Abstract
As part of the energy transition, the French government is planning the construction of eight offshore wind farms along the Channel-Atlantic coast, including the future wind farm off Courseulles-sur-mer. To date, there is no comprehensive and integrated study of the effects of the construction and operation of these parks on the ecosystem. The main innovation of this thesis was therefore to lay the foundations for an ecosystem approach to Marine Renewable Energies (MRE) through the example of the future Courseulles-sur-mer wind farm. To do this, a combination of modeling tools was used in order to: 1) characterize the functioning and structure of the ecosystem of the site where the park is located; 2) test scenarios of possible evolution of the trophic functioning of the system. Thereby, a food web model and three scenarios were built in order to analyze the consequences of the reef and reserve effect generated by the park on the ecosystem. The indices of the analysis of ecological networks as well as other indices such as the mean trophic level were analyzed in order to characterize the functioning of the system. However, aware that this ecosystem is threatened by multiple pressures, it is necessary to understand how these human activities will interact with each other and what are their consequences on the ecosystem in a context of global changes. Thus, a global vision of the cumulative impacts was also developed thanks to another type of modeling called 'qualitative modeling' or 'oriented digraph'. The results revealed changes in the structure and functioning of the ecosystem after the establishment of the wind farm. The results of these models could be used in the definition of follow-up measures after the installation of the park and in the assessment of the need to put in place compensation measures. Finally, qualitative models could also serve as communication tools with the public and thus allow better ownership of MRE projects.