Résumé
Environmental impact assessment (EIA) studies for offshore wind farm projects endeavour to consider the sensitivity of ecological compartments (benthos, fish, birds and marine mammals) to potential pressures/changes occurring in the ecosystem structure and functioning. EIA is expected to be conducted considering an integrated ecosystem approach, which is still a target to reach. In this context, and as a complementary approach to the traditional impact assessments, the objective of the ANR TROPHIK project is to develop an integrated ecosystem approach using several modelling tools for a holistic consideration of the food web. Here, we take into account the case of the Courseulles-sur-Mer offshore wind farm project located in the Bay of Seine. In this project, the potential impacts associated with this planned offshore wind farm are modelled. A model of the food web at the site of the construction was built to test possible reef- and reserve-effects, and to investigate the usefulness of Ecological Network Analysis (ENA) indices in the assessment of ecosystem health state. After the installation of the wind farm, our model showed that the ecosystem witnessed a change in its functioning mainly due to the important increase of the biomass of bivalves with the reef effect related to the installation of hard structures for the OWF. To go further into the integration of these results, we enlarged the description of the ecosystem functioning from a local to a larger spatial scale, where the initial zone was extended to the whole Bay of Seine using a spatial model. Different scenarios were built to test how the association of cumulative impacts, from climate change to fisheries, could affect the ecosystem. Finally, we propose a combined food-web and social network modelling approach to the Courseulles-sur-Mer model. The objectives of this latter analysis are to construct a decision-making process focusing on the network of actors involved, and to couple these social and ecological networks into a qualitative common model for a better understanding of the social-ecological system. Our approach aims to contribute to sustainable development through the analysis of interactions between the different categories of stakeholders groups, and can be applied in other offshore wind farm implementation in European waters.