Effects of dietary microalgae on growth , survival and fatty acid composition of sea urchin

This study investigated the growth, survival and fatty acid composition of sea urchin Paracentrotus lividus larvae fed four microalgal diets: Cricosphaera elongata, Pleurochrysis carterae, Tetraselmis suecica and Dunaliella tertiolecta (control). Larvae were successfully raised to competence for metamorphosis when fed C. elongata, P. carterae and D. tertiolecta diets but significant differences were found in survival rate and development. Larvae fed C. elongata showed 3 times higher survival and 20 % faster development than larvae fed the other two microalgae diets that supported development. In contrast, T. suecica failed to fully support development and larvae stalled at the four arms stage for more than 30 days. The urchin larvae could accumulate long-chain polyunsaturated fatty acids (LC-PUFA) such as docosahexaenoate (DHA; 22:6n-3), eicosapentaenoate (EPA; 20:5n-3) and arachidonate (ARA; 20:4n-6), either by assimilation and retention of dietary fatty acids, and/or synthesis from α-linolenic acid 18:3n-3 and linoleic acid 18:2n-6. Moreover, an accumulation of n-3 LC-PUFA and higher EPA/DHA and EPA/ARA ratios appeared to be associated with improved larval performance. The results indicate that live microalgae species, with appropriate fatty acid profiles are able to improve P. lividus larval performance, ultimately increasing hatchery profitability.