Possible seasonal variation of the fatty acid composition from Melanopsis praemorsa (L., 1758) (Gastropoda: Prosobranchia), from southeast Anatolia, Turkey

Abstract

Possible seasonal variations of the fatty acid composition (neutral lipid, phospholipid, and total lipid content) of the freshwater snail Melanopsis praemorsa were investigated over the course of a year. Snail body lipids were fractionated by thin layer chromatography. Fatty acid composition of total body lipid, phospholipid, and neutral lipid of whole snail and total lipid of their algal food were analyzed by capillary gas chromatography and gas chromatography-mass spectrometry. The most abundant fatty acids were C16:0, C18:0, C16:1\omega7, C18:1\omega9, C18:2\omega6, and C18:3\omega3 acids in the lipid analyses of the snail and in its food. Odd-numbered fatty acids and C20 polyunsaturated fatty acid structures were confirmed by gas chromatography-mass spectrometry. Some differences were found in the percentages of phospholipid and neutral, total, and algal lipid. It is proposed that possible seasonal variations in the snail lipids are related to temperature: a positive correlation between the level of \SigmaSFA (total saturated fatty acids) in total body lipid, phospholipid, and neutral lipid fractions of the snail and temperature was observed, whereas \SigmaMUFA (total monounsaturated fatty acids) levels were negatively related with temperature. On the other hand, there were fluctuations in the concentrations of \SigmaPUFA (total polyunsaturated fatty acids) in all analyses. In algae, maximal \SigmaSFA, \SigmaMUFA, and \SigmaPUFA levels were registered in summer, spring, and winter, respectively. In addition, C18:2\omega6 acid percentages in winter and autumn were significantly high in the algae.