Changing fatty acid profiles over a depth gradient in the Arctic skate (Amblyraja hyperborea)

Fish have evolved numerous adaptations to cope with the unique biological stresses of living in the deep ocean. In September 2012 and 2013, deep-sea Arctic skates ( Amlyraja hyperborea) were collected from the Canadian Beaufort Sea along a depth gradient ranging from 500-1515 m. Total lipids, lipid classes, and fatty acid profiles of both liver and muscle tissue were compared at various depths. The goal was to expand on previous biochemical depth-related patterns. Both liver and muscle samples exhibited no significant differences at any depth for total lipids nor any lipid class proportion. Liver samples showed significant differences among depths for numerous fatty acid proportions. The saturated fatty acid myristic acid (14:0), and polyunsaturated fatty acids eicosapentaenoic (EPA; 20:5ω3) and docosapentaenoic (ω3DPA; 22:5ω3) all decreased from shallow to deeper depths along a gradient. In turn, monounsaturated fatty acids oleic (18:1ω9), octadecenoic (18:1ω5), and erucic (22:1ω9), increased from shallow to deeper depths. Muscle samples exhibited significant differences among depths for two fatty acids, stearic (18:0) and 22:5ω3 which drove the difference between the most shallow and deepest depths. Our data show that intraspecific changes exist for a deep-sea Arctic elasmobranch, adding to previous research showing adaptations associated with pressure and energy metabolism.