Analysis of ecological compensation as an instrument of internalization and fight against the erosion of marine biodiversity: illustration by offshore wind power.

Summary The installation of renewable marine energies is carried out in compliance with French environmental legislation. The Avoid-Reduce-Compensate (ERC) sequence is thus applied in order to achieve no net loss of biodiversity. The objective of this thesis is to question the effectiveness of this sequence, and more particularly that of ecological compensation, as an instrument for internalizing and combating the erosion of marine biodiversity. A qualitative empirical approach was thus implemented to (i) identify the ecological and societal factors as well as their theoretical characteristics that should allow offsetting to achieve the objective of no net loss of biodiversity and (ii) check whether these conditions are verified in practice in the case of offshore wind power in Europe and France. The analysis highlights the legal, institutional, methodological and societal challenges to be met in order for ecological offsets to achieve their objective. Based on this observation, a multi-criteria evaluation is proposed in order to strengthen the avoidance and reduction stages and finally to better define the needs of ecological compensation at sea. The analysis also highlights a shift from compensation based on strict ecological equivalence to compensation based on relaxed ecological equivalence. Offsetting actions tend to be more general and/or more directed towards ecosystem services than towards ecosystem components. Combined with accompanying measures, they can help facilitate the social acceptability of a development project.