Influence of temperature variation on embryonic and early larval development of a commercially important tropical sea urchin Tripneustes gratilla (Linnaeus, 1758)

Abstract

The present study investigated the influence of different temperature levels (16, 19, 22, 25, 28, 31 and 34oC) on embryonic and early larval development of the tropical sea urchin, Tripneustes gratilla (Linnaeus, 1758) in a controlled laboratory condition. The critical lower and higher temperature for embryonic development was found to be 16 and 34oC, respectively. Embryos reared in these temperatures exhibited 100% abnormality within 48 h post-insemination. The time required to reach embryonic and larval stages was increased with temperature from 28oC followed by 31, 25, 22 and 19oC. The developmental time of 2-cell to 4-arm pluteus larvae showed significant (p<0.05) differences. The survival (%) of larvae at the prism, 2-arm and 4-arm stages were observed as dissimilar from 22 to 34oC, and the highest values (100% or near 100%) were found at 25 and 28oC. The morphometric measurements from prism to 4-arm pluteus larvae at different temperatures differed significantly (p<0.05). However among the temperatures evaluated, 28oC was found as the best temperature for better growth and development of larvae at all stages. The findings of the study would help to develop captive breeding and seed production programmes for commercial aquaculture of the species.