Biochemical composition, lipid classes, fatty acids and sexual hormones in the mussel Mytilus galloprovincialis from cultivated populations in south Spain

Abstract

The mobilization of nutrients and sexual hormone changes during the reproductive cycle of the Mediterranean mussel (Mytilus galloprovincialis), as well as sex related differences have been assessed using adults brought from the field. Metabolites (glucose and glycogen) and lipid composition were determined in the mantle and digestive gland. Moreover, glucose and aminoacids in hemolymph have also been measured. Glucose and glycogen values were lower in ripeness stage in both sexes and tissues analyzed as well as glucose in hemolymph. Glucose was mobilized during sexual maturation to be accumulated as glycogen, which was used as an energy source explaining the low levels in ripeness stage. Lipid content enhanced with ripening in the female mantle while in the digestive gland increased at the beginning but decreased at the end in both sexes. These results suggested the accumulation of lipid for larval development in eggs as well as the energy source during gametogenesis. Triglycerides and phospholipids were the major lipid components in both sexes and tissues assessed, showing several changes mainly in males. Increasing levels of n-3 polyunsaturated fatty acids (PUFA) during gonad maturation mainly due to 22:6n-3 (DHA), have been also observed.Total lipids were higher in females than in males, while triglicerides dominated in females and phospholipids in males. The main fatty acids in both sexes were 16:0, 20:5n-3 (EPA) and DHA. Females showed higher percentages of monounsaturated fatty acids (MUFA) and lower level of saturated fatty acids (SAFA) than males. Sexual hormones have also been analyzed and changes in progesterone and 17-β estradiol during gonadal development have been detected in both sexes.These data will help hatchery managers to determine the best nutritive strategy for producing large quantities of mussel seed.