3.3% per year in recent years (2015-2020). Alongside the declining growth rate in relative terms, it is important to note the net increase in global production in absolute terms over the three decades (FAO, 2022).

In 2020, production of invertebrate species amounted to 17.7 million tons of molluscs (29.8 billion USD) - mainly bivalves -, 11.2 million tons of crustaceans (81.5 billion USD) and 525,000 tons of aquatic invertebrates other than molluscs and crustaceans (2.5 billion of USD) (FAO, 2022). Shrimp dominate coastal shellfish aquaculture production in brackish water ponds and are an important source of foreign exchange earnings for some developing countries in Asia and Latin America. In terms of quantity, China's production of marine molluscs far exceeds that of all other producers combined. In some major producing countries, however, marine bivalve farming represents a significant percentage of total aquaculture production of aquatic animals (New Zealand, France, Spain, Republic of Korea, Italy and Japan).

These contextual elements should be linked to the fact that over the period 2005-2025, ANR financed/co-financed around 30 projects targeting marine invertebrates both to better understand their biology and to understand the hazards that affect them.

2) Main Contributions of the French Communities through ANR co-funding

In the context described above, ANR over the period considered financed or co-financed subjects more particularly targeted on (1) diseases and associated pathogens affecting aquatic invertebrates, (2) biological risks (viruses and algal toxins) and their control in relation to shellfish consumption by humans or even (3) the exploitation of marine invertebrates in a context of global change and understanding of the mechanisms at work in terms of adaptation and evolution. It should be noted, however, that it is the diseases affecting marine bivalves and the infectious agents responsible for these diseases which have been the most studied in a context of changing environmental conditions and the emergence of mass mortality phenomena.

2-1 Diseases and pathogens affecting aquatic invertebrates

Over the period 2005-2025, around ten projects enabled the acquisition of knowledge on diseases affecting aquatic invertebrates and more particularly oysters. This relatively high number of projects undoubtedly finds its source in the economic importance of shellfish farming in France and the hazards it has faced in recent decades, infectious diseases being a major hazard for aquaculture activities. (VIBRIOGEN - ANR-11-BSV7-0023 - Les vibrions pathogènes d’invertébrés marins : un nouveau regard sur la virulence et les réservoirs de gènes permettant l’adaptation à la niche écologique ; OPOPOP - ANR-13-ADAP-0007 - Emergence de pathogènes opportunistes d'huîtres dans des populations naturelles de Vibrio ; REVENGE - ANR-16-CE32-0008 - L'huître comme niche de l'évolution et l'émergence de vibrios pathogènes ;ENVICOPAS - ANR-15-CE35-0004 - Impact des changements environnementaux sur les organismes pathogènes dans les écosystèmes côtiers ; GIGASSAT - ANR-12-AGRO-0001 - Adaptation des écosystèmes ostréicoles au changement global ; DECIPHER - ANR-14-CE19-0023 - Déchiffrage des maladies multifactorielles: cas des mortalités de l'huître ; DECICOMP - ANR-19-CE20-0004 - Déchiffrer toute la complexité du syndrome de mortalité des huîtres du Pacifique pour modéliser le risque épidémiologique ; PRIMOYSTER - ANR-22-CE20-0017 - Exploration des capacités de priming immunitaire chez l'huître ; IDEAL - ANR-23-CE35-0009 - Impact des données génomiques sur le contrôle des maladies des mollusques marins).

In the marine environment, there are populations of vibrios presenting infectious risks for farmed species. Thus, it was possible to identify populations (or species) of vibrios at risk (Lemire et al., 2014, Bruto et al., 2017) for cupped oysters (Vibrio tasmanienis, V. crassostreae) and farmed shrimp (V. nigripulchritudo) and to highlight original mechanisms (Goudenège et al., 2015; Rubio et al., 2019) by which these bacteria kill their hosts (in the Pacific oyster: invasion of hemocytes, resistance of bacteria to copper, cooperation between vibrios; in shrimps, expression of a previously unknown toxin).

The spatio-temporal dynamics of microbial communities, including pathogenic vibrios, and the environmental factors influencing their distribution, have been studied in particular in France and Germany by combining broad (metabarcoding) and specific (MALDI-TOF MS) approaches. In seawater, bacterial communities exhibit seasonal dynamics correlated with temperature and salinity. The data obtained contributed to enriching existing databases on bacteria (vibrions). Bacteria belonging to the genus Vibrio (or vibrios) constitute a family of ubiquitous heterotrophic bacteria found in marine environments. Although they represent only a small percentage of total marine bacteria, vibrios can predominate during blooms. These blooms are regulated at least in part by bacteriophages (or phages), viruses that specifically infect bacteria. Phages thus influence the abundance and diversity of vibrios and show a strong specificity for co-occurring vibrios due to i) specific receptor(s) and; ii) resistance mechanisms in the host. Thus, the vibrio pathogenic for the Pacific oyster, V. crassostreae, is structured into epidemic clades whose virulence depends in part on the presence of a plasmid. Each genomic group of phages specifically adsorbs to a clade of V. crassostreae, but their multiplication depends on the presence of resistance genes in the host and/or counter-resistance genes in the phage (Piel et al., 2022; Cahier et al., 2023).

Furthermore, to assess the environmental and economic situation of shellfish ecosystems in France and analyze the emergence of massive mortality outbreaks affecting Pacific oysters, results from observations, experiments and modeling acquired at different spatial and temporal scales were combined. Thus, to understand the factors that govern the spatial distribution and spread of diseases in the Pacific oyster, Magallena/Crassostrea gigas, (1) the key epidemiological parameters for agents such as the bacteria V. aestuarianus have been identified (Parizadeh et al., 2018; Lupo et al., 2020), (2) experiments in a controlled environment carried out highlighting the effect of temperature, salinity, acidification, phytoplankton and the physiology of the Pacific oyster on the transmission of diseases and associated mass mortality episodes (Lupo et al., 2019), and (3) the geographical variations of mortalities analyzed in relation to environmental parameters in a natural environment (Pernet et al., 2014a; Pernet et al., 2014b; Renault et al., 2014). The environment thus plays a major role in the risk of mortality caused by infectious diseases in the Pacific oyster. The impact of temperature on the development of infections caused by OsHV-1 or V. aestuarianus has been shown experimentally in M./C. gigas. At the scale of a bay, the density of oysters influences the prevalence of infections and the water temperature acts on the speed of propagation of these infections (Renault et al., 2014). A model of disease transmission and mortality of Pacific oysters taking into account epidemiological, hydrodynamic parameters and contact structures of oyster populations was thus constructed for V. aestuarianus infection (Prazadeh et al., 2018; Lupo et al., 2019, Lupo et al., 2020). This model makes it possible to compare disease management measures (regulation of transfers, density management). Using experimental infections reproducing the natural route of infection and combining thorough molecular analyses of Pacific oyster families, it was shown that mass mortality episodes affecting Pacofoc oyster spat were related to multiple infection with an initial and necessary step of infection by OsHV-1 (de Lorgeril et al., 2018). Viral replication leads to the host entering an immune-compromised state, evolving towards subsequent bacteraemia (de Lorgeril et al., 2018 ; Oyanedel et al., 2023).

Taking advantage of an invertebrate species, the Pacific oyster, in which one of the longest and most effective periods of protection against OsHV-1 infection is observed in an invertebrate was reported, the first comprehensive transcriptomic analysis of antiviral innate immune priming was provided (Lafont et al., 2020). Priming with poly(I·C) induced a massive upregulation of immune-related genes, which control subsequent viral infection, and it was maintained for over 4 months after priming (Lafont et al., 2020). These recent advances have shown that the innate immune system of invertebrates can develop memory mechanisms (innate immune memory, immune priming or trained immunity) allowing for efficient protection against infectious diseases. Moreover, UV-inactivated OsHV-1 is also a potent elicitor of immune priming. Previous exposure to the inactivated virus was able to efficiently protect oysters against OsHV-1 infection, significantly increasing oyster survival (Morga et al., 2024). This exposure blocked viral replication and was able to induce antiviral gene expression potentially involved in controlling the infection. Finally, this phenomenon can persist for at least 3 months, suggesting the induction of innate immune memory mechanisms (Morga et al., 2024). New ways to train the Pacific oyster immune system are unrealed and could represent an opportunity to develop new prophylactic strategies to improve health and to sustain the development of marine mollusk aquaculture (Dantan et al., 2024 ; Montagnani et al., 2024).

2-2 Shellfish contamination and consumer health

Concerning this theme, ANR has more particularly financed/co-financed scientific projects targeting toxic microalgae or even noroviruses.

The projects MODECOPHY (ANR-06-SEST-0023 - Modélisation des mécanismes de contamination des coquillages par des phycotoxines), ACCUTOX (ANR-13-CESA-0019 - De la caractérisation des déterminants de l’accumulation des toxines paralysantes (PST) chez l’huître (Crassostrea gigas) au risque sanitaire pour l’homme dans son contexte sociétal) or event HABIS (ANR-22-CE20-0024 - Efflorescences de microalgues toxiques (HAB) : une menace pour la durabilité des bivalves commercialement exploités?) made it possible to explore the determinants of phycotoxin accumulation and the underlying mechanisms in Pacific oysters. Harmful and toxic microalgae blooms or HABs (Harmful Algal Blooms) are indeed becoming more and more frequent and intense across the globe. These HABs are now considered as a major environmental, societal and economic concern for the sustainability of marine ecosystems and their uses and appear as a scientific challenge in research strategies (Paris Agreement, UNESCO). Toxic microalgae have significant harmful effects on the ecology of coastal ecosystems, the structure of marine communities and the life traits of marine species as well as along the trophic chain they support, as well as an economic cost of more than 800 million euros/year in Europe alone.

Harmful algal blooms of Alexandrium spp. dinoflagellates regularly occur in French coastal waters contaminating shellfish. Studies have demonstrated that toxic Alexandrium spp. disrupt behavioural and physiological processes in marine filter-feeders, but molecular modifications triggered by phycotoxins are less well understood. The mRNA levels of 7 genes encoding antioxidant/detoxifying enzymes were thus analyzed in gills of Pacific oysters exposed to a cultured, toxic strain of A. minutum, a producer of paralytic shellfish toxins (PST) or fed Tisochrysis lutea, a non-toxic control diet (Fabioux et al., 2025). Transcript levels of sigma-class glutathione S-transferase (GST), glutathione reductase (GR) and ferritin (Fer) were significantly higher in oysters exposed to A. minutum compared to oysters fed T. lutea. The detoxification pathway based upon glutathione (GSH)-conjugation of toxic compounds (phase II) is likely activated, and catalyzed by GST. This system appeared to be activated in gills probably for the detoxification of PST and/or extra-cellular compounds, produced by A. minutum. GST, GR and Fer can also contribute to antioxidant functions to prevent cellular damage from increased reactive oxygen species (ROS) originating either from A. minutum cells directly, from oyster hemocytes during immune response, or from other gill cells as by-products of detoxification (Fabioux et al., 2015). A flow-cytometric (FCM) approach was also develpped to evaluate A. minutum cellular responses to mechanical and chemical stresses. FCM analysis and sorting, and microscopic observations permitted identification and characterization of five cellular states/forms of A. minutum; (1) vegetative cells, (2) pellicle cysts, (3) degraded cells, (4) empty theca, and (5) dead cells (Haberkorn et al., 2015). Experiment assessing kinetics of excystment indicated that it can occur rapidly following mechanical stress (centrifugation). Moreover, upon 30 min of exposure to chemical stressors (saponine and H2O2), only vegetative cells, pellicle cysts, and dead cells were detected. Overall, encystment–excystment of A. minutum upon changes of environmental conditions can occur very rapidly (Haberkorn et al., 2015).Furthermore, Pacific oysters, M./C. gigas, after being experimentally contaminated by A. minutum were fed S. costatum. Decontamination rates are higher than those observed in coastal environments. Feeding S. costatum significantly reduces the time needed to reach the health threshold (Gueguen et al., 2008).

Through the project COQUENPATH (ANR-06-SEST-0008 - Rôle des coquillages et de l'environnement marin sur la sélection de souches de Norovirus, humaines/animales, pathogènes pour l'homme), the role of the marine environment, and in particular shellfish, on the selection of human or animal norovirus strains was explored. Shellfish were selected as a food model that could promote the zoonotic potential of noroviruses through their filtration activity. Noroviruses are non-enveloped single-stranded RNA viruses (therefore very resistant) and certain shellfish production sites are in coastal areas contaminated by waste from intensive pig or cattle farming. The sequence similarities of bovine and porcine noroviruses with human strains suggest that these animals could, through the genetic evolution of these strains, constitute a reservoir for humans. Based on previous observation of a specific binding of the Norwalk strain (prototype norovirus genogroup I) to the Pacific oyster digestive tract through an A-like carbohydrate structure indistinguishable from human blood group A antigen and on the large diversity between strains in terms of carbohydrate-binding specificities, the different ligands implicated in attachment to oysters tissues of strains representative of two main genogroups of human noroviruswere evaluated were explored. The GI.1 and GII.4 strains differed in that the latter recognized a sialic acid-containing ligand, present in all tissues, in addition to the A-like ligand of the digestive tract shared with the GI.1 strain (Maalouf et al., 2010). Furthermore, bioaccumulation experiments using wild-type or mutant GI.1 showed accumulation in hemocytes largely, but not exclusively, based on interaction with the A-like ligand. Moreover, a seasonal effect on the expression of these ligands was detected, most visibly for the GI.1 strain, with a peak in late winter and spring, a period when GI strains are regularly involved in oyster-related outbreaks (Maalouf et al., 2010). These observations may explain some of the distinct epidemiological features of strains from different genogroups.

2-3 Exploitation of marine invertebrates in a context of global change and understanding of the mechanisms at work in terms of adaptation and evolution (projets Hi-Flo - ANR-08-BLAN-0334)

The genetic basis and history of adaptive differentiation in high gene flow marine species ; Gametogenes - ANR-08-GENM-0041 - Génomiques de la gamétogénèse chez l'huître creuse Crassostrea gigas ; MEET - ANR-20-CE02-0024 - Les Moules du genre Mytilus et leur Environnement: une Exploration de leurs phénotypes et de leurs génomes à travers le Temps ; IMTA-EFFECT - ANR-15-COFA-0001 - Integrated Multitrophic Aquaculture for EFFiciency and Environmental ConservaTion ; SIMTAP - ANR-18-PRIM-0017 - Self-sufficient Integrated Multi-Trophic AquaPonic systems for improving food production sustainability and brackish water use and recycling ; MANA - ANR-16-CE32-0004 - Gestion des Atolls)

Recent advances in DNA sequencing techniques now make it possible to analyze a very large number of genes simultaneously, what is called a “genomic scan”. By comparing the frequency of alleles in populations encountering different environmental conditions, it is possible to identify genes which present differences in allelic frequencies greater than those observed on other genes in the genome. These genes are located in regions of the genome under the influence of selection. Genomic scans were carried out in five species of marine invertebrates – the Pacific oyster, the flat oyster, the mussel, the crepidula and a tellina – by comparing more or less distant populations and also populations that have recently invaded a new geographical area following their introduction by humans. Thus, selected genes were detected very easily in the original areas inhabited by the species for many generations, whereas no or few selected loci were identified in the areas where the species were introduced. Adaptive polymorphisms are ancient polymorphisms, which have segregated in populations for a long time and which may even have crossed species boundaries (Rohfritsch et al., 2013). The history of genetically differentiated populations often results from secondary contact between populations that had been geographically isolated in the past. The hypothesis according to which the adaptation of marine species would involve the long-term evolution, and in a geographical context probably different from the current context, of various genetic mechanisms – local adaptation, hybridization depression, partner choice – which combine their effects by genetic coupling could thus be developed (Rohfritsch et al., 2013).

The analysis of the DNA entrapped in ancient shells of molluscs has the potential to shed light on the evolution and ecology of this very diverse phylum. Ancient genomics could help reconstruct the responses of molluscs to past climate change, pollution, and human subsistence practices at unprecedented temporal resolutions. To improve ancient shell genomic analyses, high-throughput DNA sequencing was applied to Mytilus mussel shells dated to ~111-6500 years Before Present, and investigated the impact, on DNA recovery, of shell imaging, DNA extraction protocols and shell sub-sampling strategies. All layers that compose Mytilus shells, i.e., the nacreous (aragonite) and prismatic (calcite) carbonate layers, with or without the outer organic layer (periostracum) proved to be valuable DNA reservoirs, with aragonite appearing as the best substrate for genomic analyses (Martin-Roy et al., 2024)

Furthermore, the physiological and genetic bases of reproduction and associated metabolisms in the Pacific oyster, have been studied. This species belonging to the phylum Lophotrochozoa, it is located in a key phylogenetic position among bilaterian animals and offers the opportunity to examine in a comparative context the evolution of genes involved in processes related to reproduction. Oysters produce gametes in abundance and release them into seawater where fertilization takes place. This high fertility makes it possible to compensate for significant mortality during the early stages of development. As a result, gametogenesis has a major impact on many physiological functions causing genetic and phenotypic trade-offs between reproduction, growth and survival. Gametogenesis is also a biological process whose control is important in the context of aquaculture of this species. In this context, networks of genes specifically expressed during the process of gametogenesis in gonadal tissue during an annual reproductive cycle were highlighted thanks to the implementation of high-throughput transcriptomic techniques (DNA chips) and real-time PCR. This approach led to the identification of markers (1) of reproductive stages and (2) of sex determination in a hermaphrodite species with irregular protandry, as well as genes whose expression is linked to reproductive investment (Dheilly et al., 2012). With the prospect of combining genetic and phenotypic data, some innovative post-genomic methodologies (RNA interference (RNAi), reverse endocrinology or pharmacological approaches) have been developed and adapted to explore the function of certain genes involved in reproductive processes. These methods constitute an essential step in the genetic and functional exploration of the oyster with the aim of domesticating or improving traits of interest for aquaculture and understanding the impact of environmental changes on the physiology of this sentinel species. The “GigasDataBase” database was thus enriched and a new expression database bringing together all the qualitative and quantitative transcriptional data in the Pacific oyster was constructed (Fleury et al., 2009).

