Trophic ecology of three deep-sea coral species, interannual comparison using trophic biomarkers

The seabed covers nearly 71% of the Earth's surface, with an area of 362 million km² of which 90% is represented by the deep ocean. In these light-deprived areas, distant from productive
surface waters, reefs formed by a community assemblage of heterotrophic scleractinian corals thrive. However, food resources availability is one of the factors limiting the distribution of deep-sea coral reefs. In this in-situ study, we focus on the species Desmophyllum pertusum, Madrepora oculata and Solenosmilia variabilis which cohabit and share trophic ressources in the Lampaul Canyon off the coast of Western Brittany. Our work aims at describing the use of food resources among these three species over a period of three years. Our results have shown differences in dietary habits among the three species. Although all feed on varied prey, Desmophyllum pertusum and Solenosmilia variabilis preferentially feed on zooplankton while Madrepora oculata predominantly consume phytoplankton. These results highlight the efficient partition of trophic resources within the cold-water coral’s reefs of the Lampaul Canyon.