SEASONAL-VARIATIONS OF LIPID CLASSES AND FATTY-ACIDS IN FLAT OYSTER, OSTREA-EDULIS, FROM SAN-CIBRAN (GALICIA, SPAIN)

Lipid class analyses and fatty acid composition of triacylglycerols and phospholipids were carried out in a wild population of Ostrea edulis over a period of 16 months. Phospholipid was the most abundant class except in September 1989. The low level of triacylglycerols Suggests a scanty food availability. The seasonal cycle of phospholipids, triacylglycerols and free sterols was parallel to that of total lipids. Close to two-thirds of triacylglycerol fatty acids were polyunsaturated (61.8 +/- 6,45%). It is suggested that this lipid class may act as a temporary reservoir of important polyunsaturated fatty acids. Both triacylglycerols and phospholipids were highly unsaturated because of large concentrations of n-3 polyunsaturated fatty acids (PUFAs). The percentage of n-3 PUFAs was always higher than n-6, and n-3/n-6 was considerably elevated. The possible deficiency of;essential fatty acid seems to be compensated by a relatively high proportion of 20:3n-9 fatty acid and non-methylene;interrupted fatty acids. The results reported in this paper appear to show a poor nutritional condition.