DS01 - Gestion sobre des ressources et adaptation au changement climatique

ConnEctivity and Resilience of Back-arc Basin hydrothERmal vent commUnitieS – CERBERUS

Submission summary

Hydrothermal vents are ephemeral habitats inhabited by a highly specialized fauna. If connectivity between vent sites is relatively well understood along continuous oceanic ridges, it is a lot less clear for back-arc basins of the western Pacific, despite the increasing threat of deep-sea mining in this specific area. The motion of plates in the West Pacific initiated about 25 Mya has led to species complexes by vicariance, with the progressive opening of the present-day basins spanning over 2-10 My. Since their opening, larval dispersal modeling predicts episodic and unidirectional exchanges between basins. Here, we want to understand the factors that control hydrothermal vent biodiversity between and within basins and in particular the role of connectivity on the resilience of communities. This will allow us to further address with genomic tools the question of the temporal and spatial dynamics of BAB fauna in order to assess its vulnerability to the ongoing anthropogenic pressures. We formed a research consortium to tackle this societal issue with an integrative approach based on the samples that will be collected during an upcoming research cruise on 5 back-arc west Pacific basins. The project is sub-divided into 5 tasks, including the coordination task. The first scientific task will be dedicated to inventory communities using morphological, barcode, and metabarcode approaches and assess geochemical diversity of the vent habitat. Faunal datasets will be used to examine biogeographic patterns within and between basins using co-occurrence networks and to define more precisely the role of geography and fluid chemistry in the partition of the vent biodiversity. The second task aims at estimating levels of gene flow between and within basins for about 10 species (vent-endemic and peripheral) using high-throughput population genomic approach (RAD) and to date vicariant events over the geodynamic history of basins. This task intends to use new and promising population genomics methods (JAFS, distance inference methods based on introgression queue/allelic clines) to disentangle past and present-day connectivity at the appropriate spatial scale. The third task will focus on larval biology and reproduction dynamics of the vent fauna thanks to the sample collection and the use of in situ automatic larval samplers. The origin of recently-recruited individuals will also be determined by elemental fingerprinting of larval shells for species which possess developing embryos in capsules. Finally, information gathered in the 3 tasks will be used to refine a demo-genetic model for exploring scenarios of population connectivity in the face of anthropic perturbations. This knowledge is paramount for the proper management of this peculiar fauna, potentially threatened by the increasing mining effort to exploit metal sulfide deposits in the area.

Project coordinator

Monsieur Hourdez Stephane (Adaptation et diversité en milieu marin)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

AD2M Adaptation et diversité en milieu marin
ISEM Institut des Sciences de l'Evolution de Montpellier
LECOB Laboratoire d'Ecogéochimie des Environnements Benthiques
IFREMER Ifremer Ressources Minerales et Environnement Profond

Help of the ANR 718,457 euros
Beginning and duration of the scientific project: February 2018 - 48 Months

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