Effect of artificial diets containing cartenoid-rich microalgae on gonad growth and color in the sea urchin Psammechinus miliaris (Gmelin)

Gonadal growth and color were examined in the echinoid Psammechinus miliari s when fed diets containing either micro- or macroalgal supplements. Urchin s receiving diets containing the microalgae Phaeodactylum tricornutum and T ahitian Isochrysis sp. showed significantly greater gonad growth at the end of the 12-wk experimental period as compared to urchins fed the artificial diet with no added algae. An improvement in gonad color, compared to the c ontrol, was observed for both treatments receiving microalgae; whereas, tho se fed the macroalgae Laminaria saccharina diet showed no significant impro vement in color. The P. tricornutum diet improved gonad color more rapidly than the other algal diets. These results show that cultured microalgae, in corporated into an artificial diet, have a positive effect on the gonad col or of P. miliaris, with promising implications for commercial echinoculture .