These cruises APPEAL ATL 18-1 and 18-2 are part of the first phase  of the ANR APPEAL project, which consists of acquiring ecological data on the site of the future floating wind farm in Groix-Belle-Ile. The main objectives of these campaign requests are (i) the environmental characterization of sites, (ii) the description of the composition, structure and functioning of benthic communities, and (iii) the characterization of the reef effect and the FAD effect generated by the establishment of fixed anchorages. First, the purpose of these campaigns is to define the environmental and ecological reference state (zero state) of the future site for floating offshore wind turbines off Groix, and to acquire spatial data for models and samples for food web analysis (stable isotopes). In a second step, the impact of future OWF devices on fauna and flora will be estimated from instrumented anchorages in order to study the colonization of submerged substrates by sessile organisms (reef effect) and the attractiveness exerted by anchorages on fish (FAD effect).
The impacts on habitats and populations originally present at the pilot site raise three major questions: what effects will OWF devices have on the structure and diversity of habitats and benthic communities? Can we define robust ecological indicators of these changes (MSFD perspective)? What will be the possible changes in the structure (nature, intensity of linkages) of the food web?
The introduction of hard substrates into the water column and on the bottom, in an environment where they were absent, will generate the implantation of sessile organisms. What will be the effects on the functional diversity of the community (changes in dominance, appearance of new species, etc.)? Will these "isolated" populations increase connectivity by "flea leaps" at the metapopulation level, as suggested? What will be the effects on trophic ecosystem functioning on a larger scale? Will the structures play a role as producers of material exported to neighbouring ecosystems? What spatial scale(s) should be considered? (local? regional? other?).
With regard to the FAD effect, will the submerged structures aggregate or create surrounding biomass? Will the possible concentration of fish in these areas have an impact on the benthos by increasing predation? Can this lead to a change in the trophic functioning of the ecosystem?