Thesis defense of Alicia Veuillot from LEP laboratory

Colonisation processes at the peripheries of hydrothermal vents: zones that are potentially targeted for their mineral resources

Please fell free to come and see Monday 24th March 2025 9h30, at Institut Universitaire Européen de la Mer, amphithéâtre "A", Technopôle Brest-Iroise, Plouzané.

In a context of population growth and global overconsumption, deep-sea mineral resources are targeted by industries. It therefore appears crucial to implement management strategies before potential future exploitation. The first step in these strategies is to fill the knowledge gaps we have on the functioning of the ecosystems associated with these resources, and in particular on all the dynamic processes involved in colonisation. This thesis focused on the Snake Pit (SP) and TAG vent fields, part of the French exploration contract area on massive sulfide deposits on the Mid-Atlantic Ridge (MAR). After characterizing the distribution of the fauna associated with the little-studied natural assemblages of Bathymodiolus puteoserpentis mussels of SP, the colonisation mechanisms were experimentally evaluated via the deployment of artificial organic (wood) and inorganic (slate, synthetic sponge) substrata along a hydrothermal gradient from active edifices to nearby peripheries. The results obtained allowed us to observe faunal redundancies between natural communities and those colonising artificial substrata, but also the appearance of wood specialist taxa. The attraction of exogenous fauna on organic substrates, the low colonisation of mineral substrata in an environment where they remain little limiting even in the event of impact, and the important role of hydrothermal activity, greatly limit the restorative potential of artificial substrata in a hydrothermal context. However, this study highlights the interest of using artificial substrata as tools to investigate the mechanisms involved in colonisation processes in deep marine environments.