Integrated multi-trophic aquaculture (IMTA) is a promising perspective to develop efficient and environmentally friendly aquaculture. Different case studies revealed that in IMTA, adapted management of the interaction between species of different trophic groups permits to improve the aquaculture system (Cunha et al., 2019). The overall productivity of the integrated systems compared to the reference fish monoculture can be increased by the production of other products and/or services. It globally increases the efficiency of fish feeding by recycling within the system loop and therefore, limits the environmental impacts. IMTA permits also diversification of the aquatic products, contributing to aquatic farm robustness. The key role of primary producers (plants, micro and macro algae) as the engine for nutrient recycling was documented. Their role in the regulation of gas (CO2 and O2) and water quality was shown as they can dramatically reduce the water concentration in nitrogen and phosphorus. Conversely, the positive effect of fish and bivalves on the productivity of primary producers overpass the simple exchange of nutrients (Cunha et al., 2019). As examples, the bivalves can increase the water transparency and favor photosynthesis and oxygen availability in coastal ponds.

3) Research perspectives

In a context of accelerating climate change and global change and their attendant dangers and risks, two major challenges for our societies today seem to face each other: that of food security in a world with ever-increasing demographics and that of the preservation/restoration of biodiversity and ecosystems for future generations.

Aquatic ecosystems are at the heart of these two issues and their combination. On the one hand, these ecosystems are central through the biological resources exploited by fishing and aquaculture, ensuring a primary contribution in terms of food globally. On the other hand, these ecosystems and the species they host are under increasing pressure linked to environmental changes induced by human activities (exploitation of living resources, releases of contaminants, diversified developments and activities, etc.) eroding biodiversity and modifying ecosystems. Climate change is already at work and increasingly significant anthropogenic forcing is leading aquatic ecosystems onto transition trajectories, beyond their resilience (Sayer et al., 2025). It is therefore essential to think in terms of multiple interactions and transitions and no longer in terms of equilibrium compromises. The major issue today is indeed a form of paradigm shift by ensuring that the ecosystem approach, which could also be described as an approach based on the One Health concept, becomes a form of preamble to any reflection concerning the development of human activities linked to these environments.

In this context, it is necessary to continue work concerning (1) the knowledge and characterization of the biodiversity of aquatic invertebrates to better preserve them, (2) the understanding of the functioning of aquatic ecosystems and the development of tools to support their good ecological status, (3) support for the sustainable development of the exploitation of biological resources (aquatic invertebrates) through fishing and aquaculture and (4) the valorization of marine biological resources through biotechnologies. But, the primary challenge in terms of scientific work must focus primarily on (1) an essential evolution of the observation of aquatic environments in their biological and ecosystem components in a context of multiple and complex interactions through an integrated and non-targeted observation of tomorrow, and (2) the development of management scenarios for these ecosystems through modeling and their sharing with society in all of its components.

2 - Benthic invertebrates : Macrozoobenthos. A key component of marine ecosystems functions, services and a source of bioinspiration.

Eric FEUNTEUN, MNHN et EPHE

1.1. Scientific background

Marine benthic habitats cover the seafloors of the ocean throughout the world, from the intertidal zone to the depths of 11000 m in the Mariana Trench. Benthic habitats comprise a high diversity of chemico-physical conditions as temperature, salinity, pressure, light, nutrients and also by the nature of the substrate which can be mineral or biotic. Mineral substrate is mainly described in terms of granulometry and complexity especially of the architecture of the seafloor. This extremely high diversity of habitat conditions results in an equally extreme specific and functional biodiversity. Marine benthos, that refers to the community of organisms that live, in, on or near the seafloor, include a wide range of organisms as animals, vascularised plants and algae and microorganisms that are adapted to the diversity of environmental conditions that are found from the shallow areas to the deep ocean floor. Marine zoobenthos can be classified by size into three main categories of size: Microzoobenthos (<0,1 mm), Meiozoobenthos (0.1 to 0.5mm), Macrozoobenthos (0.5 to 100mm) the largest organisms forming Megazoobenthos. These organisms play key roles in energy transfer, nutrient recycling, sediment stability and dynamics, bioengineering ecosystems through creation of biogenic reefs and carbon sequestration.

Macrozoobenthos includes mollusks, crustaceans, polychaetes, echinoderms, bryozoans, cnidarians, and other taxa. These organisms play key roles in nutrient cycling, sediment mixing, and food webs, and serve as bioindicators of environmental health. The exact number of species is still not properly known, since new species are described each year, and deep seafloor species remain badly described. According to WORMs, macrozoobenthos likely includes hundreds of thousands of species, with mollusks (85,000 species), crustaceans (67,000 species) and annelids (12,000 species) being the most diverse phyla. The diversity is especially high in shallow waters such as coral reefs and coastal ecosystems, with deep-sea environments also contributing substantial but less explored diversity.

Macrozoobenthos occupy soft-bottom habitats where burrowing species (bivalves, polychaetes and crustaceans, hard-bottom habitats that are characterized by sessile organisms (e.g., sponges, bryozoans, corals) and vagile species (crabs, gastropods, cephalopods,..) dwell in the immediate vicinity. Coral Reefs considered as biodiversity hotspots, support a wide variety of benthic invertebrates, including corals, sponges, and echinoderms. Deep sea environments host a diverse number of species that are specialized in extreme environments, especially around deep-sea vents where organisms rely on chemosynthesis rather than photosynthesis for energy.

Four main categories of functional groups may be distinguished: Filter feeders (e.g., bilvalves, bryozoans, sponges, annelids, …) are thought to depend on / control water quality; Deposit feeders (e.g. sea cucumbers, polychaetes, bivalves) are known to modify the sediments and recycle organic matter; Grazers and Predators (e.g. crabs, gastropods, sea stars, cephalopods, ) regulate key populations; while Scavengers and Decomposers (including a range of benthic invertebrates, like some types of worms, crustaceans, …) break down organic matter, recycling nutrients back into the ecosystem.

Macrozoobenthic communities are influenced by a number of factors that are mainly structured according to: depth and light availability, where shallow waters usually receive more light and support a higher biodiversity. As the depth increases light decreases and species are adapted to lack of light and may switch to alternative energy sources. Substrate type (soft, hard, ), temperature and salinity are also key control factors of the benthic communities.

To sum up, marine benthic invertebrates exhibit extraordinary diversity in their form, function, and habitats they use, shape and form. Their diversity is driven by a combination of biological, ecological, and environmental factors, making them crucial components of marine ecosystems.

1.2. Recent progress

1.2.1. Bioindication

Thanks to these properties, macrozoobenthos is currently used for bioindication of marine environment’s quality and resilience. During the last 20 years, new biotic indices, such as refined AMBI and multimetric approaches, have improved ecosystem assessments. DNA-based methods (eDNA, metabarcoding) enhance species detection, while AI and remote sensing aid large-scale monitoring. Macrozoobenthic indicators now assess deep-sea and polar ecosystems, track climate change, and evaluate restoration efforts. These advancements align with environmental policies like the Marine Strategy Framework Directive (MSFD), which mandates monitoring of benthic ecosystems to achieve Good Environmental Status (GES). Improved bioindication ensures better marine conservation, pollution assessment, and ecosystem management. Additionally, emerging seascape ecology integrates spatial patterns, habitat connectivity, and environmental gradients to better understand macrozoobenthic community dynamics in changing marine environments.

1.2.2. Bioinspiration

Marine macrozoobenthos inspire innovations in materials science, robotics, and environmental engineering. Mussels and barnacles have led to bioinspired adhesives and antifouling surfaces, while sea stars and polychaete worms influence soft robotics for underwater exploration. Bivalves inspire water filtration systems, and burrowing organisms inform self-anchoring technologies and sediment stabilization. These adaptations support advances in medicine, nanotechnology, and sustainable engineering. As research expands, macrozoobenthic bioinspiration will drive further innovations in marine technology and conservation.

1.2.3. Biomedical issues

Based on the biology and physiology of macrozoobenthic species, there have been stunning biomedical advancements in wound healing, regenerative medicine, and drug discovery. Mussel and barnacle adhesives lead to bioinspired medical glues for surgeries, while echinoderms and polychaete worms provide insights into tissue regeneration. Polychaete worms, such as Nereis species, have been studied for graft transfer, as their hemoglobin-rich coelomic fluid enhances tissue oxygenation and healing in transplants. Macrozoobenthic compounds, such as bryostatins from bryozoans and saponins from sea cucumbers, show potential in cancer treatment, antimicrobial therapies, and neuroprotection. Mollusk-derived chitin and calcium carbonate structures aid in bone grafts and biodegradable implants, expanding medical applications.

1.2.4. Responses to global change

Recent research on the resilience of zoobenthic communities to global change has focused on several key areas. Studies show that ocean acidification and global warming affect species differently, with some showing adaptive potential (genetic or phenotypic plasticity) to cope with changing conditions. Functional diversity within communities enhances resilience, as species perform overlapping ecological roles, supporting ecosystem processes. Habitat complexity and the availability of refugia are critical for species survival during extreme events. Genetic adaptation and microbial symbioses also help certain species cope with stress. Furthermore, research highlights the synergistic effects of multiple stressors, such as pollution, eutrophication, and overfishing, which can exacerbate the impacts of climate change. Long-term monitoring programs and predictive models are helping to understand how zoobenthic communities will respond to future environmental shifts, providing insights into how ecosystems might adapt or recover.

1.2.5. MPAs: an efficient solution to protect marine biodiversity ?

Marine Protected Areas (MPAs) have significantly benefited macrozoobenthic communities by protecting essential habitats, such as seagrass meadows and coral reefs, from destructive activities like bottom trawling. MPAs increase biodiversity, allow overexploited species to recover, and enhance ecosystem functions like nutrient cycling and sediment stabilization. They provide refuges that promote resilience to climate change and ocean acidification, helping species adapt over time. Additionally, MPAs serve as research sites, offering insights into ecosystem recovery and the long-term impacts of protection and to responses to global change.

However, recent research highlights several limitations of Marine Protected Areas (MPAs). MPAs are often too small or isolated, limiting their ability to support large zoobenthic populations. Incomplete protection, such as allowing certain human activities, can reduce their effectiveness. Pollution and habitat degradation outside MPAs, along with slow recovery of some species, further hinder their success. MPAs also offer limited protection against global stressors like ocean acidification and warming. Additionally, insufficient monitoring and enforcement can lead to illegal activities that undermine conservation efforts.

2. Main Contributions of the French Communities through ANR co-funding

2.1. France’s Commitment to Macrozoobenthos communities.

France has made significant contributions to the study of macrozoobenthos through ANR (Agence nationale de la recherche) funding. Some of the funded projects have produced cutting-edge research addressing gaps in marine science. For example, BENTHOVAL introduces a focus on functional diversity in benthic communities, shifting the emphasis from species richness to the ecological roles of species within ecosystems. This approach provides valuable insights for ecosystem-based management and highlights the importance of maintaining ecological functions to sustain ecosystem resilience. AGEsyMar challenges traditional views of species' resilience by considering aging as a significant factor in adaptation to environmental stress, offering a new understanding of life-history traits and their role in marine ecosystem stability. The CHorMedFin project focuses on the ecological role of marine invertebrates, such as echinoderms, polychaetes, and mollusks, in coastal ecosystems. It investigates their impact on sediment structure, nutrient cycling, and food webs in Mediterranean coastal habitats. By understanding how these invertebrates interact with their environment, the project provides critical information on how climate change, pollution, and habitat degradation affect marine biodiversity and ecosystem functions. The findings contribute to marine ecosystem management by assessing the importance of invertebrates in maintaining the health and functionality of coastal ecosystems. Finally, BIONECAL enhances the use of marine invertebrates as bioindicators, creating tools that enable the early detection of environmental changes and providing data crucial for sustainable marine management.These projects offer innovative methodologies and insights into how marine ecosystems and their inhabitants respond to environmental stressors. They provide valuable knowledge for conservation efforts and marine resource management, particularly in the face of climate change, pollution, and habitat degradation. By improving our understanding of ecosystem resilience and bioindicators, these projects contribute significantly to shaping future strategies for preserving marine biodiversity and sustaining the services marine ecosystems provide to society.In addition to the previously mentioned projects, other significant ANR-funded projects, including Diplodevo, Annelivertebr, METAMERE, ISOBAR, MEDUSEVO, Echinodal, and DRIVE, are expanding the understanding of how marine invertebrates respond to global environmental changes. These projects provide innovative insights into species adaptation, stress tolerance, and evolutionary processes.These projects enhance the overall understanding of ecosystem responses to global change, offering valuable tools and methodologies for developing effective marine management strategies. This research is essential for preserving marine biodiversity and ensuring sustainable ecosystems in a rapidly changing world.

2.2. Biotechnology and biomedical issues

ANR-funded research has explored the potential of marine invertebrates for producing biomaterials with applications in medicine, biotechnology, and environmental sustainability. Marine invertebrates offer unique bioactive compounds, biopolymers, and biominerals that can be used in a range of biomedical applications, from wound healing to drug delivery systems. ANR-funded research into marine invertebrates has significantly advanced the fields of biotechnology and biomedicine. Projects like Annelides, LIFEGRAFT, CONOTAX, and HEMO2PERF have demonstrated how marine species can provide valuable biomaterials, bioactive compounds, and biomimetic technologies for a variety of medical applications, ranging from drug delivery to tissue regeneration. These studies highlight the potential of marine invertebrates in developing sustainable, biodegradable alternatives to synthetic materials, enhancing the future of regenerative medicine and biomaterial innovation. The integration of marine invertebrates into biomedical research also offers promising solutions to many pressing medical and environmental challenges, paving the way for more sustainable and effective medical technologies.

2.3. Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities

including one para on each of these specific aspects

• Links or contribution to human societies (economical, cultural aspects, adaptation, evolution of uses, etc.)
• Methodological breakthrough

3. Cutting edge research and links to society.

France's ANR-funded projects have made significant contributions to the understanding of macrozoobenthos and their roles in coastal ecosystems, with far-reaching implications for science, policy, and coastal communities.

3.1. Links to Human Societies

These projects are essential for supporting coastal communities, which rely on healthy marine ecosystems for fisheries, tourism, and other industries. By examining how marine invertebrates influence nutrient cycling, sediment stabilization, and food webs, projects like CHorMedFin offer valuable insights into the ecological services these organisms provide. This research helps communities adapt to climate change, pollution, and habitat loss, facilitating sustainable resource management practices that ensure long-term economic stability for industries like fisheries and tourism.

3.2. Methodological Breakthroughs

The research has introduced innovative methodologies, particularly in the use of bioindicators for detecting environmental stress. Projects such as BIONECAL are developing tools that enable early detection of pollution and habitat degradation, which can trigger timely conservation efforts. Additionally, projects like METAMERE and ISOBAR focus on predictive modeling to better understand how marine species respond to stressors like temperature rise, acidification, and pollution, improving environmental monitoring and adaptive management. These breakthroughs help scientists and policy-makers devise strategies for mitigating the effects of global change on marine ecosystems.

3.3. Impact on Science Policy

These projects directly inform science policy by providing essential data to guide marine conservation efforts. Research from projects like AGEsyMar and Echinodal contributes to policies that prioritize species resilience and ecosystem stability, promoting sustainable management practices under international frameworks such as the Marine Strategy Framework Directive (MSFD). The findings assist in shaping policies that protect marine biodiversity and ecosystem services, ensuring the sustainability of marine resources for future generations.

3.4. Innovation for Private Enterprises

The research also fosters innovation in private enterprises such as fisheries and aquaculture. By improving understanding of species’ resilience to environmental stress, businesses can implement sustainable practices and resource-efficient strategies. For instance, tools like bioindicators help companies track ecosystem health, enabling them to minimize their environmental impact and adapt their operations to changing conditions, ensuring long-term profitability.

3.5. Biotechnology and Biomedical Issues

ANR-funded research has explored the potential of marine invertebrates in biomedicine and biotechnology, offering promising solutions for a range of medical applications. Marine species provide bioactive compounds, biopolymers, and biominerals with diverse uses in drug delivery, wound healing, and tissue regeneration. Projects such as Annelides, LIFEGRAFT, CONOTAX, and HEMO2PERF demonstrate how marine-derived materials can replace synthetic, non-biodegradable substances. These innovations hold promise for regenerative medicine, offering sustainable alternatives that are both effective and environmentally friendly. Research into marine biomaterials supports the development of biodegradable medical devices and drug delivery systems, advancing biotechnology in environmentally responsible ways.

