Résumé
The development of offshore windfarms (OWFs) plays a crucial role in the energy transition to provide a sustainable source of renewable energy and achieve decarbonisation targets. However, the ecosystem effects of this expansion remain largely unexplored. This study explored the potential impacts of OWFs in the Eastern English Channel using a multispecies, individual-based model. The main objective of this work is to improve the evaluation of the ecosystem effects of OWFs by considering multiple pressures in a single modelling framework and analyse the ecosystem response under different scenarios of OWF deployment and fishing strategies. This study is an application of an OSMOSE model which represents the main processes of the life cycle of high trophic level species. The model is based on opportunistic predation and spatial co-occurrence between a predator and its preys. This application was calibrated to reproduce observed trends in biomass and catches over the period 2002-2022. The emergent properties of the model (e.g., growth, food web structure) were validated to ensure its ecological realism. Four scenarios of OWF deployment were simulated to investigate the ecosystem response of multiple pressures related to windfarms installations: 1/ energy costs minimisation, 2/ exclusion from regulatory environmental protection zones, 3/ minimal limit of distance from the coast and 4/ a balanced scenario combining the previous three scenarios. The scenarios accounted for the following pressures: fishing access restriction, underwater noise, habitat modification, electromagnetic field and changes of plankton communities. Several ecosystem indicators were used to assess the effect of each pressure as well as the combined effect of all pressures under the different scenarios. Furthermore, a focus on biomass and catch based indicators gave more insights on the spatial extent of the cumulative impacts of fishing activities and OWFs in the Eastern English Channel.