Growth of post-set oysters, Crassostrea virginica, on high-lipid strains of algal flagellates Tetraselmis spp

Nine microalgal strains from the prasinophyte genus Tetraselmis that were chosen for high total lipid content, and one marine strain of the chlorophyte Chlamydomonas, were compared with Isochrysis sp., strain T-ISO, as diets for oyster spat in a controlled laboratory feeding experiment. Five of these high-lipid Tetraselmis strains supported significantly faster oyster growth than an equivalent ration of T-ISO. Doubling times for oyster weight, volume, and shell height were in the range of 1.5–3 weeks on single daily feedings of the best diets. Tetraselmis strains yielding the most rapid oyster growth contained higher contents of the essential fatty acid 20:5 n − 3 and of the sterols 24-methylcholesterol and/or 24-methylenecholesterol. These data are consistent with our earlier findings that these compounds appear to be deficient in most phytoplankton for optimal growth of Crassostrea virginica spat.