Effects of Microalgal Diets on Growth, Development and Health Condition of Holothuria scabra Larvae

Abstract

The study assessed the effect of using different microalgal diets on the growth, development, and health condition of Holothuria scabra larvae. Larvae were fed single diets (Chaetoceros muelleri, C. calcitrans, and Isochrysis galbana) and mixed diets Cm+Ig (50% C. muelleri and 50% I. galbana) and Cc+Ig (50% C. calcitrans + 50% I. galbana). On days 3 to 8, larvae fed C. muelleri and Cm+Ig consistently showed better performance than the larvae fed I. galbana alone and the unfed larvae. However, larvae fed C. muelleri alone or in combination with I. galbana had closely similar results to those fed with C. calcitrans and CC+Ig. Larvae fed C. muelleri, Cm+Ig, C. calcitrans, and CC+Ig developed late-auricularia with hyaline spheres from days 9 to 13. Neither larvae fed I. galbana alone nor unfed larvae developed any late auricularia with hyaline spheres. However, only larvae fed with C. muelleri followed by Cm+Ig showed greater percentage of late-auricularia with hyaline spheres compared to the other diets. In terms of size of hyaline spheres, those fed with Cm+Ig had the largest size compared to the other fed algae. Competent doliolaria was first observed on Day 11 in Cm+Ig, although C. muelleri fed larvae had greater percentage of doliolaria on day 16-17, closely followed by Cm+Ig fed larvae. In conclusion, the study showed C. muelleri alone or in combination with I. galbana were the most effective diets for rearing of H. scabra larvae. However, it was suggested to use C. muelleri in combination with I. galbana, for it produced the largest size of hyaline spheres in late-auricularia, which was an indicator of good health of larvae.