3.6. Conclusion

In conclusion, the ANR-funded projects offer valuable insights for sustainable coastal ecosystem management and biomedical advancements. These projects benefit coastal communities, private enterprises, and scientific fields by enhancing marine resource management, improving biodiversity conservation, and advancing biotechnology. By fostering innovations in environmental monitoring, bioindicators, and biomaterials, these projects contribute to building a more sustainable future for both marine ecosystems and society.

4. Research perspectives Despite significant progress in ANR-funded research on macrozoobenthos and marine ecosystems, there are still several knowledge gaps and barriers that need to be addressed for better management and understanding of coastal environments, particularly under the pressures of global change.

4.1. Carbon Sequestration in Bioindicators

One of the key areas that require further exploration is the role of marine invertebrates in carbon sequestration. While it’s known that macrozoobenthos contribute to blue carbon storage through processes like sediment stabilization, there is a need for bioindicators that can track and quantify carbon stocks in coastal ecosystems. This would enhance monitoring and help in understanding the broader role of marine ecosystems in climate change mitigation.

4.2. Upscaling and Regionalizing Research

Current research on macrozoobenthos often focuses on local or small-scale studies, which limits the applicability of findings at broader regional or global scales. Seascape ecology presents an opportunity to upscale research and understand how different coastal habitats interact across larger landscapes. This will help in understanding ecosystem connectivity and resilience across regions, informing marine spatial planning and ecosystem-based management practices.

4.3. Modeling Ecosystem Functioning

Understanding the functioning of entire ecosystems remains a challenge. Most models tend to focus on individual species or limited interactions, while ecosystems are much more complex. There is a need for integrated ecosystem models that take into account multiple species interactions, nutrient cycling, sediment stabilization, and other ecological services provided by macrozoobenthos in interaction with other all other compartments of marine ecosystems and interactions with atmosphere and catchments; thus, scaling towards holistic approaches. These models should also consider biotic and abiotic factors under changing environmental conditions.

4.4. Species Resilience and Adaptive Capacity

Further research is needed to understand the resilience of species to stressors such as climate change, pollution, and habitat degradation. Investigating the adaptive capacity of marine invertebrates, including their genetic and epigenetic responses, will help predict how species can cope with ongoing and future environmental changes. One of the key pressures threatening marine ecosystems, including macrozoobenthos is undoubtedly the effect of increasing inputs of organic and metallic pollutants, both in terms of diversity and abundance.

4.5. Integrating Socioeconomic Aspects

There is a need for greater integration of socioeconomic factors in marine ecosystem research. Understanding the human impact on coastal ecosystems, including the value of marine resources for industries like fisheries and tourism, is essential for developing sustainable management practices and policy strategies that balance environmental and economic needs.

4.6. Technological Advances

Developing and integrating new technologies, such as remote sensing, sensor networks, and big data, for real-time monitoring of marine ecosystems will improve environmental management and help track the health of marine habitats, providing the necessary data to make informed decisions.

In conclusion, addressing these gaps and overcoming barriers will enhance our ability to manage coastal ecosystems effectively and sustainably, especially in the face of global environmental challenges.

Deep sea ecosystems - Biology/Ecology of deep-sea communities and Biology, ecology and genomics of microorganisms and extremophiles

The discovery of deep-sea hydrothermal vents in 1977 revolutionized our understanding of the deep ocean, revealing remarkable biodiversity and microbial communities essential to their ecological and biogeochemical functioning. 53 ANR projects have led to the discovery of new hydrothermal sites and hundreds of new species, while highlighting the potential impacts of deep-sea mining. They have also contributed to technological and scientific advances, such as the use of pressure maintenance devices and high-throughput sequencing, enabling a better understanding of molecular adaptations and host-microbe interactions. This work has directly influenced public policies and international negotiations for the conservation of these environments. Future research could focus on the development of innovative tools and phylogenomic approaches to address environmental challenges, such as climate change and biodiversity loss, or the exploitation of mineral resources while supporting sustainable management of marine resources.

Didier Jollivet: CNRS, Sb Roscoff, Stéphane Hourdez: CNRS, obs Banyuls, Cécile Fauvelot: IRD, Karine Alain : UBO, Anne GODFROY: Ifremer, Marie-Anne Cambon: Ifremer

On Deep sea ecosystems there is 2 synthesis papers The first one is dealing with the species communities and the second one with microorganisms

Biology/Ecology of deep-sea communities

Scientific background

The deep-sea was first explored by late 19^th century naturalist expeditions. The discovery of deep-sea hydrothermal vents in 1977 revolutionized our view of the deep sea and rekindled interest in this realm in general. Studies focused on the understanding of chemoautotrophic symbioses through the localization and molecular characterization of symbionts and the physiological understanding of their hosts to better describe these unique adaptations to a reduced, toxic and hypoxic environment (Felbeck et al. 1981, Stein et al. 1988, Childress 1995, Cavanaugh et al. 2006). The subsequent exploration of the deep ocean in the 1980s-90s revealed the extreme biological diversity of the seafloor, whether along ocean ridges, cold seep areas, seamounts, canyons associated with continental slopes with or without sunken woods, or the carcasses of large whales (Distel et al. 2000, Suess 2014, Brooke & Ross 2014, Smith et al. 2015, Rogers 2018). Although composed of highly specialized prokaryotes and metazoans, these communities are characterized by very high biomasses, which contrasted sharply with the abyssal plains, making them hotspots of biodiversity. Since the creation of the ANR, French teams have been actively involved in exploring these difficult-to-access biotopes, rapidly describing these deep-sea communities and gaining a better understanding of the dynamics of these new ecosystems. It is only very recently (in the last 10 years) that the studies carried out to better describe and understand the functioning of these ecosystems have taken on a much more applied aspect, in order to protect these particular faunas from the predicted threat of mining on the metal-rich habitats to which they belong to, and to propose a sustainable management of these environments (Van Dover et al. 2018, Niner et al. 2018, Gollner et al. 2021, Amon et al. 2022, Mathon et al. 2024).

Main Contributions of the French Communities through ANR (co)funding

Over the last 20 years, the funding of ANR deep-sea projects has led to the discovery of new hydrothermal sites such as Last Hope and (7°S and 14°S/EPR), Achatze1 and 2 (14°N/MAR), Mangatolo (Lau Basin) and La Scala (Woodlark Ridge) and the study of their associated communities (Jollivet et al. 2005, Fouquet et al. 2008, Boulard et al. 2022) as well as other chemosynthesis-based habitats such as cold seeps along the African continental margins (ANR CongoLobe - Bessette et al. 2017, Olu et al. 2017, ANR Deep-Oases - Ritt et al. 2011). This active exploration of ridges has led to the description of numerous new species, whether viruses, extremophilic prokaryotes, fungi, symbiotic or non-symbiotic invertebrates or vertebrates, during diving campaigns such as Biospeedo 2004 (EPR), Serpentine 2007, Momareto 2007 and BICOSE 2014, 2018, 2023 (MAR), or Chubacarc 2019 (BaBs) (Hourdez et al. 2006, Stöhr & Segonzac 2006, Nielsen et al. 2006, Shields & Segonzac 2007, Paxton & Morrineaux 2009, Morineaux et al. 2010, Birrien et al. 2011, Gorlas et al. 2012, Borda et al. 2013, Bray et al. 2014, Burgaud et al. 2014, Chen et al. 2024, submitted). In parallel, the community targeted a few areas such as the Lucky Strike vent field in order to monitor hydrothermal communities with ANR funds (ANR MOHTESIEM, ANR LuckyScales), and gain a better understanding of their temporal dynamics. In the specific case of the site Lucky Strike, this has led to set up the EMSO-Azores seafloor observatory, deployed in 2010. Since the ANR-funded project Deep-Oases, a major effort was also made to better understand the demographic history of vent populations and to assess the connectivity along and across the oceanic ridges of three oceans, the East Pacific Rise (ANR Deep-Oases), the Mid-Atlantic Ridge (ANR LuckyScales, PPR LifeDeeper) and the western Pacific back-arc basins (ANR Cerberus). More recently, similar works have been also conducted on other non-chemosynthetic ecosytems such as those encountered on seamounts and mesophotic reefs of the South West Pacific (ANR SEAMOUNTS, ANR DEEPHOPE). Most studies based on indirect methods, such as population genetics and larval dispersal modelling, have clearly demonstrated that long-distance dispersal is not sufficient to replenish and renew these populations inhabiting this highly fragmented ecosystems (rescue effect), as some species have limited dispersal capabilities, while others are blocked by physical dispersal barriers such as transform faults or microplates (Plouviez et al. 2009, 2010, 2013; Breusing et al. 2016, Tran Lu Y et al. 2022, 2025, Castel et al. 2023, Poitrimol et al. 2023, Diaz-Recio Lorenzo et al. 2023, 2024, Portanier et al. 2025, Vilcot et al. 2024). The ANR Congolobe also highlighted the importance of bathymetric barriers to the connectivity of nearby populations along the continental slope where the Congo deep-sea fan is located, despite the great potential of dispersal for some species (Hassan et al. 2023).

The numerous cruises - not funded but associated with the ANR projects - have also allowed the French community to understand the vent and seamount ecosystem functioning by promoting faunal comparisons at different spatial scales: from their spatial distribution (image and eDNA analyses) to their habitat characterization (chemical and thermal), and the adaptative physiology of various biological players, from micro-organisms to macro-fauna. The thermal and chemical tolerance and physiological requirements of some holobionts such as the polychaete Alvinella pompejana (ANR BALIST), and more recently the shrimp Rimicaris spp. (PPR LifeDeeper) have been investigated in vivo (on board in pressurized devices) at in situ pressures (Ravaux et al. 2003, 2013, Shillito et al. 2014). This has allowed the deep-sea biology community to acquire one of the only devices currently known to sample organisms without decompressing them between capture and onboard experimentation (the in situ sampler PERISCOP coupled to the BALIST pressure transfer system, Shillito et al. 2023). Whether it has been used on the Pompeii worm or the shrimp Rimicaris exoculata, numerous samples experimented under different thermochemical constraints have provided clues to gain a better understanding of their biology through omics approaches (Cottin et al. 2008, 2010, Boutet et al. 2009, Auguste et al. 2016). To this extent, a GIS Marine Genomics project (ANR AdaptAlvinStreS) offered, for the first time to sequence a complete transcriptome for the thermophilic worm Alvinella pompejana in order to better understand its molecular adaptations to high temperatures (Gagnière et al. 2010, Jollivet et al. 2012, Fontanillas et al. 2017), and then to allow the sequencing of its whole genome at the chromosome level (El Hilali et al. 2025). More recently, a tool for preserving various organisms in situ (FISH prototype) has been developed to study their physiology on the seafloor using the same approaches (PPR LifeDeeper). The study of symbioses was also the subject of integrated approaches ranging from histology to genomics for several targeted species (Alvinellid worms, Bathymodiolus mussels, Rimicaris shrimp and vesicomyid seep clams). Most physiological and genomic analyses done in ANR Deep-Oases, ANR LuckyScales, ANR CongoLobe, ANR Cerberus or the PPR LifeDeeper) focused on the molecular dialog between the host and its symbionts and how the host can take up and release toxic compounds (HS2, CO2, H2) to its bacterial cells to synthetize organic carbon using both enzymatic pathways and respiratory pigments (Sanchez et al. 2007, Halary et al. 2008, Duperron et al. 2009, Boutet et al. 2011, Decker et al. 2017) but also to cope with temperature, high metal concentrations, hypoxia and sulfidic waters (Bruneaux et al. 2008, Decelle et al. 2010, Projecto-Garcia et al. 2010, Decker et al. 2014, Le Layec & Hourdez 2021).

In the deep-sea, access to food is a very limiting factor for ecosystems. Far from the surface, photosynthesis is no longer possible and all food falls from the surface as marine snow, which amount decreases with depth. The exception are chemosynthesis-based ecosystems often found in hydrothermal vents, cold seeps and whale falls but other deep-sea ecosystems have been also investigated by ANR projects, suggesting that sulfide hydrogen, even at reduced concentrations, can still play a role in the establishment of the abyssal fauna. There were only few records of bacterial and wood fall mats where the presence of hydrogen sulfide at the wood surface should create a perfect niche for sulfide-oxidizing bacteria. Two projects investigated chemosynthetic features from river material rich in organic matter exported to deep-sea lobes of river deltas (ANR CongoLobe) and submarine canyons (ANR MICADO). Using amplicon and metagenomic sequencing combined with fluorescence in situ hybridization, Kalenitchenko et al. (2018) found that wood surface was first colonized by sulfide-oxidizing bacteria belonging to the Arcobacter genus after only 30 days of immersion. Subsequently, the number of sulfate reducers increased and the dominant Arcobacter phylotype changed. The ecological succession was reflected by a change in the metabolic potential of the community from chemolithoheterotrophs to potential chemolithoautotrophs, demonstrating that microorganisms alone could establish the chemical basis essential for the recruitment of a chemosynthetic fauna on deep-sea wood falls.

In ecology, the identification of the macro- and meiofauna has been assessed using both morphological and molecular approaches in several project (ANR Deep-Oases, ANR Cerberus, ANR LuckyScales, ANR SEAMOUNTS, ANR DEEPHOPE, ANR TFDeepEvo) to better characterize ,  and  diversities of vent communities in the Atlantic (Ivanenko et al. 2012, Alfaro-Lucas et al. 2020, 2024, Sarrazin et al. 2022), Eastern Pacific (Matabos et al. 2011) and Western Pacific (Poitrimol et al. in press) but also for African cold seeps (Ritt et al. 2011), the Pacific mesophotic reefs (Terrana et al. 2024, Pérez-Rosales et al. 2022), the deep-sea benthos in the South-Eastern Asia (Pante et al. 2015) or the Pacific seamounts (Vilcot et al. 2024, Baletaud et al. 2023). The genetic and functional diversity of microbial and fungal communities was also assessed using a combination of cultural and molecular approaches during the course of several ANR projects (ANR Deep-Oases, ANR LuckyScales, ANR CongoLobe or ANR MICADO, and, to a lesser extent, ANR Cerberus - Burgaud et al. 2009, Byrne et al. 2009a, 2009b, Crépeau et al. 2011, Fagervold et al. 2014, Bessette et al. 2017). In this context, the ANR projects MOHTESIEM and LuckyScales have allowed an integrated assessment of the spatio-temporal dynamics of the vent communities (mostly mussel beds) for the instrumented hydrothermal field at the Azores triple junction, following the recurrent Momarsat campaigns at the EMSO-Azores seafloor observatory. This effort provided a high-resolution cartography of the seafloor, bottom currents, earthquakes, vent habitats and communities for this specific area (Escartin et al. 2008, Dusunur et al. 2009, Chavagnac et al. 2018, Vic et al. 2018). The yearly monitoring of the Lucky Strike field and associated cartographies greatly improved the understanding of the role of abiotic factors (tectonism, fluid chemistry, currents) and biotic interactions on the biological rhythms and species composition of the vent communities and their evolution over time (Husson et al. 2017, Cuvelier et al. 2017, Alfaro-Lucas et al. 2020, Girard et al. 2020). The use of microbial community cultures in 'bioreactors' also provided new information about the influence of environmental parameters on the dynamics of thermophilic communities in active hydrothermal structures and their link with holobiont communities (Byrne et al. 2009a, Callac et al. 2015). Colonization and larval capture (SALSA) experiments carried out in situ in different chemosynthetic ecosystems also offered additional clues about species recruitment and their possible role in community resilience (Cuvelier et al. 2014, Zeppili et al. 2015 in ANR Deep-Oases, ANR LuckyScales and PPR LifeDeeper).

In 2023, the PPR Ocean & Climate LifeDeeper was set up for a more applied purpose in order to gain a better understanding of the potential resilience of the deep hydrothermal ecosystem of the low-spreading Mid-Atlantic Ridge to human impacts by carrying out geological and biological monitoring of the French mining exploration license area located between 21 and 26°N (800 kilometres of ridge). This project is intended to provide the International Seabed Authorities (ISA) with recommendations for the sustainable exploitation of polymetallic sulphide ores while protecting the associated fauna. It relies on the development of new vehicle such as the AUV Ulyx to (1) better understand the functioning of this rather ‘old’ geological system and the spatio-temporal dynamics of the associated vent communities, (2) assess the life cycle of holobionts and their connectivity and (3) define more clearly the microbe-based trophic web and the potential of organisms to sense vents and acclimate mining changes using experimental approaches. So far, to understanding of the symbiotic way of life of the vent shrimps at all ontogenic stages with numerous symbiotic partners in the cephalothorax and digestive tube (Guéganton et al. 2022, 2024, Methou et al. 2024), the LifeDeeper project has already produced maps of the distribution of active and inactive sites (such TAG Pelleter et al., 2024) and communities at the scale of active fields, taking into account the activity gradient, in order to clarify the notion of active vs. inactive site, which is involved in the drafting of the ISA Mining Code to decide what should be exploited. To this extent, one of the project partners was involved as an observer in the drafting of the BBNJ 'IGC5bis' treaty for the protection of deep-sea fauna, and in the international negotiation arenas at the UN (New York) and ISA (Kingston) headquarters for the drafting of the Mining Code.

