Pressurised aquaria for the study of deep-water corals

Abstract

A set of four identical pressurised mesocosms is presented, aiming at long-term incubations of deep-water corals, as deep as 3000 m. Care was also taken to enable practical boarding of these instruments on oceanographic ships. Four-month incubations of two scleractinian species (D. pertusum and M. oculata) originating from 800 m depth were achieved at the laboratory (including 3 months at 8 MPa pressure). Two of the aquaria were also operated during a 2-week cruise in the Bay of Biscay, focusing on the same species. Specific requirements for long-term studies are exposed and discussed, emphasizing resistance to corrosion and the possibility to feed fauna without decompression. The first-time long-term incubation of deep-water corals at in situ pressure opens perspectives for future studies, including investigations on deeper corals not yet accessible to laboratory experiments. The use of pressurised mesocosms may be of particular importance, considering the predicted consequences of ocean warming and acidification on the bathymetric distribution of reef-forming deep-water scleractinians.