Maeva Gonzalez1, Antoine Carlier1, Nicolas Desroy1, Aurélien Tancray1, Gabin Droual1, Killian Guyomard1, Marine Reynaud2
1Ifremer, France - 2Fondation Open-C, France
In the context of global change and use of renewable energy resources as a solution to reduce greenhouse gas emissions, European offshore wind capacity has quadrupled in Europe over the last 10 years. In France, 45 GW of offshore wind turbines (OWT) are expected by 2050, including the floating technology. While fixed OWT are known to act as artificial reefs and modify local benthic biodiversity, there is a knowledge gap on the interactions between floating OWT and the benthic receptor ecosystem.
In the Velella project (funded by the French State as part of France 2030 operated by ADEME), we investigated how the first French pilot floating OWT FloatGen (located in the Bay of Biscay, 33m depth) was colonized by biofouling and influenced the soft-bottom benthic communities. We described the spatial structure of the epibenthic community on the square concrete floating foundation (36m side; 7m draft), 6 years after its deployment. Biofouling composition was assessed according to depth and wave exposure and compared with general patterns reported for fixed OWT foundations and buoys. Abundance, biomass and biological traits data of epifauna were used to explore the impact of such large floating structures.
Preliminary results show a classic vertical zonation of biofouling with mussels, anemons (Metridium sp.) and alcyonids dominating shallow, intermediate and deeper areas respectively. There is spatial variability depending to the side wall of the float, probably due to the influence of waves and light. This suggests different successional trajectories, linked to variable resistance of fixed species to hydrodynamics and/or variable influence of predation (e.g. sea stars on mussels). We also show a clear influence of biofouling colonizing the float on the structural and functional diversity of soft-bottom benthic communities located below, mainly through the drop-off of shells and faecal pellets by suspension feeders living on the float.
Biography
Currently in the second year of her PhD, Maeva is working on a study of biocolonization and the impact of a floating wind turbine prototype on benthic communities. She is supervised by Antoine Carlier, Nicolas Desroy and Marine Reynaud. Her work includes taxonomy, the study of diversity, food webs and material flows. This conference will give her the opportunity to present her first results, as well as the first quantitative results for this type of artificial reef.