Lipid composition of the mussel Mytilus galloprovincialis from the Black Sea: fatty acid-based indices as environmental biomarkers.

Context: Owing to the multiple functions of lipids and fatty acids in organisms, lipid composition can be used as an environmental biomarker of the health status of sentinel organisms in monitoring studies of aquatic ecosystems. Aims: To study the lipid profile of the mussel Mytilus galloprovincialis from the Black Sea and to identify lipid compounds as environmental biomarkers. Methods: Lipid and fatty acid compositions in the gills and digestive glands of mussels were analysed by chromatography. Key results: Membrane-state fatty acid indices in phospholipids were quite stable in all the mussels examined. The fatty acid composition of triacylglycerols is primarily an indicator of the food source for mussels. The selective retention of arachidonic acid as well as the accumulation of non-methylene-interrupted fatty acids in mussels are assumed to be biomarkers of environmental stress. Conclusions: The presence of regulatory mechanisms ensuring the stability of the membrane structure was confirmed in all studied mussels. Implications: The content of minor phospholipid fractions (namely, phosphatidylinositol and sphingomyelin) and the distribution of some fatty acids and their indices among lipid classes in the gills and digestive glands of M. galloprovincialis can be used in the assessment of the health status of sentinel organisms. The lipid composition depends on the mussel size; small mussels have an elevated content of main lipid classes. Bivalves have mechanisms to regulate the fatty acid composition of membrane lipids, including maintenance of a constant unsaturation degree of phospholipid fatty acids. Selective retention of arachidonic acid as well as accumulation of non-methylene-interrupted fatty acids in mussels are assumed to be biomarkers of environmental stress. Contents of minor phospholipid fractions in combination with unsaturated fatty acids can be used for monitoring of the health status of mussels. [ABSTRACT FROM AUTHOR]