Research perspectives

Over the last 20 years, the scientific community working in deep-sea biology has acquired an arsenal of prototypes that enable it to (1) search more effectively for new active sites (i.e. powerful acoustic methods for locating sites and plumes, high-resolution bathymetry, chemical mapping of deep-water layers (AUV Ulyx), (2) detect and map benthic habitats at large spatial scales using hyperspectral imagery with drones (ANR HypFoM) - such methodology having been recently used to survey cold-water coral reefs in the Bay of Biscay canyons - or (3) study organisms without sampling stress (more powerful samplers for ROVs and HOVs, and prototypes for hyperbaric transfer of organisms). These methodological developments need to be continued and extended to better meet societal needs while protecting the deep ocean. In the near future, we especially need to develop a larger number of in situ analysers, in particular to be able to sample the water column (DeepSea’Nnovation for eDNA and larvae samplers), or on-board mass spectrometers to characterize both water chemistry and the proteome/metabolome of target species under their living conditions. These new tools will be essential for carrying out integrated studies combining in situ experiments with the chemical characterisation of habitats and the preservation and/or in situ characterization of samples for omics perspectives, by coupling imagery and sequence data for species identification.

Biology, ecology and genomics of microorganisms and extremophiles

Didier Jollivet: CNRS, Sb Roscoff, Stéphane Hourdez: CNRS, obs Banyuls, Cécile Fauvelot: IRD, Karine Alain : UBO, Anne GODFROY: Ifremer, Marie-Anne Cambon: Ifremer

Scientific background

The microbial world and virosphere are extremely vast and extraordinarily diverse on our planet, as it is the case at the oceans bottom (Suttle, 2005; Flemming and Wuertz, 2019). This is largely due to the fact that prokaryotic life has dominated most of our planet's evolutionary history, evolving to occupy virtually every available environmental niche and every province of the ocean floor, including those characterized by extreme physico-chemical parameters (Merino et al., 2019). To colonize the most extreme environments (Shu and Huang, 2022), microorganisms have developed unprecedented capacities for adaptation. On a global scale, microbial communities help maintaining the balance and functions of ecosystems, by participating in the flow of matter and energy, recycling elements and remineralizing organic matter. They also play a role in the resilience of ecosystems, including marine ecosystems, to human disturbance and climate change (Cavicchioli et al., 2019). So far, despite of their importance in an array of ecological processes, as-yet-uncultivated taxa account for ≥ 80% of the phylogenetic diversity of bacteria and archaea (Steen et al., 2019; Nayfach et al., 2021). Our knowledge of archaea and of bacterial candidate phyla radiation remains limited while they obviously mediate an array of ecological processes (Baker et al., 2020). Some of them probably possess non-identified physiological properties. Viruses play fundamental roles in ecology and evolution (Suttle, 2007; Roux et al., 2016). In recent years, omics approaches have increased the known diversity of viruses by more than an order of magnitude, revealing many new groups that are only slightly related to those already known, as well as extremely abundant new viral groups, representing an enormous reservoir of largely untapped genetic diversity that is far from unveiling all its secrets (Koonin et al., 2024).

Main Contributions of the French Communities through ANR co-funding

Over the last 20 years, the ANR has funded projects aimed at documenting the mechanisms that may have led to the emergence of life, and providing elements for understanding how the inert gave way to the living. For example, the French community investigated in detail the condensation, adsorption and polymerization of amino acids and nucleotides under a variety of thermodynamic conditions, with a particular focus on high-temperature conditions and hydrothermal environments, in order to identify the thermodynamic conditions and minerals conducive to the assembly of the building blocks of life into biomolecules, in the context of the origin of life (Prebiom- ANR-15-CE31-0010; Hao et al., 2018a Montagnac et al., 2021). They demonstrate, for example, that the interactions between nucleotides and mineral surfaces depend very largely on the chemistry of the aqueous solution, and in particular on the pH, concentration and nature of the divalent cations (Mignon et al., 2020) and that transition metals play a key role in nucleotide adsorption, especially when the pH is alkaline (Hao et al., 2018b). Analyses have also shown that polymerization of the simplest amino acid occurs spontaneously under hydrothermal conditions, with the majority of linear oligomers being formed (Pedreira-Segade et al., 2019; Sakhno et al., 2019), demonstrating the feasibility of one of the chemical reactions that may have led to the appearance of life on earth.

Over the past twenty years, ANR research has also helped reveal the extent of microbial diversity in the deep ocean (EVOLDEEP- ANR-08-GENM-0024; MISD- ANR-22-CE02-0001; IRON2MI-ANR-22-CE01-0013; LIFEDEEPER ANR-22-POCE-0007 and France 2030 Mission 1 ANR-22-MAFM-0001), and contributed to a better understanding of the microbial metabolic pathways (MISD- ANR-22-CE02-0001; IRON2MI-ANR-22-CE01-0013; LIFEDEEPER ANR-22-POCE-0007) and of the evolutionary history of microorganisms (EVOLDEEP- ANR-08-GENM-0024). Using metagenomic approaches, new lineages of bacteria, archaea and eukaryotes, often diverging from known cultured lineages, have been revealed in deep-sea marine picoplankton (Quaiser et al., 2011; Bachy et al., 2013). Work by the French scientific community has contributed to the detection of new metabolic pathways in the deep-sea (Deep-Oases - ANR-06-BDIV-000, Byrne et al., 2009) and to demonstrate the involvement of unsuspected prokaryotic groups in little-documented metabolic reactions such as the disproportionation of sulfur compounds (Wang et al., 2022; MISD- ANR-22-CE02-0001), or the oxidation and reduction of iron (IRON2MI-ANR-22-CE01-0013), and to decipher the metabolic pathways at work (Yvenou et al., submitted), thus extending our knowledge of the functioning of deep-sea biogeochemical cycles. Specific lineages of planktonic archaea were detected and helped to produce a better global phylogeny for archaea, using the newly available genomes and increasing the list of conserved genes available to study phylogeny on a large evolutionary scale (Spang et al., 2010; Brochier-Armanet et al., 2011). This work has also revealed new links between archaea and eukaryotes (Brochier-Armanet et al., 2011) and proposed a parsimonious evolutionary scenario according to which sulfur disproportionation could be a very ancient metabolism first appearing in a common ancestor of Desulfobacterota, Nitrospirota and Acidobacteriota in the Paleoarchean (Novak et al., submitted).

Several studies also documented interaction between prokaryotes and minerals (HYPERBIOMIN – ANR-20-CE02-0001; MISD- ANR-22-CE02-0001; IRON2MI-ANR-22-CE01-0013; LIFEDEEPER ANR-22-POCE-0007). Certain microorganisms in deep-sea hydrothermal vents have been shown to promote mineral formation, and the underlying mechanisms by which hyperthermophilic archaea contribute to the mineralogy and biogeochemistry of sulfide-rich hydrothermal vents have been investigated (Gorlas et al., 2022; Truong et al., 2023; Yvenou et al., submitted). An autecological approach using gas-lift bioreactors was also carried out to simulate in situ alteration and mineralization processes at the redox interface of an active hydrothermal vent in contact with the surrounding seawater and in the presence of complex natural microbial communities, at different temperature., It revealed that toxic compounds are released at low temperature under oxic conditions by dissolution of freshly broken mineral phases, which is particularly informative in the context of the future exploitation of hydrothermal polymetallic sulfide mining resources (Fuster et al., in preparation, LIFEDEEPER ANR-22-POCE-0007).

In addition, some studies (Genoarchea- ANR-05-BLAN-0408) have revealed a wide diversity of mobile genetic elements (plasmids) in the Euryarchaeota (over 200 newly isolated hydrothermal strains). The plasmids were sequenced and their annotation highlighted the presence of new genes involved in DNA replication and repair processes (Soler et al, 2010). The sequencing and the analysis of the genome of the first euryarchaeota virus PAV1, (Geslin et al., 2007), as well as new technical developments, have paved the way for the description of new viruses from hyperthermophilic Archaea (Gorlas et al, 2012).

The ANR also funded projects aimed at understanding how life maintains itself in extreme physico-chemical conditions, and at describing adaptations implemented at the limits of life. For example, work has resulted in the isolation of the only known obligate piezophilic hyperthermophilic archaeon from a deep-sea hydrothermal vent, Pyrococcus yayanosii (Deep-Oases - ANR-06-BDIV-0005; Birrien et al., 2011), as well as the piezophilic hyperthermophilic strain Thermococcus piezophilus (Dalmasso et al., 2016), which possesses the widest range of hydrostatic pressures for growth ever described for a microorganism, representing excellent models for studying adaptation to high pressures (Moalic et al., 2021). An innovative methodology, combining genomic and proteomic approaches enabled to understand the "passive / preventive" (structuring of the genetic heritage, metabolic response) and "active / curative" mechanisms (detoxification, DNA repair) of radiotolerance in the hydrothermal vent archaeon Thermococcus gammatolerans, especially after stresses that strongly damage its genetic heritage (Gammatolerans - ANR-12-BSV6-0012; Yang et al, 2015 ; Alpha-Bazin et al, 2021). Furthermore, the use of integrative structural approaches in the framework of the study of the proteasome in Archaea (a simplified prototype of the eukaryotic proteasome) allowed to uncover the basis of an ancestral mechanism that regulates the activity of a complex protein destruction machinery (ARCHELYSE- ANR-12BSV8-0019; Appolaire et al, 21013; Appolaire et al, 2014). As in eukaryotes, the proteasome dysfunction is involved in aging and degenerative diseases, this system could be a target for the treatment of numerous diseases and the effects of aging on human cells.

Finally, several methodological developments are in progress to gain fundamental insights into the biodiversity of prokaryotes and the dynamics of hydrothermal ecosystems. These developments cover high-pressure microbiology, environmental sampling and recovery under in situ condition, miniaturized pressurized instrumentation with rapid screening (microfluidics at high pressure and high temperature), advanced transparent tools for in situ characterization, bioreactor platforms and numerical modeling (HOT-DOG - ANR-22-CE02-0017, LIFEDEEPER ANR-22-POCE-0007; France 2030 Mission 1 ANR-22-MAFM-0001).

Research perspectives

In the future, scientific research priorities will be to (i) study the little-known branches of the prokaryote and virus tree, and improve phylogenomic approaches to trace the evolutionary history of living organisms; (ii) study the new functions and new metabolisms of marine microorganisms and viruses and their responses to adapt to their environment, which could lead to numerous biotechnological applications; (ii) to pursue fundamental research in biology-ecology-evolution, reinforcing interdisciplinarity to provide predictions in a context of environmental change and provide scientific solutions to the complex and urgent challenges we face; (iii) to facilitate the transition from knowledge to action in order to find solutions to environmental crises and enlighten decision-makers.

GEOSCIENCES : Sedimentology, Géohazards, Coastal dynamics

Population growth in coastal areas increases their vulnerability to marine and geological hazards, exacerbated by climate change. 110 projects supported by the ANR have led to major advances in different sectors: modeling of sediment dynamics, monitoring of underwater risks (earthquakes, tsunamis), and assessment of coastal vulnerability. By combining physical, socio-economic data, and innovative tools (AI, sensors, satellite imagery), this research strengthens the alert and adaptation capacity of coastal territories, laying the foundations for more resilient management in the face of climatic and geological pressures.

Gilles Lericolais : Ifremer/SG Mer, Bruno Castelle : Univ Bordeaux

1) Scientific background:

The Earth’s population has reached 8.2 billion people in 2024, of whom more than 2 billion live near the coast and could reach 2.9 billion by 2050 according to the United Nations population estimates and projections report, 2024. This high population density along the coasts and the expected growth of complex critical infrastructure and ocean services in coastal regions lead to increasing levels of exposure and vulnerability to marine geohazards. Indeed, these coastal areas are subject to risks that can lead to severe impacts due to the high concentration of people and assets in exposed locations. In particular, climate-induced sea-level rise will exacerbate these risks during the 21st century.

A geohazard is a geological condition that represents – or has the potential to develop – a situation leading to uncontrolled damage or risk. The United Nations Office for Disaster Risk Reduction (UNDRR) defines intensive risk as disaster risk associated with low-probability, high-impact events, while extensive risk is disaster risk associated with high-probability, low-impact events. Dangerous marine geological events can occur at any time and the scientific community, the maritime industry and government agencies are called upon to cooperate to better understand and monitor the processes involved in order to mitigate the unpredictable damage that results.

The marine geoscience projects funded by ANR, whether for the understanding of sedimentary processes (sedimentary hydrodynamics) or on the understanding of geological risks, have increased knowledge on marine geohazards and therefore shed light on the measures needed to reduce our exposure and vulnerability to such events. This corresponds to one of the societal objectives of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), which advocates a safe ocean where lives and livelihoods are protected from ocean-related hazards.

Coastal regions are facing increasing risks from natural hazards such as coastal erosion, flooding, and submersion, which are being intensified by climate change. Rising sea levels, along with changes in storm frequency and intensity, pose serious threats to coastal communities, infrastructure, and ecosystems. Understanding, modelling, and predicting coastal evolution is therefore essential to developing effective adaptation strategies and mitigating future risks. Coastal change is, however, a complex problem driven by multiple nonlinear processes interacting with each other on a wide range of time and space scales. At small scales, waves, tides, and currents move the sediment through different modes and reshape the seabed. At larger scales, extreme events, sea-level fluctuations, and human interventions influence coastal evolution over days, decades to centuries. Because these nonlinear processes and feedback mechanisms, predicting future changes remains a major scientific challenge. Progress requires combining small-scale physical process studies, through laboratory experiments, upscaling and process-based modelling, with large-scale approaches such as reduced-complexity models and satellite remote sensing to track long-term shoreline change an large spatial scales. The accuracy of the models and remote sensing algorithms also heavily rely on high-quality, detailed, ground-truth data through intensive field measurements and long-term monitoring program.

Over the past 20 years, major scientific advances through ANR-funded projects have improved our understanding of sediment transport, feedback mechanisms, and the impacts of extreme events. Such processes can now be transformed into parametrisation into larger-scale models, which have been used in other ANR-funded projects to explore future changes, including under the effects of climate change. Satellite remote sensing also transformed the, large-scale multi-decadal, coastal science from a data poor to a data rich field, recently making possible data assimilation, application of machine and deep learning techniques and shoreline change assessments at global scale. Although limitations and knowledge gaps remain, these developments have led to better long-term projections and uncertainty assessments, providing valuable tools for engineers, policymakers, and coastal managers.

2) Main Contributions of the French Communities through ANR co-funding.

2-1 Scientific progress; cutting edge science

Today, the expansion of economic activities is driven by a combination of population growth, rising incomes, diminishing natural resources, responses to climate change and pioneering technologies. The “blue economy” thus encompasses established ocean industries as well as emerging and developing activities that are reshaping and diversifying maritime industries (OECD, 2016). These activities include offshore renewable energy, communications, maritime cruise tourism, offshore aquaculture, marine biotechnology and bioprospecting, seabed mining, aggregate extraction, ocean monitoring, control and maritime surveillance. Other activities for which there are not yet established markets include carbon sequestration, coastal protection, waste disposal and biodiversity conservation and restoration.

ANR participates in the European Partnership for a Sustainable Blue Economy. The objective of this Partnership is to accelerate the transformation towards a climate-neutral, sustainable, productive and competitive blue economy. This is to restore the health, resilience and services provided to ocean populations by promoting climate-neutral, sustainable and productive economic activity. Such objectives cannot reach without encompassing geohazards.

Marine geohazards related to seabed processes include earthquakes (the most destructive earthquakes to affect humanity have occurred at sea), landslides, volcanic eruptions and associated tsunamis. Marine geohazards can also include rapid changes on the seabed such as the migration of submarine dunes (bedforms), seabed liquefaction and gas migration that can lead to local overpressure in sediments and potential submarine landslides. To date, most geohazards occurring on the seabed are unknown, poorly characterized and difficult to monitor (with current technology).

Hazards are intimately linked to risk. A risk is the probability that an event resulting in loss of life, injury, or destruction or damage to property could occur to a system, society, or community within a given time frame. A risk is therefore determined as the product of three factors: hazard, i.e. the probability that a given event will occur within a given time; exposure, i.e. the human lives and the quantity and value of property exposed to the hazardous event; and vulnerability, i.e. the amount of damage the event will cause to the exposed property. The main marine geological hazards are coastal erosion, seawater intrusion, earthquakes, submarine landslides, subsidence, tsunamis, dissociation of natural gas hydrates, seabed sand waves, shallow gas, overpressure strata, gas chimneys, mud volcanoes, and mud diapirism.

