Does the Fatty Acid Composition of Greenland Halibut Eggs Matter for Hypoxia Tolerance?

Greenland halibut (Reinhardtius hippoglossoides) eggs are subjected to low oxygen levels in the deep waters of the Estuary and Gulf of St. Lawrence during their development. The aim of this study was to determine the influence of different levels of dissolved oxygen (DO) on the fatty acid (FA) composition in Greenland halibut eggs. Fertilized eggs from three females were exposed to four DO levels: severely hypoxic (10 and 20%sat [percent saturation]), moderately hypoxic (35%sat), and normoxic (100%sat). The FA composition was determined at 14, 17, and 21 days post fertilization (dpf) to investigate the effect of DO levels and female origin on changes in biochemical composition at different developmental stages. The most abundant fatty acids in the polar lipid fraction of eggs were docosahexaenoic acid (DHA) and eicosapentaenoic (EPA) (26 and 22%, respectively), while C16:0 and C18:1 n-9 were the most abundant (15 and 19%) in the neutral fraction. DO had a significant effect on FA composition only at 14 dpf: DHA was significantly higher at severe hypoxia (20 and 10%sat), suggesting a possible adaptive mechanism for increased membrane fluidity.