Main lipid classes in some species of deep-sea corals in the Newfoundland and Labrador region (Northwest Atlantic Ocean)

摘要

Corals contain large quantities of lipids in their tissues; these lipids may be either structural or for storage. Little information is available about the lipid content of deep-sea corals, as well as ratios of main lipid classes. In this study, lipid percentages of 81 deep-sea specimens were measured and the presence of six major classes, including sterols (STEROLS), free fatty acids (FFA), triacylglycerols (TG), monoalkyldiacyl glycerol (MADAG), wax (WAX), and sterol esters (SE), was assessed. Deep-sea corals had fewer lipids than their shallow water counterparts. Decision-tree analysis revealed a link between coral groups and total lipid percentages, showing that species within the same group were characterized by similar lipid amounts. Depth did not seem to impact the total lipid percentages, suggesting that deep-sea corals adapt to the differential access to food by changing the proportion of lipid classes while maintaining equivalent lipid levels. In deep-sea species, similar to their shallow water counterparts, energy seems to be stored as neutral lipids (wax esters and triacylglycerols), with the notable difference that a high proportion of MADAG is present. These compounds are less rich in energy than TG. Depth trends were found for FFA, TG and SE with an increase in percentages after 800 m suggesting a potential need for storage due to decreased food availability. A subsequent decrease after 1,100 m was observed for FFA and TG but a more detailed investigation is warranted as the number of specimens acquired from these depths was less than 20. It is nonetheless a surprising result as increased storage is expected when food sources are sparse.