Projet Life Intégré Marha. Etat de conservation de l’habitat d’herbiers de zostères. Bilan d’activités de l’Ifremer pour le volet côtier- Rapport Final

This document constitutes the final report of the LIFE Marha project dedicated to seagrass meadow habitats. The study is structured around two main objectives: (i) improving understanding of the functioning and dynamics of seagrass meadows and their associated faunal communities, and (ii) developing indices to assess their conservation status in relation to their resilience to disturbances. The work is based on an integrated biogeographical approach aimed at characterizing the conservation status of meadows formed by the two seagrass species, Zostera marina and Zostera noltii, and their responses to anthropogenic and environmental pressures. The research was conducted at four study sites along the English Channel, Atlantic, and Mediterranean coasts (Baie de Lancieux, Golfe du Morbihan, Bassin d’Arcachon, and Étang de Thau). It combines mapping of seagrass distribution, quantification of key ecological functions, development of indicators, and modeling of meadow dynamics, with projections highlighting contrasting responses of the two species to climate change.