Changes in the fatty acid composition of phospholipids in tissues of farmed sea bass (Dicentrarchus labrax) during an annual cycle. Roles of environmental temperature and salinity

We quantified seasonal effects on fatty acid composition of tissue phospholipids in farmed sea bass. Major changes in percent phosphatidylethanolamine and phosphatidylcholine were observed in all tissues between February and March, and the phosphatidylcholine/phosphatidylethanolamine ratio was drastically reduced at this time. Different changes in the fatty acid composition of total phospholipids were observed in all tissues examined. Fish fed all year on the same commercial diet showed a significant correlation between water salinity and percentage of 22:6n-3 in muscle, liver and gill phospholipids, but no correlation was found between percent 22:6n-3 of phospholipids and water temperature. In each tissue, we observed annual variation in the 20:5n-3/20:4n-6 ratio in phospholipids, but maximum and minimum values occurred at different times in each organ. From these results, we conclude that salinity can play a significant role in modulating the activities of enzymes acting on lipid metabolism during their natural circannual cycles.