Isotopic analyses, a good tool to validate models in the context of Marine Renewable Energy development and cumulative impacts

Abstract

As part of the energy transition, the French government is planning Offshore Wind Farm (OWF) constructions in the next decades. An integrated ecosystem approach of two future OWF sites of the Eastern English Channel (Courseulles-sur-mer and Dieppe-Le Tréport) was developed to model the marine ecosystems before the OWF implementation. Such ecosystem models allow simulating the possible reef and reserve effects associated to the presence of the farm, and to character the overall changes in the food-web functioning. This holistic view of OWF effects could be replicated on other sites and form the basis of an ecosystem based management of marine renewable energies. However, to use these models for management purpose, they need to be validated. In order to do so, stable isotope ratios of nitrogen were used for determining the accuracy of the effective trophic levels computed in these two models. Results showed that trophic levels estimated by the two models were consistent with the trophic levels estimated by the independent isotopic data. In the context of OWF development and cumulative impacts analysis, this step of validation of the models is essential for developing their use by management actors and policy makers.