The effect of intertidal habitat on seasonal lipid composition changes in blue mussels, Mytilus edulis L., from the White Sea

The lipid composition of blue mussels Mytilus edulis L. living under different environmental conditions (in the intertidal zone and in aquaculture) was studied to detect origin-related differences in seasonal modifications of lipids, and their fatty acid composition in gills and digestive glands. In early May, the gills and digestive glands of intertidal mussels contained higher amounts of total lipids, chiefly phospholipids and sterols, which appear to perform a protective function as maintenance of membrane integrity. Seasonal modifications in lipid composition of both intertidal and aquaculture mussels were related to environmental factors (mainly low temperature), reproductive processes and food availability. We show that seasonal changes in membrane lipid composition of both intertidal and aquaculture mussels reflect the process of membrane lipid remodelling (namely changes in phosphatidylethanolamine proportion and in the fatty acid composition of phospholipids) required for homeoviscous adaptation in low-temperature conditions. In particular, the unsaturation index and chain fluidity index of phospholipids increased in gills and digestive glands of mussels collected in early May and in November. Similar seasonal changes in the triacylglycerol levels and its fatty acid composition were observed in gills and digestive glands of both intertidal and aquaculture mussels collected in late May and August.