The advancement of deep-sea exploration activities, uncertainties about the consequences of climate change, recent global catastrophic events (e.g. the 2004 Indian Ocean and 2011 Japanese tsunamis) correlated with the increase in human population density in coastal regions of the world are responsible for the increased importance and awareness related to marine geohazard research. Specific threats to society related to marine geohazards are the loss of land near the coast, the devastation of coastal areas by tidal waves generated by landslides and the destruction of marine facilities, (e.g. communication cables, pipelines).
ANR funded projects collectively bridge gaps between fundamental processes and practical applications, from small-scale sediment transport in turbulent flows to large-scale coastal evolution under varying climatic scenarios. A major scientific breakthrough in sediment transport has come from projects like SHEET-FLOW, WEST, 2-phaseSEDEXPn, and RUPTURE, which have refined our understanding of sediment dynamics under high-energy conditions. These projects focused on the complex fluid-particle and particle-particle interactions that occur during sediment transport, particularly under energetic flows and during extreme events like storms and hurricanes. SHEET-FLOW, for example, has advanced two-phase sediment transport models, incorporating acoustic instrumentation to measure velocity and sediment concentration at turbulent scales, revealing the key role of sheet flows in sediment dynamics. Similarly, WEST has provided new insight into sediment transport during recovery phases, focusing on accretion and bed slope adjustments after storms, with has implications for coastal resilience. The 2-phaseSEDEXPn and RUPTURE projects further refine our understanding of turbulence-induced sediment transport, using new ultrasound and hydro-acoustic techniques to measure sediment fluxes in turbulent flows. These advancements have significantly improved sediment transport models, allowing for more accurate predictions of bedform evolution and coastal erosion.

Beyond sediment transport, several projects have focused on the long-term evolution of coastlines, particularly in response to climate change and storm events. Projects like VULSACO and SHORMOSAT offer a broader understanding of coastal systems and their vulnerability to climate change. VULSACO, for instance, has developed vulnerability models for sandy coastal areas, assessing both short-term storm impacts and long-term erosion trends under future climate scenarios. The integration of socio-economic factors into these models has provided a more holistic view of coastal vulnerability. COASTVAR, focusing on tropical coastlines in West Africa and Vietnam, has employed innovative observational tools like drones and video imagery, as well as 3D coupled models, to study wave-induced circulation and surf-shelf exchanges. This research has significantly advanced our understanding of the hydrodynamics and sedimentary processes in these regions, which had received little attention by the scientific community so far. SONO has tackled the key role of beach-dune systems in coastal resilience. By studying dune evolution in response to human management and climate change, SONO has integrated geomorphological, ecological, and hydrodynamic data to develop a new coastal dune modelling framework. This research was used to improve coastal management practices in southwest France and beyond, especially in areas where dunes serve as vital buffers against storm surges and erosion. SHORMOSAT has made breakthrough advancements in large-scale shoreline change modelling by integrating satellite-derived data and improving shoreline models. This project has focused on understanding how shoreline changes are influenced by factors such as sea-level rise, wave conditions, coastal structures, and by addressing projections uncertainties.

Together, these projects highlight a significant advancement in our understanding of coastal dynamics, emphasizing the interactions between natural processes and human influences. They have not only expanded the fundamental scientific knowledge of coastal systems but have also provided practical tools for coastal zone management and planning. For example, the integration of numerical models with satellite observations in SHORMOSAT and GLOBCOASTS offers unprecedented opportunities for global coastal monitoring, while the development and/or improvement of process-based models in COASTVAR, CHIPO or KUN-SHEN helps anticipate future changes in coastal systems under various climatic conditions. Overall, these projects contribute to a more integrated understanding of coastal systems, particularly in the context of climate change

2-2 Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities

The ANR projects' results address Challenge 6 (Improve multi-hazard early warning services for all ocean and coastal hazards of geophysical, ecological, biological, meteorological, climatic and anthropogenic origins, and integrate community preparedness and resilience) of the UN Decade of Ocean Science for Sustainable Development (2021-2030). This is realised by presenting how to increase public authorities’ awareness of marine geohazards and frame marine geohazards in administrative management rules.

For a safe and sustainable use of the seabed, public authorities and policy makers responsible for coastal and maritime management and planning must be aware of the importance of marine geohazards. National and local government agencies responsible for coastal communities and infrastructure are well aware of land-based natural hazards, but the potential of offshore threats remains largely unknown. The reasons for this lack of attention are: 1) technologies to highlight marine geohazards are relatively new; and 2) until a decade ago, the use of the seabed was limited and there was little need to manage submerged territories. Similarly, public awareness of natural marine hazards is often low, even though the two very large tsunamis that hit Asia in 2004 (Indonesia) and 2011 (Japan) demonstrated how real marine geohazards can be and that they are not “a thing of the past”. It is therefore necessary that marine geohazards be included as natural hazards in all policies related to risk mitigation and land management.

By blending fundamental research on coastal dynamics with practical tools for coastal management and forecasting, ANR-funded projects provide a comprehensive approach to addressing the challenges faced by coastal communities worldwide. With rising concerns over climate change, coastal areas, particularly sandy beaches, are highly vulnerable to erosion, submersion, and extreme weather events. Projects like VULSACO, SHORMOSAT and COASTVAR have advanced the understanding of how human activities, such as urbanization and tourism, exacerbate these vulnerabilities. By integrating socio-economic factors into physical models, these projects are helping coastal managers anticipate the impacts of future storms and sea-level rise, informing adaptation strategies that are both scientifically sound and socially relevant. The integration of public and private stakeholders has also fostered collaborative solutions for beach restoration, and for instance coastal dune management in SONO contributing to more resilient coastal ecosystems. Furthermore, the development and application of advanced monitoring systems like drones, UAV surveys, and satellite imagery, as seen in GLOBCOASTS and SHORMOSAT, can now provide unprecedented data for making informed decisions.

Methodological breakthrough

The lack of an appropriate policy framework to guide the management of marine geohazards is a specific obstacle to the management of these risks. Due to the novelty of tools for detecting and quantifying marine geohazards, national and international legislation is often poorly defined. Local land management agencies should be required to translate scientific knowledge on marine geohazards into regulatory guidelines or restrictions to be applied, and to co-develop with civil protection agencies (or other similar bodies) emergency measures.

There is a need to integrate marine monitoring infrastructures such as the European Multidisciplinary Seabed and Water Column Observatory (EMSO) and all other long-term monitoring of high-risk areas with seabed mapping and geohazard research.

Permanent seafloor observatories continuously collect environmental data at a fixed location, while mapping seafloor geohazard characteristics will provide spatially continuous but time-accurate data. Since seismic, acoustic and chemical signals from the seafloor can travel tens of kilometres, a comparison between detailed geohazard characteristic maps and observatory signals will allow us to understand the evolution of geohazard phenomena such as mass loss, volcanic eruptions, fault activity and gravitational flows over time, and potentially to define precursors.

New technologies should facilitate long-term in situ monitoring combined with geohazard studies in surrounding regions to identify long-range signals. Dedicated marine geohazard field laboratories should be established at targeted sites to concentrate research, facilities and in situ modelling.

The projects have also introduced methodological breakthroughs that enhance our ability to predict, model, and manage coastal dynamics. CHIPO, for instance, has innovated by combining longshore and cross-shore processes into unified models, filling a gap in the study of beach morphodynamics. By initiating the development of a new generation of reduced-complexity shoreline models, complementary to traditional process-based models, CHIPO reduced simulation errors while providing cost-effective solutions for long-term shoreline predictions. Similarly, SHEET-FLOW and RUPTURE have made advancements in sediment transport modelling by resolving two-phase flow interactions, which are essential for accurately simulating sediment fluxes during turbulent conditions. The use of cutting-edge hydro-acoustic techniques and advanced sediment transport models in RUPTURE represents a significant leap in understanding fine-scale sediment transport dynamics. Additionally, the innovative data assimilation techniques developed in SHORMOSAT and GLOBCOASTS are setting new standards for global coastal monitoring, enabling more precise predictions of shoreline change and coastal evolution. These methodological advancements not only allowed enhanced scientific knowledge, but also provide practical tools and data for the scientist community as well as coastal managers.

3) Research perspectives.

The perspectives to be considered today for moving towards a more in-depth assessment of marine risks involve scientific research on marine geohazards, which is essential for understanding the characteristics, magnitude and recurrence intervals of events (i.e. how often they occur in the same place). For example, the magnitude of an earthquake that a fault can generate depends on its geometric characteristics and its relationship with deeply rooted active geological structures; the tsunamigenic potential of a volcano depends on the explosiveness of its past eruption(s) and the stability of its flanks. Sedimentary movements linked to ocean currents or sea-level rise generate risks on marine or coastal infrastructures. The magnitude of the geohazard is very different if an area is subject to storms or landslides every year, once every ten years, once a century or once a millennium. Scientific studies on marine geohazards therefore focus on: 1) the identification of past geohazard events and the assessment of their frequency, as well as 2) the monitoring of current active processes that may evolve into a marine geohazard.

Recently, the development of mathematical models for hazard definition, geotechnical measurements, field and laboratory data collection, and event dating has gradually increased. These tools can be applied to understand the formation and mechanisms of marine geohazards and their consequences, but also to develop warning systems before these disasters.

A challenge for future coastal research is improving the integration of multiple data sources and models to enhance predictions and better understand coastal change. Combining satellite observations with machine learning and deep learning algorithms represents a promising direction for refining our ability to forecast future coastal changes on a wide range of time and space scales. Such integration could improve understanding of coastal dynamics over large spatial scales, accounting for both natural variability and human influence, and offer more reliable projections of coastal evolution. Another issue in advancing coastal research is the quantification of uncertainties in model outputs. While progress has been made in the frame of recent ANR-funded projects, there remains a need to better understand the sources of uncertainty and how these propagate through the models. Future research should focus on improving uncertainty quantification methods, particularly in relation to the effects of climate change and human activities, to tackle where uncertainties can be reduced, and to generate more accurate predictions. The integration of human influences, such as coastal structures, beach nourishment, and land use, as well as biotic-abiotic interactions in certain environments, remains underexplored. Another important avenue for future research is the development of innovative, cost-effective monitoring and modelling tool, to enhance real-time monitoring of coastal systems, allowing for rapid response to extreme events and improving long-term coastal planning

MARINE RENEWABLE ENERGIES

Marine energies include two categories: bioenergy (algae, phytoplankton) and marine renewable energies (especially offshore wind), both of which play a central role in the energy transition. 21 ANR projects have mainly supported the study of the development of offshore wind and its global impact. Major advances in the reliability of infrastructures, their environmental integration, and maritime space planning have thus been made. This research promotes industrial innovation, international competitiveness, and the coexistence between energies, biodiversity, and human activities. Offshore wind, the only mature large-scale technology, still requires efforts to better understand its ecological and social impacts, strengthen its acceptability by the population, and integrate the effects of climate change.

Jean-Francois Filipot : France Energie Marine

1. Scientific background

Marine energies are at very different stages of maturity, with offshore wind being the only technology capable of making a massive contribution to energy mix.

This technology still faces a number of challenges that will require advances in research in the following areas:

Characterisation of wind energy production and weather conditions:

Knowledge of wind energy production is a critical input for defining wake models between machines. These two issues need to be tackled in order to refine our knowledge of offshore wind and the air-sea interactions or flows that affect wind profiles, interactions that also affect the development of wind turbine wakes.

These subjects will be of growing interest with the deployment of increasingly large turbines, interacting with the atmospheric boundary layer, coupled with farms that are also more massive, whose wakes could disturb farms located downwind.

At the same time, knowledge of atmospheric turbulence at sea is another key factor, influencing the intensity and extent of wakes, as well as turbine sizing. This is a particularly important issue for sites at great depths (typical of floating wind farms) where no measuring masts are available. In this case, measurements have to be taken from lidars deployed on buoys, a constraint that significantly complicates the exploitation of the backscattered signal and constitutes a research topic in its own right.

Defining the extreme wind, wave and current conditions generated by mid-latitude storms and tropical cyclones is a critical issue for the design of offshore wind turbines. In particular, these conditions require observation systems capable of withstanding the elements. Satellite measurements are extremely valuable in this context, as the sensors are not subjected to storms, but indirect measurements can still be improved to refine our knowledge of extreme winds and waves.

Among extreme waves, breaking waves represent a potential danger for offshore wind turbines: they can damage the foundations and excite the modes of the tower and endanger sensitive components of the nacelle. Research efforts are essential to correctly qualify the loads they induce on structures by estimating the statistics for the occurrence and severity of these events at sea and developing numerical and semi-analytical models of the associated forces.

Climate change is modifying and will continue to modify storm occurrence statistics, as well as average wind, wave and current conditions. It therefore has an effect on the producibility of farms, as well as on the sizing of machines in terms of fatigue and extremes. Exploiting climate-related issues for offshore wind applications is a major challenge for the industry.

Sizing offshore wind turbine systems and sub-systems and in-service monitoring:

In this area, it should be noted that an increase in the maturity of floating wind turbines is critical if France is to meet its 2050 deployment targets.

These systems are already in operation in several pilot farms in France and abroad, but the transition to commercial scale requires the technologies to be de-risked and their competitiveness to be accelerated.

Offshore maintenance of these systems is a major hurdle that needs to be overcome if we are to catch up with the costs of land-based wind power. For the time being, heavy components can only be maintained by bringing the machines back to port, which leads to additional costs that need to be eliminated. We therefore need to develop technological solutions capable of replacing heavy critical components such as the blades or turbine gearbox at sea, from a floating support (the wind turbine float).

At the same time, it is critical to reduce uncertainty about weather windows by improving short-term forecasts using statistical learning methods that combine numerical model forecasts with historical data and real-time wind and wave measurements.

In-service monitoring of floating wind turbines should also provide a better estimate of their state of wear (fatigue) and enable maintenance plans to be adjusted to reduce costs. Setting up digital twins is therefore a major area of research for the industry. Research activities targeting the improvement of numerical models of aeroservo-hydro-elastic behaviour are central, as is the development of sensors capable of providing information on the key parameters to be used as inputs to these numerical codes.

Floating wind turbines also carry two critical technological building blocks for which advances in research are expected. The first is the dynamic power cable, which exports power from the wind turbine to the electrical substation. This component is known to be one of the most significant sources of potential failure, but its hydro-mechanical behaviour still needs to be qualified, particularly through tests at sea or in a representative environment, which should also be used to validate sensors and measurement protocols capable of representing its deformations and failures. Anchoring lines are a second sensitive technological building block. Developments are expected in the field of ageing qualification of synthetic ropes (e.g. polyamide) and the pooling of anchors, or even anchor lines, to help reduce installation, maintenance and decommissioning costs for floating wind turbines.

The electrical substation is another critical component of the farms. Any failure in this system, which collects the power from all the wind turbines on a farm and exports it to the mainland, would result in a total loss of the energy produced. Research needs to be carried out to prepare for the increasing power of the farms (towards 1 GW or more per farm), their distance from the coastline, which will require them to use direct current to limit load losses, and the greater depths expected for the next commercial floating wind farms, which will require the installation of floating electrical substations.

2 – Main contributions of the French communities through ANR cofounding: A brief analysis of the outcomes of the different projects is presented:

SYMBIOSE: Study and Optimisation of the Microalgae-Anaerobic Bacteria Coupling for Biological Energy Production from Primary Biomass and Organic Waste.

Combining microalgae cultivation and anaerobic digestion to produce energy Joint recovery of liquid, solid and gaseous effluents to produce bioenergy The aim of the project is to combine microalgae cultivation to capture CO2 from industrial sources with an anaerobic digestion process to recycle the nitrogen and phosphorus in these cultivations and produce methane. The project is based on recent advances in the control of both microalgae cultures and anaerobic digestion processes, considering the ecology of microbial communities and incorporating an eco-design approach. New avenues of research have therefore been explored, including the search for suitable complex photosynthetic biomass, the use of an anaerobic digestion process to co-digest organic residue with algal biomass, and the recycling of mineralised nutrients to the microalgae culture. The SYMBIOSE project uses mechanisms found in the natural environment, but places them in optimal conditions to address energy, environmental and industrial issues. The advances made will help to support the majority of projects concerned with the mass production of microalgae, effluent treatment and bioenergy production. From understanding biological processes in the natural environment to an integrated biogas energy production process Our approach is based on phenomena observed in natural aquatic environments. Selecting populations of microalgae capable of growing rapidly from the liquid residues of anaerobic digestion was a major stage in the project. By highlighting the interactions between the microalgae and the aerobic bacteria, it was possible to identify optimised microbial consortia. Optimum conditions for the anaerobic conversion of these biomasses into biogas and mineral elements were identified, enabling the expected performance to be determined in terms of energy production and nutrients to be mobilised for cultivation. The results of these two tasks have led to the design of mathematical models capable of representing and optimising the biological mechanisms involved. These models are also being used to implement monitoring/control systems and to size installations. The analysis of the coupled system and the prospects for industrial deployment are supported by an eco-design approach based on life-cycle analysis. Finally, all the concepts developed were tested on a pilot system combining phytoplankton biomass cultivation and anaerobic digestion on a laboratory, pilot and pre-industrial scale (60 m2 cultivation tank and 1 m3 digester). Major results Among the project's major results, the cultivation of microalgae on a digester effluent and the methanisation of these microalgae are unitary operations that have proved possible for a wide variety of microbial consortia. The anaerobic digestion of microalgae has made it possible to identify the limiting stages in this process and the associated optimisation strategies. Modelling this process has led to the identification of optimal conditions for energy production and nutrient remobilisation. The environmental impacts associated with the industrial deployment of the system were assessed and the unit processes with the greatest impact were identified, with a view to their eventual optimisation. The implementation of two coupled systems on a laboratory, pilot and pre-industrial scale is a significant step forward, offering new prospects for investigation into fundamental aspects and industrial outlets. A patent on the anaerobic digestion/microalgae culture coupling process has been submited.

