28 A Cold-Water Coral Habitat in La Fonera Submarine Canyon, Northwestern Mediterranean Sea

Abstract

Based on remotely operated vehicle video imaging, we describe a cold-water coral habitat in La Fonera canyon head (northwestern Mediterranean Sea) and the human impacts which threat this habitat. The dominant cold-water coral species is Madrepora oculata along with Dendrophyllia cornigera. The first occur on highly sloping rocky outcrops most frequently between 180 and 300 m water depth, being the largest colonies those protected by topographic overhangs. Predictive modelling accounting for terrain morphology and positive observations indicates that cold-water coral habitat extent should span over many areas of the canyon head, but M. oculata is mostly absent in the canyon branches incised closer to the coastline. This could be a consequence of an excess of sediment arrival during eastern storms. Daily trawling activity also results in enhanced sediment fluxes, which could account for some M. oculata colonies partially covered by fine mud in the eastern wall of the canyon. Recent physical damage is also observed at specific locations.