Mapping of ecosystem services provided by octocorals: a methodological approach

This thesis, conducted in collaboration with Laboratoire d’Ecogéochimie Environments Benthiques (LECOB, SU-CNRS) in Banyuls-sur-Mer, aims to build a set of ecosystem services (ES) indicators and map the multiple ES provided by Eunicella singularis, Paramuricea clavata and Corallium rubrum gorgonians, along the French Mediterranean coast, especially within Natura 2000 sites. ES are the benefits people obtain from ecosystems and are categorized as provisioning, regulating, supporting, and cultural in line with the Millennium Ecosystem Assessment. The assessment and mapping of ES has become an increasingly important instrument for marine ecosystem management, decision-making processes, and Marine Spatial Planning (MSP). In this study, I proposed an operational approach to quantify and map some ES provided by the three gorgonians based on the availability of spatial data in the study area. I developed a set of associated and spatially explicit ES indicators and after collecting, quantifying, normalizing, and mapping the spatial data, I implemented hotspot and richness analyses. Through these analyses, I identified areas where the three gorgonian species provide the most multiple ES. I found a scattered distribution of areas supplying ES with a higher percentage coverage of coldspots (55.2%) and areas with no statistical significance (14.2%), mainly due to data deficiency linked to ES indicators. Despite some technical limitations, it was possible to produce relevant spatial information on hotspots and coldspots distribution of gorgonians ES provisioning in the study area to support the achievement of Natura 2000 network goals. Combining species distribution models with this methodological approach could help address spatial data limitation, while an assessment of the economic value of ES will additionally inform marine management policies. Together, such approaches could help to identify critical areas of priority for conservation and management, and guide MSP.