Influence of one selected Tisochrysis lutea strain rich in lipids on Crassostrea gigas larval development and biochemical composition

International audienceEffects of a remarkably high overall lipid Tisochrysis lutea strain (T+) upon gross biochemical composition, fatty acid (FA), sterol and lipid class composition of Crassostrea gigas larvae were evaluated and compared with a normal strain of Tisochrysis lutea (T) and the diatom Chaetoceros neogracile (Cg). In a first experiment, the influence of different single diets (T, T+ and Cg) and a bispecific diet (TCg) was studied, whereas, effects of monospecific diets (T and T+) and bispecific diets (TCg and T+ Cg) were evaluated in a second experiment. The strain T+ was very rich in triglycerides (TAG: 93-95% of total neutral lipids), saturated FA (45%), monounsaturated FA (31-33%) and total fatty acids (4.0-4.7 pg cell(-1)). Larval oyster survival and growth rate were positively correlated with 18: 1n-7 and 20: 1n-7, in storage lipids (SL), and negatively related to 14: 0, 18: 1n-9, 20: 1n-9, 20: 4n-6 and trans-22-dehydrocholesterol in membrane lipids (ML). Surprisingly, only the essential fatty acid 20: 5n-3 in SL was correlated positively with larval survival. Correlations suggest that physiological disruption by overabundance of TAG, FFA and certain fatty acids in larvae fed T+ was largely responsible for the poor performance of these larvae. 'High-lipid' strains of microalgae, without regard to qualitative lipid composition, do not always improve bivalve larval performance