KineHarvest: Efficient electrochemical kinetic energy recovery system using nanomaterials.

The KineHarvest project aims to develop an electrochemical kinetic energy recovery system that converts the low-frequency (0.1~10 Hz) mechanical energy of various kinetic motions such as human body movements. We have developed a new electrochemical energy recovery cell with a hybrid structure (called a hybrid cell) consisting of a supercapacitor-type electrode and a battery electrode. The kinetic conversion to electrical energy occurs through a selective ion scavenging effect on the surface of the supercapacitor when there is an electrolyte flow. Based on this new concept, we will study the optimisation of the phenomenon through the use of electrolyte and electrode nanomaterials chosen to exalt the efficiency of ion scavenging and thus increase the output voltage. To this end, we will seek to understand the fundamental principle of flow-induced ion scan behaviour using the microfluidic tomography technique we have recently developed. The following challenges are addressed:

1. Current energy harvesting techniques based on triboelectricity or piezoelectricity are optimised for high-frequency vibrations (20~500 Hz). However, naturally available kinetic energies (e.g. human movements, winds, waves, ocean tides, etc.) generally have a frequency of less than 10 Hz and irregular pulses. Energy recovery from these low-frequency movements has been little explored and is therefore the motivation for the KineHarvest project.

2. The phenomenon of ion scavenging induced by liquid flow - the key principle of our energy recovery system - is new, and its mechanism is not yet understood. Technically, increasing the amount of ionic charges swept up by kinetic motion will improve energy conversion efficiency. To date, there has been no experimental characterisation to quantitatively assess the influence of ion scavenging on electrochemical response. In particular, our new microfluidic analysis method is capable of performing 3D flow tomography and real-time monitoring of fluctuating shear at the local site near the interface. This technique is therefore ideally suited to correlating hydrodynamic parameters and electrochemical response by ion scanning at the electrolyte-electrode interface.

3. A key condition for achieving the maximum output voltage of the hybrid cell is the selectivity of the ion-scanning behaviour, which should only involve the supercapacitor electrode. Therefore, the opposite electrode must achieve ion storage in the electrode volume as in a battery material. However, even battery materials contain ions adsorbed on their surface which can be swept away under the flow. It is therefore necessary to understand the influence of these adsorbed ions on charge storage.

The targeted hybrid cell performance is the kinetic input current density of 1 mA/cm2 to the human body, which is an order of magnitude higher than that of state-of-the-art piezoelectric and triboelectric systems. The output impedance at maximum power will be a few tens of Ohm, which is also four to five orders of magnitude lower than the state of the art. Such a highly efficient kinetic energy harvesting principle will be applied to wearable self-powered devices and the Internet of things (IoT) for wearable gadgets by efficiently transforming the energy of all kinds of body movements and floating vibrations into electricity.

CREATIF Real-time control and simulation of floating wind turbines and grid integration

The aim of the "CREATIF" project is to implement a new "hardware-in-the-loop" type "real-time" simulation tool offering complete interaction models between the various components of a floating wind turbine, in order to: Develop new control and estimation architectures based on non-linear approaches, effective over a wide operational range for both energy production and wind turbine stabilisation, and relatively simple to adjust; optimise the architectures and sizing of energy conversion chains and their integration into the grid on the basis of technical and economic criteria. The project partners cover all the components and systems involved in the floating wind turbine process: wind turbine dynamics under the combined action of swell and wind; energy conversion chain and network; control strategies; hardware simulation and Power-Hardware-in-the-Loop.

FLORIDA: Interactions and wake dynamics of floating wind turbines:

With the imminent development of floating offshore wind farms, new questions are emerging about the wake of floating wind turbines (SWTs). The additional movement imposed by the floating platform affects the interaction of the turbine with the incident wind field and therefore the generation of its wake, a phenomenon that is already very complex for land-based machines. The different types of platform have a specific damping of their motion induced by the waves and by the interaction of the turbine with the incident turbulent wind field. This results in periodic movements, the signature of which can be seen in the overall wake dynamics and which can even trigger a more rapid absorption of the wake velocity deficit. In wind farm configurations, these wakes encounter other floating wind turbines and have an impact on their performance and hydrodynamic behaviour. It is therefore important to understand the wake dynamics of floating wind turbines in order to optimise the layout of the farm and reduce fatigue loads and therefore maintenance times (which are costly and time-consuming at sea). In the systematic study of the wake dynamics of wind turbines, the relevance of wind tunnel experiments is widely recognised. In the FLORIDA project, we therefore propose to extend the investigations to floating wind turbines by adding predefined movements to the wind turbine models, under realistic or user-defined turbulent flow conditions. The aim is to identify the impact on wake dynamics of buoyancy motions in different degrees of freedom, with an emphasis on wake meandering. In addition, special turbulent flow conditions are used to selectively study the influence of different length scales on this meandering. Based on the experimental data, new wake models will be developed for floating wind turbines to capture the meandering dynamics added by floating. The approach involves both adapting existing dynamic models and extending them with stochastic methods. The models will be used to generate wind fields including the disturbance generated by the presence of the wake of a floating wind turbine located upstream, which will constitute input data for coupled simulations and wave tank experiments in which (1) software calculates the aerodynamic loads acting on the floating wind turbine with disturbed incident velocity fields and (2) the aerodynamic loads are emulated with 6-degree-of-freedom actuators. The influence of wake disturbed wind fields on the hydrodynamic response of the float will then be studied. The two partners are combining their expertise in the modelling of wake dynamics, the wave response of floating platforms, hybrid experiments in wave tanks and the physical modelling of wind turbines and the generation of turbulence with user-defined characteristics.

SMARTMOORING: Smart mooring for safe and efficient ocean energy production.

The SMARTMOORING project focuses on the development and validation of moored marine energy systems that will enable data-driven design optimisations, predictive maintenance procedures and optimisation of energy efficiency during operation. Intelligent mooring systems will contribute to the creation of more reliable marine energy units with significantly higher energy conversion efficiency and lower operating costs. The technologies that will be developed and validated are relevant to a wider range of applications, including floating wind/solar, as well as applications outside the energy sector. The concept is based on fibre optic sensing, embedded in mooring components, which provides real-time information on component shape, load, vibration signature and temperature along the entire length of the component. along the entire length of the component. The project will address a number of challenges at different levels (fibre optic sensing, integration of the fibre into the mooring components, modelling and testing), enabling the technologies to be taken from TRL2 to TRL5. The value created by the project results will be demonstrated in two use cases: a mooring rod in CorPower Ocean's wave energy converters (EC), and a carbon rope in Minesto's tidal EC. These players in wave energy anticipate significant gains in terms of savings, the environment and operational efficiency, thanks to access to SMARTMOORING sensors during the design and field operation phases.

DIMPACT: Sizing floating wind turbines to take account of the impact of breaking waves.

The DIMPACT project has produced a number of major results:

The definition of an integrated methodology for taking account of breaking waves in the design of floating wind turbines, based on:

• An innovative approach for the choice of the sea state, known as the design state (the most dangerous for the machines), which explicitly integrates the contributions of the forces induced by breaking waves on floating wind turbines.
• New formulations for considering the impact forces of breakers in numerical simulation models of the coupled behaviour of floating wind turbines.

These developments were made possible with

• Basin tests to characterise the waves and forces on a model of floating wind turbines set in motion by a hexapod,
• Numerical simulations giving access to parameters 'hidden' in the basin tests, in particular the fluid speeds in the crest of the breakers,
• Trials at sea, which provided new insights into the properties of breaking waves at sea and the complexity of measuring the response of floating wind turbines to wave impact forces.

They also led to several major scientific discoveries in the field of wave breaking physics and the interaction of breaking waves with offshore wind turbines:

• The discovery of a breaker detection criterion in the simplified (so-called linear) wave models used in the numerical codes used to simulate offshore wind turbines,
• A relationship enabling the severity of breaking waves to be established from the information available on linear wave models,
• An empirical law linking the severity of waves to the impact forces on a cylinder, which makes it possible to estimate the forces on a float by knowing only the wave properties.

They are transferred to industry in two forms:

• An implementation in the OpenFAST and DIEGO numerical codes for simulating floating wind turbines,
• A reference in the DNV document RP-C205, which is central to the sizing procedures for floating wind turbines.

POWSEIDOM: Deployment of wind and turbulence observation resources in the Mediterranean.

The main results and highlights of the project are listed below :

Development of a methodology for characterising turbulence intensity (TI) using profiling lidar, known as the "variance method". This method reduces the TI measurement error by 20% compared with the standard method used in the industry. However, this method only applies in the specific case where the wind propagates along a pair of lidar beams (beam 1/beam 3 or beam 2/beam 4).

Lidar data acquisition on Planier Island. The instrument was deployed in December 2022. Its deployment has been made permanent.

• Characterisation of the wind resource and atmospheric properties using lidar measurements collected on Planier Island.
• Acquisition of a fixed vs. mobile lidar dataset collected in a controlled environment.
• Quantification of the sources of error generating a difference between the standard deviation values (turbulence) measured by a mobile lidar (floating lidar) compared with those measured by a fixed lidar. This study follows the simultaneous acquisition of data from a lidar mounted on a mobile structure and a fixed lidar installed nearby.
• Development of a preliminary motion compensation algorithm for TI measurements using floating lidar.

FISHOWF: Monitoring strategies to identify and assess the effects of offshore wind farms and their connections on fish populations.

In France, the rapid development of offshore wind power requires in-depth monitoring of fish communities to detect and quantify the potential effects of wind farms on ichthyofauna. The traditional experimental fishing methods used in regulatory impact studies on fish are not sufficient to meet this objective and to respond to societal concerns. It is therefore necessary to develop effective and appropriate methodological strategies. State-of-the-art indirect approaches, such as passive acoustic telemetry, with a robust sampling plan, offer alternatives to traditional monitoring for offshore wind projects. In this context, the aim of the FISHOWF project is to develop a long-term monitoring approach to detect the effects of installed and floating offshore wind farms and their connections on fish populations. The FISHOWF project has produced several major results:

The provision of multi-scale solutions for the continuous observation of fish communities to provide a better response to the challenges facing the fishing industry.

Installation of continuous observation infrastructures in several offshore wind farms, with the deployment of acoustic telemetry receiver networks, comprising more than 48 receivers, in four wind farms at different stages of development.

Monitoring the movements of more than 300 individuals of 12 species of fish and crustaceans and their frequentation of offshore wind farms

Improving ecological knowledge of major societal issues and little-studied species

Significant contribution to the understanding of large-scale movements of species, which can be used for marine spatial planning.

A unifying monitoring strategy for the entire industry

Development of specific sampling plans and acoustic telemetry protocols to answer various questions

Recommendations on the implementation of acoustic telemetry monitoring within a park at different spatial scales

Demonstration of the relevance of a combined approach to assess the reef effect of wind farms on fish populations.

The FISHOWF project has generated various resources of interest:

• Database of individual detections in four offshore wind farms
• Compilation of regulatory halieutic monitoring of offshore wind farms
• Scripts and algorithms for managing, processing and displaying acoustic telemetry data
• Recommendations for implementing acoustic telemetry monitoring at different spatial scales
• Summary of existing methods for monitoring fish populations and recommendations for implementing complementary methods

NESTORE Nested modelling approach to MRE development and cumulative impact assessment, considering local to regional environmental and socio-economic issues.

The multiplication of activities and projects at sea increases the cumulative impacts on the marine environment. The rapid and large-scale development of offshore wind farms highlights the lack of operational tools for carrying out an integrative assessment of the cumulative impact of offshore co-activities on the Good Ecological Status of the marine environment. Against this backdrop, NESTORE is proposing a nested modelling approach for assessing the cumulative impacts, from local to regional scales, of offshore wind farm development. Wind farms, whether fixed or floating, can affect the structure and functioning of ecosystems at different scales, whether within a single wind farm or looking at cumulative impacts on the scale of a maritime coastline with the multiplication of the number of wind farms and the co-activities already present. The main objective of the NESTORE project (2022-2025) is to assess the cumulative impacts of wind farm development on marine ecosystems and to produce a set of tools for the MRE sector in order to meet the legal obligation to carry out an assessment of cumulative impacts in environmental impact studies.

The NESTORE project, which is currently underway, will produce a number of major results:

• A robust scientific methodology for assessing the cumulative impacts at different scales of offshore wind farm development and existing co-activities
• A regulatory framework for the methodology, so that the results of the cumulative impact assessment can be linked to the environmental and socio-economic objectives defined for each French coastline in the Strategic Coastal Zone Documents.
• The development of an approach for assessing the main sources of uncertainty in the results of cumulative impact assessments, taking into account uncertainties linked to tools, data and scenarios
• Application of the tools developed to various case studies covering all of France's maritime façades:
  
  In the English Channel and the North Sea, the tools will assess the cumulative impact on the scale of the coastline in order to understand the synergistic, antagonistic and additive responses of co-activities at sea with the multiplication of offshore wind farms. In southern Brittany (NAMO coast), a local-scale model will assess the cumulative impact of wind farms on the functioning of benthic ecosystems in particular. In the Mediterranean, the Gulf of Lion model is being used to assess the cumulative impact of wind farms on marine megafauna, particularly birds and marine mammals.

The NESTORE project will generate various resources of interest:

• A set of nested models with associated uncertainties at different scales to better inform decision-makers (including the advancement of knowledge on the assessment of cumulative impacts)
• An analytical and operational study of the Strategic Coastal Zone Documents, with nested mapping of issues translated into management scenarios tested in trophic models.
• A public report containing recommendations and associated protocols for conducting a cumulative impact study using the NESTORE project tools.

3- Research perspectives :

For characterisation of wind energy production and weather conditions, specific research questions have been addressed in the background part of this report as for sizing offshore wind turbine systems and sub-systems and in-service monitoring which are addressing new research question presented in the beginning of this document mainly for floating structures.

Environmental and socio-economic integration of wind farms

• This is a major issue for the deployment of wind farms in France. First of all, we need to improve our understanding of the pressures induced by wind farms on ecosystems, from the benthos (life on the seabed), fish, large marine mammals and flying fauna (birds and chiropterans). The effects on the trophic chain (or food chain) also need to be examined in greater detail: the pressures associated with offshore wind farms may affect one species in particular, but may also affect others indirectly through the trophic links that connect them.
• Interactions between offshore wind farms and avifauna are one of the key issues for the industry. The knowledge gaps concern the periods and routes followed by migratory and sedentary species, as well as their behaviour as they pass through the farms. How to adapt farms to limit their interactions with birds and chiropterans is another related field of research to be explored further in the coming years.
• This illustrates a need for measurements at sea, on farms, with efforts to develop dedicated sensors for the avifauna - chiroptera compartment but which can be extended to all species, populating the coastal marine environment. These measurements must cover significant periods of time to capture seasonal and interannual variability, and ideally even the effect of climate change.
• Offshore structures are artificial reefs that increase biomass through bioufouling (seaweed, mussels, etc.) which then attract a range of species potentially exploitable by fisheries. The way in which wind farms modify the coastal environment and the way in which these changes can be exploited by fishermen are the subject of research work that must continue in order to improve the interactions between this sector of activity, which is a decisive player in the deployment of offshore wind farms.
• The effects of wind farms on ecosystems also need to be seen in the context of the multiple pressures from human activities in addition to those from wind power. Numerical models capable of representing these cumulative effects are needed to objectivise the impact of offshore wind farms on the environment and to better qualify them in order to provide the best measures for optimal environmental integration of this technology.
• Environmental integration is one of the issues most often raised during the public debates that precede the deployment of wind farms. Improving environmental (and socio-economic) integration should help to improve the public's perception of this sector. Sociological studies will certainly be needed to gain a better understanding of the sphere of stakeholders involved in the public debates, to better understand their needs and to integrate them into the definition of the farm projects in order to increase their endorsement by the stakeholders.

Means of observation

Oceanic instrumentation is essential for exploring and monitoring marine environments. However, several obstacles complicate information collection in these extreme environments: temperature, pressure, corrosion, and salinity. 143 ANR projects have enabled the development of measurement tools deployed in space, on the surface, and at the depths of the oceans, particularly the new Argo floats. These technological advances have given rise to new acoustic, chemical, and electromagnetic sensors that improve our understanding of the ocean, facilitate weather forecasts, pollution detection, tsunami anticipation, and support climate policies.

Scientific background

This thematic portfolio covers the development of innovative sensors, robotised and remotely operated equipment for observing the oceans from space and underwater, and sampling methods. Scientific instrumentation plays a key role in exploring and understanding ocean environments. In these “hostile” environments, instruments need to be waterproof, withstand high pressure, immersed in particularly corrosive salty conditions, as well as tolerate living environments that can generate major bio-fouling challenges. The instruments need to be energy efficient as they are not connected, and small to make them easier to use. For all these reasons, ocean instrumentation involves a first stage of marinated equipment developed for studies in laboratories, test basins and more accessible environments.

Impacts on public policies and socio-economical innovation

Instrumentation underpins all research operations and their applications in monitoring ocean health and biodiversity. New instruments, sensors and devices are developed with support from private companies, which later market the products. It is challenging for the industry to participate in the European and world market. For example, NKE, a small company based in Brittany produces 20% of the world’s Argo floats, developed in collaboration with Ifremer and France 2030.

