Harmful algal blooms: a threat for sustainability of exploited bivalves? – HABIS

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 national and international research strategies (Paris Agreement, UNESCO). HAB affect coastal ecosystem ecology, structure of marine communities and life-history traits of ecological and economic important species and thus the food web they support and related socio-ecosystems with significant associated costs, of for example more than 800 million euros/year in Europe alone.Often synchronized with the reproduction period of bivalves, these HABs are suspected to be responsible for the recruitment defects of bivalves regularly observed along the French coast. These recruitment anomalies could, in the long term, modify the structure of wild populations and affect aquaculture production, thus the sustainability of the resources of exploited species. Until recently, the HAB species mostly studied were those causing paralytic, amnesic or diarrheic syndromes in humans following the consumption of contaminated shellfish. But some of these species, as well as other so-called ichthyotoxic species (e.g. Kareniacae) regularly observed or emerging on European coasts produce bioactive compounds. Their chemical nature is unknown but recent studies suggest that these compounds are extremely deleterious for marine species.
In a context of global changes associated with HAB intensification and the need to develop aquaculture to support the food needs of a growing world population, HABIS project will analyze the vulnerability of exploited bivalves to regularly blooming or emerging HAB species along French coasts. We will focus on consequences of HAB on 3 life-traits determining bivalve stock renewal: reproduction, development and recruitment of selected bivalve species (WP2&4) and the identification of causative agents responsible for HAB toxicity (WP3). Our funnel-shaped strategy relies first on in vitro large screening of HAB toxicity using bioassays on gametes (developed in HABIS) and larvae (existing) (WP2). The HAB/bivalve pairs for which toxicity is highest are selected for WP3&4. For these pairs, the toxic compounds of HAB will be researched (WP3). Meanwhile, the cellular (flow cytometry, imaging) and molecular mechanisms (transcriptomics, epigenomics) of toxicity on bivalve reproduction and development will be studied by an integrative physiological approach from individual to gene, over a generation and the offspring thanks to a strong experimental force of the consortium (WP4). Results from WP2 to 4 will implement bioenergetic models to prediction purposes (WP4). HABIS will actively participate to public awareness of the consequences of increasing human ecological footprints and global change on the development of HAB and their impacts on human health and marine ecosystems by developing classes, art and communication towards general public and transfer knowledge to stakeholders (WP5).
This multidisciplinary project will bring together biologists, physiologists and chemists, and will also involve some professional partners, such as a private hatchery, the local aquaculture and fisheries committee and artists involved in communications actions. HABIS will participate to a better knowledge on HAB toxicity and their consequences on marine resources, especially on reproduction, a key component of population fitness. This basic knowledge is critical to further determine the vulnerability of molluscan populations in a scenario of global change. HABIS will also participate to a better consideration of HAB phenomenon by public, stakeholders and decision-makers through communication actions and research in environmental law. The approaches used in HABIS will be applicable to other biological models enabling future improvement of management of shellfish resources for sustainability of productive ecosystems.