Integrating populations genetics in the management of Marine Protected Areas: complementary insights from the study of two habitat-forming octocorals in the Catalan Sea

Abstract

Marine Protected Areas (MPAs) are considered as a major tool to buffer the decline of marine diversity caused by global changes. Nevertheless, eco-evolutionary processes maintaining the patterns of biodiversity (e.g. connectivity) are barely considered in the design and management of MPAs. In this framework, our main objective was to characterize the connectivity within and among two existing MPAs in the Catalan Sea. We thus implemented a comparative population genetic study between the red coral, Corallium rubrum, and the red gorgonian, Paramuricea clavata, two habitat-forming species from the coralligenous, which is one of the most diverse but also most threatened Mediterranean communities. We first characterized the spatial genetic structure of each species based on similar hierarchical sampling among three areas within the two MPAs and using two sets of microsatellites. Then, we inferred the underlying processes with particular focus on connectivity and genetic drift. We revealed contrasted spatial genetic structures between the two species with a stronger association between genetic and geographic patterns in P. clavata compared to C. rubrum. This result was explained by a higher connectivity and lower genetic drift acting on P. clavata compared to C. rubrum in accordance with their larval biology. In addition, our comparative approach showed barriers to gene flow likely due to dominant oceanographic currents. Overall, the pattern of connectivity obtained for P. clavata confirm that the two MPAs may be considered as an effective network. At local scale, we propose to target genetically isolated populations of C. rubrum for restoration actions to counteract the negative impact of genetic drift in this species. This study illustrates how comparative population genetics studies could be used to enhance the management of MPAs and accordingly, to improve the conservation of marine biodiversity