Impacts of offshore wind farm development on marine connectivity along the French metropolitan coast: The GreyCo project

Philippe Cugier¹, Florentine Riquet¹

¹Ifremer, France

The marine environment is naturally a heterogeneous mosaic of habitats, structuring the connectivity of marine species populations. The increase of artificial structures along the coastline and offshore areas (such as dykes, buoys, platforms, wind farms, ports, wrecks...) is modifying the natural landscape: these structures offer new supports that serve as recruitment sites for marine species, playing a key role in the connectivity among populations. Indeed, these artificial structures form new habitats that can act as stepping-stones’, connecting previously isolated populations, lineages or species. This colonization of artificial habitats, and its resulting connectivity, can significantly alter local and regional biodiversity, by modifying species richness. Furthermore, these structures influence genetic diversity, particularly by facilitating hybridization among individuals from divergent populations or even lineages.
With the rapid development of offshore wind farms along French metropolitan coastline, the GreyCo project aims to better understand the interplay between natural populations, harbor communities and those associated with offshore wind development. By integrating population genetics and modelling approaches, GreyCo explores how the installation of offshore wind farms modifies both natural and anthropogenic connectivity networks for benthic populations. Specifically, the project examines the connectivity between populations newly established on wind turbines and those in coastal natural or anthropized habitats, identifying their origins and predicting the broader impacts of offshore wind farms. This knowledge will support sustainable spatial planning and inform strategies for biodiversity conservation in offshore renewable energy contexts.