The French Ecosystem and Ecosystemic Assessment (EFESE) is a programme initiated in 2012 by the Ministry of Ecology. In the context of this national ecosystem assessment, an assessment of marine and coastal ecosystems and ecosystem services was carried out between 2015 and 2018 by a "Marine WG" driven by IFREMER and the University of Brest (UBO), with the support of the French Agency for Biodiversity (AFB). This document provides a synthesis of the study performed by the "Marine WG" for the EFESE programme.