Distribution of Scleractinia (Madrepora oculata and Lophelia pertusa) reported between 1995 and 2013 in the French Mediterranean Sea

In the Mediterranean deep-sea two scleractinian species, Lophelia pertusa (= Desmophyllum pertusum) and Madrepora oculata, make up the dominant structure-forming corals. The Lacaze-Duthiers canyon is the only French Mediterranean canyon where the two species L. pertusa and M. oculata have been observed living together in large quantities, the situation generally described for the biocoenosis of cold-water corals (CWC). In this canyon large colonies (more than 40 cm) of both species of scleractinians were observed at depths ranging from 246 m to 541 m at the head of the canyon and its western flank. The second canyon is the Cassidaigne canyon, where M. oculata seems to be the only structure-forming scleractinian there. The largest concentration of M. oculata colonies was observed on the west flank of the canyon along a crest at depths ranging from 200 to 210 m. Mature M. oculata colonies attained heights up to 40 cm. M. oculata were observed in three other canyons: Bourcart, Sicié and Var. In the Bourcart canyon, M. oculata was observed on a shelf of hard substratum at 331 m depth. Several single branches protruded from a slab. In the Sicié canyon a 15-cm colony of M. oculata was observed at 255 m depth, while in the Var canyon, three young branches 2 cm long were seen growing at 350 m depth on a wall of hard rock.