Main outcomes of the ANR-funded projects

New sensors have been developed using innovative technologies for marine applications of in situ chemical, acoustic and electromagnetic sensors for environmental and risk monitoring. These include the detection of heavy metals such as mercury, cadmium and lead in marine ecosystems. To monitor the marine environment, the bio-detection of microalgae has enabled us to detect pollution based on phototactic behaviour influenced by pollutants. A new generation of Argo floats will enable us to explore to depths of 4,000 metres initially and 6,000 metres in the second phase, increasing the number of physical and biological parameters measured. For tsunamis, an early warning system has been developed using modelling and detection based on ionospheric and mesospheric signatures. HF radar and over-the-horizon radar allow us to analyse all ship movements. A particular application of satellite detection and SAR facilitates the detection of oil pollution. Sailing robots, combined with modular sensor systems, enable autonomous or semi-autonomous mobile platforms to collect marine data, providing flexible and persistent monitoring of physical, chemical and biological parameters. The use of satellite ocean observation tools for mapping and modelling – coupled with in situ observation of oceanographic and atmospheric phenomena – has been developed in numerous projects. Electrolytic marine antifouling coatings have enabled the creation of electro-active polymer coatings that prevent the adhesion of marine biofilms without being toxic for the marine environment. Innovative sensors for monitoring faecal pollution use a portable, micro-fluidic device to detect pathogenic Escherichia coli bacteria in real time using immunochemical and electrochemical techniques. Coupled with AUVs, it is now possible to monitor and control the coastal environment in real time. Advanced machine learning has been used for image analysis of plankton benefits in situ from the development of automated methods. AI has also improved the efficiency of glider missions by increasing the detection accuracy of remotely operated vehicles (ROVs), making it possible to detect and classify underwater objects and species.

Conclusion and research perspectives

It is important to continue focusing on cross-disciplinary and cross-scale integrations, particularly regarding biogeochemical fluxes and sediment dynamics. The next step is to contribute more actively to environmental forecasting with real-time data for risk management and climate resilience strategies, highlighting the societal relevance of hydrodynamics research.

Tara expedition

The Tara Ocean Foundation conducted a major transoceanic and transdisciplinary scientific expedition, supported by the ANR through 12 projects, the Tara Oceans expedition. This expedition collected about 40,000 plankton samples across the oceans, creating the largest public database on plankton biodiversity (250 billion DNA sequences, 7 million images). It enabled a better understanding of marine ecosystems through the discovery of new species, genes, and viruses, revealing the unknown importance of plankton, viruses, and prokaryotes in the carbon cycle and climate regulation. They have also contributed to environmental governance, public awareness, and technological and biotechnological innovations (sensors, AI, potential therapeutic agents). Ongoing (Tara Pacific, Mediterranean, Microplastics) and future campaigns - on the study of corals and circumpolar ecosystems - will extend these advances in an increasingly international and interdisciplinary framework.

Eric Karsenty: EMBL, Romain Troublé: Fondation Tara, Gaby Gorsky: CNRS/Imev

1) Scientific Background:

The ocean ecosystem covers ~70% of Earth’s surface and contains 97% of all water on our planet. Plankton are the dominant life forms in the ocean and comprise highly dynamic and interacting populations of viruses, bacteria, archaea, single-celled eukaryotes (protists) and animals that drift with the currents. Together, these mostly microscopic organisms play a major role in maintaining the Earth system by, for example, carrying out almost half of the net primary production on our planet and by exporting photosynthetically fixed carbon to the deep oceans. Plankton also form the base of food webs that sustain the complexity of life in the oceans and beyond. Finally, those organisms contain old life forms and can help us better understand the origins of the genetic complexity that led to the emergence of complex eukaryotic organisms like us. With the goal to gain a holistic understanding of this complexity, ocean ecosystems biology investigates how biotic and abiotic processes determine emergent properties of the ocean ecosystem as a whole. Analogously to systems biology studies that require well-characterized cell lines or model organisms for a mechanistic, molecular understanding of their phenotypes, achieving this goal will require to establish an inventory of the ocean’s plankton, to collect data on the interactions of organisms with each other and the environment, and to integrate this information in the context of physicochemical boundaries in the ocean ecosystem across space and time. Global-scale efforts, although challenging, are poised to offer new insights into each of these directions and should make possible better predictions of the impact of climate change on this crucial component of the biosphere.

Planetary-scale studies of open-ocean organisms have long been the subject of dreams — from the Challenger Expedition (1872–1876), which led to the discovery and description of countless eukaryotic organisms, to the Global Ocean Sampling Expedition (2004–2008), which pioneered the genomic exploration of ocean microbial communities. The Tara Oceans expedition was conceived in 2008 as a multi-disciplinary project and team, including researchers with expertise in biological and physical oceanography, marine ecology, cell and systems biology, genomics, imaging as well as (bio)informatics, with a common
goal to study epipelagic and mesopelagic plankton on a global scale from gene to community level. At its beginning, this project, which would use the 36-m schooner Tara for the expedition and the whole support and expertise of the Tara Foundation, required trade-offs and innovations in sampling needs and capabilities. Enormous planning was required to identify oceanic areas of scientific interest; to negotiate foreign national waters sampling permits, ports and logistics; and to resolve intense debates across disciplines to establish baseline sampling protocols.

Finally, in September 2009, Tara set sail from Lorient, France, partially navigating through stormy weather and around pirates, to collect samples for analysis by state of the art molecular and imaging technologies. Interestingly, high throughput deep sequencing technology just started to be available at a relatively affordable price almost simultaneously with the start of the expedition. Similarly, high throughput imaging technology applied to protists and zooplankton was just becoming available. Artificial intelligence with machine learning were starting to be available and members of the consortium applied it to analyze immense data sets that came out from the expedition.

The primary objectives of Tara Oceans have been to generate a baseline understanding of plankton diversity, interactions, functions and phenotypic complexity across global taxonomic and spatial scales, and to communicate the scientific findings to the public and policymakers. In addition, all protocols, data and analyses are open access to promote further research. Working towards these goals, the consortium grew organically, and by the time the expedition was completed in 2013, Tara Oceans comprised 19 international partner institutions committed to generating, organizing and analyzing the vast volumes of new and heterogeneous data derived from the thousands of plankton samples collected worldwide.
Complementary expeditions exploring the deep ocean as well as local-scale and other global- scale plankton surveys have also been undertaken, some of which based on the principles developed in the Tara Oceans project.

The French ANR has heavily supported the Tara Oceans project and here we summarize the results of 12 such projects. One of them, Oceanomics, covers the whole program of Tara Oceans and is really the foundation of the global analysis. The other 11 projects cover more specific aspects or applied projects using the data of Tara Oceans.

Below are summaries of the projects:

Oceanomics, Poseidon, Prometheus, Tara-Girus: These projects have developed an integrative approach to exploring plankton marine ecosystems end to end from viruses to small metazoans including bacteria and protists. They focused on the description of the species and gene biodiversity, reconstructing many marine metagenomes from shot gun sequencing and generating metatranscriptomes. This has enabled the identification of many new viral, bacterial and eukaryotic species and genes/genomes. Some of biotechnological interest. This also led to several studies on the origin of viruses and eukaryotes. It was important to use both genomic and imaging techniques to better understand the impact of the environment and global ocean circulation on ecosystem structure and dynamics as well as the impact of climate change on the biogeography of planktonic organisms.

Phytback: Phytback studied phytoplankton diversity and responses to environmental variations and their role in the carbon cycle.

Mappi: This project is technological. Its function in the global Tara Oceans project has been to develop new analytical and organizational methods of large sequencing data sets.

Amphictot: Amphictot is an applied project aiming at developing new engineered amphidinolids based on rare marine macrolids with the aim of developing new anti-cancer chemotherapies.

Phytoiron: This project investigated the role of iron in phytoplankton productivity. In particular it characterized entirely new Iron transport systems mediated by a ubiquitous protein from phytoplankton.

Samosa: This project combined laboratory studies of gene expression patterns associated with controlled environmental conditions with the study of in situ genomes and transcriptomes of synechococcus extracted from metagenomes and metatranscriptomes generated during the Tara Oceans expedition.

Hydrogen: Analyzing very large datasets generated by metagenomics and metatranscriptomics like in the Tara Oceans or in the gut microbiome project is challenging in terms of machine time. Hydrogen has developed new algorithms implemented in a software named SIMKA that largely solves this issue.

Cinnamon: Global warming leads to an increase in ocean temperature and in iron poor zones which in turn affects phytoplankton growth in about 35% of the Ocean. This project studies the adaptation of synechococcus and picocyanobacteria to changes in iron concentrations both in laboratory studies and globally in situ using Tara Oceans data.

Coralgene: Coral reefs harbor about 30% of marine biodiversity and provide food to 1 billion people. Coral reefs are strongly exposed to global warming and composed of a poorly known and understood ecosystem composed of the Holobiont, symbiotic algae’s and many unknown other microorganisms. This project has involved a holistic sampling of 35 coral reef systems in the Pacific Ocean during the Tara-Pacific expedition and brought back a wealth of molecular and morphological data opening the way to a first global description of coral reefs exposed to various environmental conditions.

These projects offer perspectives for a better understanding of the planetary life reactor that oceanic plankton is, highlighting the importance of an integrated approach to managing essential marine ecosystems. After the results were firstly published in Science magazine in 2015, Tara Foundation bridged with Institutions and the United Nations in order to contribute to new and innovative ocean governance tools, to promote the use of plankton data and knowledge for predictions and monitoring. Since 2021, with the support of the FFEM and OFB, the Tara Foundation and CNRS are working on a new model, KOPAs (Key Ocean Planktonic Areas), aiming to quantify and monitor essential ecosystem functions delivered by the plankton ecosystem. This project is now leading to a concrete proposal to define planktonic hotspots on the Chilean coast, supported by the government of Chile.

2) Main contributions of the French Communities through ANR

2-1) Scientific progress; Cutting edge Science

1. Oceanomics, Poseidon, Prometheus and Tara-Girus.

Ten years ago, plankton knowledge was limited by technological and logistical constraints on holistic ocean life exploration. From the ~40,000 plankton samples collected across all ocean provinces and the spectrum of life—from viruses to animals in their physical and chemical context, these projects built the largest public database on the diversity of a planetary biome. This database includes ~250 billion DNA sequences and ~7 million plankton images from ~8,500 planktonic communities, covering 10 orders of magnitude in size. Samples were collected at 210 contrasting ocean sites at three depths, including the mesopelagic zone.
In addition to advanced genomic techniques and high-throughput microscopy, novel in situ (UVP) and benchtop (ZooScan) imaging methods have been used to study macroscopic protists, metazoans and aggregates and their role in biogeochemical cycles.
The data was compiled, sorted, analyzed, and made widely available, primarily through adapted spaces on existing European web platforms (ENA/EBI/EMBL, PANGAEA, SEANOE), as well as newly created online tools for data exploration and sharing (e.g., EcoTaxa, OBA).
Through analyses published in 153 scientific articles, these projects produced a global and uniform vision of:

1. Plankton biodiversity on a planetary scale from viruses to small metazoa.
2. The organization of biodiversity in relation to local biotic and abiotic environmental parameters and water mass dynamics (seascape).
3. The relationships between biodiversity structure/dynamics and key ecosystem functions, such as the carbon pump.
4. The probable evolution of plankton biodiversity and biogeography until the end of the century.

These pioneering systemic results were notably published in a 2015 Science special issue with six articles, followed by over 15 publications in Nature, Cell, and PNAS, with several featured-on journal covers.

Discoveries

The project revealed an unexpected diversity of species, genes, and novel functions in the ocean. It reconstructed the planetary plankton interactome, exploring multi-scale biotic and abiotic relationships that structure marine microbiome biodiversity, generate major ecosystem functions, and transform under Anthropocene environmental gradients.

Public ‘Tara Oceans/OCEANOMICS’ databases have become standards for plankton analysis, with over 2000 publications produced by the international community, including in top-tier journals.

Some key features of the discoveries include the unveiling of 47 million genes out of 35 000 taxa of prokaryotes, 200 000 types of DNA viruses with unknown hosts (only 39 were known before), 130 000 protists genera (10 times what was identified manually) harboring 116 millions genes coding for mostly unknown proteins.

The new sampling approach of Tara Oceans has also allowed to study giant viruses (Giruses) in an unprecedented way. An unexpected high amount of such viruses has been discovered and new interactions between giruses and eukaryotic species have been revealed. A phylogeny-guided genome-resolved metagenomic survey led to the discovery of plankton-infecting relatives of herpesviruses that form a putative new phylum dubbed Mirusviricota. The virion morphogenesis module of this large monophyletic clade is typical of viruses from the realm Duplodnaviria, with multiple components strongly indicating a common ancestry with animal-infecting Herpesvirales. A substantial fraction of mirusvirus genes, are closely related homologues of giant eukaryotic DNA viruses from another viral realm, Varidnaviria. Mirusviruses are among the most abundant and active eukaryotic viruses characterized in the sunlit oceans, encoding a diverse array of functions used during the infection of microbial eukaryotes from pole to pole. The prevalence, functional activity, diversification and atypical chimaeric attributes of mirusviruses point to a lasting role of Mirusviricota in the ecology of marine ecosystems and in the evolution of eukaryotic DNA viruses.

Another key outcome of the projects has been the discovery of many symbiotic systems involving interactions between protists as well as protists and prokaryotes as well as whole functional genome units of pro and eukaryotes inside viral genomes.

Using non-intrusive in situ UVP imaging technology, new data was collected on macroscopic organisms and marine snow. The global analysis of plankton images including fragile plankton and aggregates usually destroyed or damaged by conventional sampling has highlighted that in oligotrophic waters 1) the ecological roles of rhizarians, hitherto neglected, have been underestimated. Their biomass is equal to that of all other mesozooplankton and their contribution to carbon fluxes greater than that previously estimated. 2) New data from gelatinous plankton show that it can modify trophic structures and the carbon cycle. 3) Linking genes to ecosystems shows that prokaryotes and viruses contribute significantly to carbon export and that parasitism, infection and predation are important processes correlating with carbon export intensity. 4) In productive systems along the equatorial Atlantic and Pacific, evidence of increased marine snowfall contributes to carbon storage in the deep ocean.

More generally the organization of the data allows to examine organisms’ interactions across a size spectrum ranging from a few microns to millimeters.

Importantly, the unique structure of Tara Oceans data that combines genomics, species and environmental data, has allowed to build predictive models of the evolution of the biogeography of plankton biodiversity at the end of the century using the IPCC models of temperature changes.

2. Coralgene

Coral reefs have often been at the forefront of climate change research due to coral bleaching, ocean acidification, and concerns related to reef growth crises. Recent genomic advances have revealed that the complexity of coral genomes is similar to that of vertebrates. Adding to this complexity is the obligatory photosymbiosis of corals with microalgae. Beyond this symbiosis, corals also host a largely unknown array of bacteria and viruses, forming a complex symbiocosm known as the holobiont, aligning with the current revolution in studying microbiomes in the animal world.

The Tara-Pacific expedition has been an east-west transect from Panama to Japan and a south-north transect from New Zealand to Japan, sampling three species of corals, one fish species, and surrounding water under the concept of a mini-ecosystem in 32 island systems. The expedition and the analysis build on the systemic approach of Tara Oceans in the sense that corals and their associated ecosystems are examined as a whole including environmental data.

During its 2-year voyage, the Tara Pacific expedition sampled coral ecosystems from 32 islands across the Pacific Ocean and ocean surface waters at 249 locations, resulting in the collection of nearly 58 000 samples. At each reef site, two species of scleractinian corals, one
hydrocoral, and two species of fish were sampled and contextualized with water and aerosol samples as well as with environmental data obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. This led to approximately 102 Terabytes of metabarcode with different primers, metagenomes, and metatranscriptomes, as well as more than 5 000 metabolomic profiles. Metabolomes were described by using both liquid chromatography–high-resolution mass spectrometry (for the lipidome) and nuclear magnetic resonance imaging (for the hydrophilic component) analyses to assess and annotate a broad range of the metabolome of three coral holobionts. This unique multidimensional framework also includes a large number of concomitant metadata collected side-by-side, all now publicly available.

Discoveries

Two coral genomes, Porites lobata and Pocillopora meandrina were assembled and their genomes annotated revealing higher gene number than that found in other public coral genome sequences: 43,000 and 32,000 genes, respectively, which may be explained by a high number of tandemly duplicated genes. Microbial communities have been found to vary among and within the three animal biomes (coral, fish, and plankton) geographically. Within the coral microbiota, Endozoicomonadaceae, a globally distributed bacterial family, has been identified as a key bacterial symbiont of corals. A specific analysis of this taxon has now shown that the same clades are found across the Pacific Ocean but are host-specific at the species level and may harbor different specific functions. A survey of the viral compartment of the coral holobiont, found heritable integrations of multiple Dinornavirus (a dinoflagellate-infecting non-retroviral RNA virus) endogenous viral element genes in Symbiodiniaceae scaffolds (especially that of the genus Symbiodinium) from within the cnidarian metagenomes. Such a result suggests widespread and recurrent or ancestral integration and conservation of these endogenous viral elements, which might have a role in reef health, for example, as an antiviral mechanism.

