Assessing fatty acid remodelling during embryogenesis in Greenland halibut (Reinhardtius hippoglossoides) exposed to hypoxia

Abstract

Eggs of Greenland halibut (Reinhardtius hippoglossoides) are subjected to hypoxic conditions in the deep waters of the Estuary and Gulf of St. Lawrence during their development. The aim of this study was to determine whether there was potential remodelling of fatty acids (FA) during embryogenesis in eggs exposed to several levels of dissolved oxygen (DO). Fertilized eggs were exposed to four DO levels: severely hypoxic (10 and 20% sat [percent saturation]), moderately hypoxic (35% sat), and normoxic (100% sat). No FA remodelling was observed in eggs submitted to the different DO levels. The most abundant FA in the polar lipid fraction were docosahexaenoic (DHA, 22: 6 n-3) and eicosapentaenoic (EPA, 20: 5 n-3) acids (26 and 22%, respectively), the latter being positively correlated with hatching success. Batches with low hatching success were characterized by eggs with decreased levels of polar EPA and DHA at the end of embryogenesis. Whatever the hatching success, the proportion of FA in the neutral fraction was always significantly lower compared to the polar fraction. Oleic acid (18: 1 n-9) (17%) was the main FA found in this fraction; together with gondoic acid (20:1 n-9), they explained most of the variation in hatching success.