Marine spatial planning to solve increasing conflicts at sea: A framework for prioritizing offshore windfarms and marine protected areas

Direct and indirect anthropogenic pressures on biodiversity and ecosystems are expected to lower the provided ecosystem services (ES) in the near future. To limit these impacts, protected areas will be implemented as part of the Post-2020 Global Biodiversity Framework. Simultaneously, as an answer to climate change, renewable energies are being rapidly developed on a worldwide scale, leading to a significant increase in space use in the coming decades. Sharing space is an increasingly complex task, especially because of the high rate of emergence of such competitors for space. In fisheries-dominated socio-ecosystems, acceptability of offshore windfarms (OWFs) and marine protected areas (MPAs) is usually very low, partly due to an underrepresentation of fisheries in spatial plans and poor attention to equity in the spatial distribution of restrictive areas. Here we developed a framework with a marine spatial planning case study in the Bay of Biscay represented by the socio-ecosystem of the Grande Vasière, a mid-shelf mud belt spanning over 21,000 km². We collected biological, environmental, and anthropogenic data to model the distribution of 62 bentho-demersal species, 7 regulating ES layers related to nutrient cycling, life cycle maintenance and food web functioning, as well as provisioning ES of 18 commercial species and 82 fisheries subdivisions. We used these spatial layers and a prioritization algorithm to explore siting scenarios of OWFs and two types of MPAs (benthic and total protection), aimed at conserving species, regulating and provisioning ES, while also ensuring that fisheries are equitably impacted. We demonstrate that equitable scenarios are not necessarily costlier and provide alternative spatial prioritizations. We emphasize the importance of exploring multiple targets with a Shiny app to visualize results and stimulate dialogue among stakeholders and policymakers. Overall, we show how our flexible, inclusive framework with particular attention to equity could be an ideal discussion tool to improve management practices.