The 32 archipelagos surveyed made for formidable natural laboratories and offered a wide range of environmental conditions in terms of temperature, acidification, and reef health state, making it possible to study the relationships between environmental and genetic parameters at large spatial scales. As an example, we provide evidence of high host–photosymbiont fidelity across environments in Pocillopora corals, with coral and microalgal gene expression profiles responding to different drivers.

Overall, the results indicate a three-tiered strategy of heat resistance in Pocillopora underpinned by host–photosymbiont specificity, host transcriptomic plasticity, and differential photosymbiotic association under extreme warming.

3) Phytback, Phytoiron and Cinnamon

Beyond the genomic, morphological and functional characterization of planetary ocean ecosystems, there was from the outset a clear vision in the Tara Oceans consortium that the data could be used to address environmental issues related to global warming. We already saw this in the resumé concerning the first 3 projects. These 3 projects are somehow related to environmental issues. The Phytback project aims to investigate the adaptation of phytoplankton cell size and shape in global circulation models. Phytoplankton communities are size-structured, and ecological functioning depends strongly on cell size and shape. Furthermore, phytoplankton size will influence the effectiveness of the biological carbon pump, through which carbon is sequestered from the atmosphere into the ocean interior by cell sinking. The project involves building models that can be used to formulate quantitative, predictions, to be tested in experimental setups and by using ecological and genomic data from the Tara Oceans expedition. Phytoiron characterized entirely new Iron transport systems mediated by a ubiquitous protein from phytoplankton. The CINNAMON project validated the existence of distinct thermotypes within the CRD1 clade, i.e., strains exhibiting different thermal tolerance ranges. It also highlighted specific characteristics: (i) physiological traits, including their low growth rates, low photosynthetic activity, and high repair rates of damage to photosystem II, and (ii) genomic features of the CRD1 and EnvB ecotypes compared to Synechococcus ecotypes inhabiting other ecological niches. These traits could be involved in adaptation to iron deficiency and/or temperature variations.

The issues addressed in those 3 projects need to be properly understood in order to progress in the study of the reaction of planktonic ecosystems to climate change, in particular in relation to iron availability and function.

4) SAMOSA

Oceans are particularly affected by climate change, which notably causes concomitant rises of i) average seawater temperature, ii) flux of UV radiations reaching the sea surface and iii) proportion of the ocean covered by nutrient-poor oceanic waters. One major challenge for understanding the impact of these processes on the whole ocean is to study the capacity of photosynthetic organisms (phytoplankton) to acclimate (physiology) and adapt (alteration/acquisition of genes) to these changes. Marine cyanobacteria belonging to the Synechococcus genus are among the most relevant biological models to study those questions because they are ubiquitous, very abundant and easy-to-grow. They are therefore suitable for cross-scale studies, from the gene to the global ocean.

In this project, 12 strains representative of the main genetic groups of Synechococcus (3 strains for each) have been analyzed. This revealed notable differences between these ecotypes, in particular with regard to temperature ranges at which the strains can grow, which agrees well with the latitude at which they were isolated. Analysis of the response to abrupt variations of environmental parameters (high light, UV, high/low temperature) has also revealed contrasted physiological responses both between ecotypes and between stress types.
The comparison of 97 picocyanobacterial genomes, including 32 new ones, assembled and annotated in the framework of SAMOSA, led to the identification of core gene repertoires and sets of genes specific of one group or shared by several groups of strains. The latter genes are good candidates to play a role in the adaptation to specific environmental conditions.
Finally, the diversity and distribution of Synechococcus at the global ocean scale has been determined through the analysis of 111 metagenomes from the Tara Oceans expedition, using a marker gene providing a good discrimination between the various genetic groups within this genus. This allowed to unveil the presence of groups whose abundance was so far widely underestimated, to identify novel groups for which there are no cultured representatives, and to delineate environmental conditions in which these different populations preferentially live.
Together with the results of Phytback, Phytoiron and Cinnamon, this provides invaluable data to be used in future models of biodiversity evolution with climate change at the planetary level.

5) MAPPI and HYDROGEN

Analyzing very large datasets generated by metagenomics and metatranscriptomics like in Tara Oceans and Tara Pacific is challenging in terms of sequencing processing and data assembly. Mappi and Hydrogen are working on algorithms allowing to improve the speed of data treatment. In particular, Hydrogen has developed new algorithms implemented in a software named SIMKA that solves some of the issues.

6) AMPHICTOT

Amphictot is an applied project aiming at developing new engineered amphidinolids based on rare marine macrolids with the aim of developing new anti-cancer chemotherapies. Interesting chemistry results are beginning to emerge of this study that will need to be used to test the new products.

2-2) Innovation for private enterprises, for science policy, for the citizen with a focus of coastal communities

Innovation- Building on fundamental insights into planktonic ecosystems, Oceanomics developed an applied research axis to screen preserved plankton strains in the Roscoff Culture Collection (RCC) for secondary metabolites and lipids. Applications in medicine, pharmaceuticals, and dermo-cosmetics were explored. Metabolic and lipid screening, along with bioactivity testing (anticancer and antimicrobial), were conducted on a broad phylogenetic range of plankton strains. A pipeline for valorizing plankton-derived compounds is now operational. Among the 60 extracts studied, about 10 show promise as active sources for various tumor pathologies.

Generally speaking, most of the work carried out using the samples of Tara expeditions offers a treasure trove of open access data that can be used by private enterprises to look for interesting new genes and proteins. The newly developed Alphafold software that allows to predict the 3D structure of proteins from the primary gene sequence will be very useful to investigate the large number of genes with unknown function discovered in the Tara Oceans project and others that derived from it.

The massive use during the Tara Oceans expedition of UVP and ZooScan imaging instruments built at the Observatoire Océanologique of Villefranche sur mer with the potential to quickly retrieve high-quality contextualized data have positioned them as standard oceanographic instruments by the international scientific community. They are manufactured by the French company Hydroptic and distributed worldwide.

Science policy- OCEANOMICS addressed legal questions related to genetic resource access under the Convention on Biological Diversity and the Nagoya Protocol. A report was produced that served as a reference for several marine biodiversity projects in France and Europe.

Citizen awareness- All the projects associated with the Tara Oceans project had a huge impact towards the awareness of the public at large, and politicians more specifically, concerning the importance of Ocean health and the role of plankton ecosystems in the continued sustainability of the planet environment for mankind. This is regularly done through education programs for schools, all sorts of media for the public as well as through direct communication with politicians. This has been possible thanks to the close collaboration between public institutions (CNRS, CEA, ANR and the non-profit Tara Ocean foundation). In addition, several citizen science projects like Plankton Planet involving sailors around the world have been initiated in the wake of the Tara Oceans expedition.

Methodolical breakthrough- The initial Tara Oceans expedition and the associated ANR projects have initiated an entirely new approach to the study of planetary ecosystems by developing an integrated and interdisciplinary approach. The whole project was planned from the outset by an interdisciplinary group of scientists, specialists of the various planktonic organisms from viruses to zooplankton. This group devised a quantitative sampling protocol allowing to characterize those communities, and the interactions within, in quantitative terms from genomes to morphological traits. This approach is now widely used by the oceanic community. In addition, state of the art technologies ranging from high throughput sequencing to sophisticated 3D quantitative imaging associated with remote sensing and oceanographic data have been implemented in an integrative way in the project. New tools have also been developed to quantify marine organisms in situ. Ecotaxa is an entirely new software system making use of AI to classify large numbers of organisms and help using the data in complex analyses. Finally, data are stored in international data bases (ENA/EBI and Pangaea) and freely available to the community.

3) Research Perspectives

3-1 Scientific aspects

There are 2 types of scientific perspectives that may come out from the initial Tara Oceans project. One deals with the exploitation of stored data and the other from the sampling and data analysis principles used initially in new expeditions.

Concerning the scientific perspectives one can envision broadly speaking 3 directions: one deals with the complexification and evolution of life in the oceanic microbiome ecosystem, the second concerns ecology and the third molecular biology.

The data stored from the Tara Oceans expedition contain a huge amount of genome data that can be used to study the complexification and phylogeny of plankton organisms. There are already a few examples that have been published concerning the discovery of missing links in the evolution of viruses and eukaryotes as well as in viral history. A huge amount of work remains to be done in this field, and the development of AI tools may greatly help in making progress in this field. In ecology a lot remains to be done on the analysis of organism interactions, the role of symbiosis and viruses in genome evolution and complexification but also in carbon sequestration. Also using Tara Oceans data have just started to be used to study the impact of global warming on ecosystems structure and biogeography. A lot more can be done. Finally, the enormous number of unknown genes uncovered open large possibilities to study the nature and activities of the proteins encoded by these genes. Again, AI availability such as the Alphafold software should be of invaluable help to use these data.

Concerning the expeditions: The program's innovative holistic approach, both experimental and analytical, has been adapted to other large-scale expeditions of the Tara schooner:

• Tara Pacific (2016–2018): Coral ecosystems.
• Tara Mediterranean (2014) and Microplastics (2019): The plastisphere.
• Mission Microbiomes (2020–2022): Planktonic ecosystems across South Atlantic coastal gradients.
• Plankton Planet: Global, long-term cooperative oceanography

The Tara Pacific expedition has been co-funded by ANR (Coralgene) and its analysis is just starting to produce very interesting publications. The other two have also started to produce results and will undoubtedly complement very well the Tara Oceans data. The microplastics expedition has revealed interesting aspects of interactions between microorganisms and these pollutants, as well as the plastic pollution patterns of the river flows from land to see. Plankton Planet is a participative science initiative aiming at gaining large geographical data on relatively simple biodiversity measurements of plankton by individuals sailing on their own ship.

One more expedition finished in 2024 : Tara Europa/TREC expedition which is largely based on Tara Océans original sampling protocol although adapted to coastal sampling. The goal of this expedition is very complementary to Tara Oceans that was mostly pelagic. This will bring interesting data on the interaction between land and marine ecosystems as well as on the impact of Human chemical pollution through land and rivers on coastal waters and plankton ecosystems.

Two large expeditions are also planned in 2026 and 2028. In 2026-27 a second effort on coral reefs, the Tara Coral expedition, will sample the so called Coral Triangle reefs where some resilience patterns has been shown recently. In 2028-29, a round-the-south pole expedition will sample the circum-polar jet together with a few other Tara-like platforms in the context of the international Antarctica In Sync research programme.

3-2 Technical Innovation

The development of new algorithms for complex genome data analysis is promising for application. There are other aspects of those projects that can bring technological innovations like the study of global and local metabolomics. The plankton biogeography data and their evolution can be of great use for fisheries. Finally, the unknown genes can lead to the discovery of new health related products. The implementation of new plankton classifiers is being considered using recent developments in AI.

3-3 Structuration of communities

Interdisciplinary international projects organized around large scale expeditions are by essence strong structuration processes. In the case of Tara Oceans scientists working in very different fields had to learn to work together and understand various disciplines. It has been interesting to see how bioinformaticians and oceanographers had to learn their respective languages for example. Beyond this, the Tara Oceans and derived projects forced strong interactions between various European and international institutions (EMBL, CNRS, CEA, ANR, American universities, ETH in Swizerland, Japan, Italian and Spanish universities) as well as Marine biological laboratories in France (Roscoff, Villefranche sur mer, Banyuls). In 2018, the GOSEE Federation (Global Ocean Systems Ecology & Evolution) was launched, directed by OCEANOMICS coordinators (C. de Vargas, Chris Bowler, Patrick Wincker). GOSEE integrates 18 institutions, including CNRS, CEA, PSL, SU, EMBL, and the Tara Ocean Foundation.

4) Bibliography: 153 publications many in high-ranking journals (Nature, Science PLOS, Cell). It is estimated that more than 2000 papers published by non-members of the consortium used the Tara Oceans data

Publications of specific interest

1. Structure and function of the global ocean microbiome, Sunagawa, S. et al. 2015, Science 348, 6237
2. Eukaryotic plankton diversity in the sunlit ocean, De vargas, C. et al. 2015, Science 348, 6237
3. Determinants of community structure in the global plankton interactome, Lima-Mendez, G. et al. 2015, Science, 348, 6237
4. Patterns and ecological drivers of ocean viral communities, Brum, J. R., 2015, Science, 348, 6237
5. Plankton networks driving carbon export in the oligotrophic ocean, 2016, Guidi L. et al., Nature, 532, 465
6. Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses, Roux, S. et al., 2016, Nature, 537, 689
7. Marine DNA viral Macro-and microdiversity from pole to pole, Gregory, A.C., 2019, Cell, 177, 5, 1109
8. Insights into global diatom distribution and diversity in the world’s ocean, Malviya, S. et al. 2016, PNAS, 113, 11, 1516
9. Influence of diatom diversity on the ocean biological carbon pump, Treguer, P. 2018, Nature Geoscience, 11, 27
10. Gene expression changes and community turnover differentially shape the global ocean metatranscriptome, Salazar, G. et al. 2019, Cell, 14, 179, 5, 1068
11. Tara Oceans: towards global ocean ecosystems biology, Sunagawa, S., 2020, Nat. Rev. Microbiol., 18, 8, 428
12. Biogeography of marine giant viruses reveals their interplay with eukaryotes and ecological functions, Endo H. et al., 2020, Nat. Ecol Evol., 4, 12, 1639
13. Eukaryotic virus composition can predict the efficiency of carbon export in the global ocean, Kaneko, H. 2021, iScience, 29, 24, 102002
14. Discovery of viral myosin genes with complex evolutionary history within plankton, 2021, Kijima, S. et al. Front Microbiol. 7, 12, 683294
15. Compendium of 530 metagenome-assembled bacterial and archeal genomes from the polar arctic ocean, 2021, Nat Microbiol. 6, 12, 1561
16. Global drivers of eukaryotic plankton biogeography in the sunlit ocean, Sommeria-Klein, G. et al., 2021, Science, 29, 374, 594
17. Giant viruses encode actin-related proteins, 2022, Da Cunha, V. et al. Mol. Biol. Evol. 39, 2, 6527639
18. Restructuring of plankton genomic biogeography in the surface ocean under climate change, Fremont, P. et al. 2022, Nature climate change, 12, 4, 393
19. Cryptic and abundant viruses as the evolutionary origins of earth’s RNA virome, Zayed, A.A. et al., 2022, Science, 376, 6589, 156
20. Functional repertoire convergence of distantly related eukaryotic plankton lineages abundant in the sunlit ocean, Delmont, T. et al. 2022, Cell genomics, 2, 100123
21. Diversity and ecological footprint of global ocean RNA viruses, Dominguez-Huerta, G. et al. 2022, Science, 10, 376, 1202
22. Genomic evidence for global ocean plankton biogeography shaped by large-scale current systems, 2022, Richter, D.J. et al., Elife, 3,11, 78129
23. Mirusviruses link herpes virus to giant viruses, Gaia, M. et al. 2023, Nature, 616, 7958, 783
24. Linking satellites to genes with machine learning to estimate phytoplankton community structure from space, El Hourany, R,. et al. 2024, EGU Ocean Science, 20, 1, 217
25. Complex genomes of early nucleocytoviruses revealed by ancient origins of viral aminoacyl-tRNA synthetase, Kijima, S. et al., 2024, Mol. Biol. Evol. 2,41, 8, 149
26. In situ imaging reveals the biomass of giant protists in the global ocean. Biard, T. et al. Nature 532, 504–507 (2016). https://doi.org/10.1038/nature17652
27.Biological and physical influences on marine snowfall at the equator. Kiko, R. et al. Nature Geosci 10, 852–858 (2017). https://doi.org/10.1038/ngeo3042
28. Baudena, A.et al. The streaming of plastic in the Mediterranean Sea. Nat Commun 13, 2981 (2022). https://doi.org/10.1038/s41467-022-30572-5.
27. Scales BS. Et al. (2021). Cross-Hemisphere Study Reveals Geographically Ubiquitous, Plastic-Specific Bacteria Emerging from the Rare and Unexplored Biosphere. mSphere 6:10.1128/msphere.00851-20. https://doi.org/10.1128/msphere.00851-20.

Institutional Legacy

The exceptional results of OCEANOMICS led the CNRS to propose the creation of a Research Federation. In 2018, the GOSEE Federation (Global Ocean Systems Ecology & Evolution) was launched, directed by OCEANOMICS coordinators (C. de Vargas, Chris Bowler, Patrick Wincker). GOSEE integrates 18 institutions, including CNRS, CEA, PSL, SU, EMBL, and the Tara Ocean Foundation. GOSEE continues holistic exploration of marine ecosystems, aiming to understand fundamental self-organization mechanisms of life across space and time at the ecosystem scale, and integrating this knowledge into Earth system models.

Future Programs

Building on OCEANOMICS, several large-scale programs were developed, including:

• The EU project AtlantEco (2020–2024, €15 million): Meso-scale Atlantic Basin ecosystem assessment.
• Plankton Planet: Global, long-term cooperative oceanography.
• TREC (2023–2024, €15 million) and EU project BIOcean5D (2022–2026, €18 million): Fine spatio-temporal gradients in land-sea ecosystems.