Influence of microalga lipid composition on the sexual maturation of Mytilus galloprovincialis: a hatchery study

The effect of microalga lipid composition on the reproduction of the mussel Mytilus galloprovincialis has been assessed to determine the best feeding strategy for producing large quantities of mussel seed. Three diets based on two microalgae Isochrysis galbana (clon T-iso) and Chaetoceros gracilis were tested. Besides, hatchery groups were compared with mussels from natural populations. Lipid content and fatty acid profile of digestive gland and mantle of both sexes, eggs and microalgae were analysed and related to sexual maturation. Hatchery groups, specifically the one fed on T-iso, showed better results in reproduction success, and these differences were reflected on tissue and egg lipid composition. Microalga fatty acid profile influenced tissues and sexes, and higher levels of 18:1n-9, 22:6n-3 (DHA) and 18:2n-6 were detected in groups fed on T-iso while higher level of 20:5n-3 (EPA) and 16:1n-7 in groups fed on C.gracilis. Evidence of synthesis capacity of EPA from 18:4n-3 and DHA from EPA is detected comparing their levels and the mobilization between tissues. Egg fatty acid profile was influenced by the female diet, and differences among groups were detected and confirmed by PCAs.