Abstract
Temperature tolerances of the early development (up to 4-arm pluteus) of Echinometra mathaei were investigated at 16-34°C. The critical lower and higher temperatures for embryonic development were 16 and 34°C, respectively. At these two temperatures, 100% of the embryos showed abnormality within 48h after incubation. The lower and higher temperature for development of healthy embryos and larvae were 19°C and 31°C, respectively. The developmental times from the 2-cell to early larval stages showed significant differences among 19 to 31°C. At 19 and 31°C, the embryos reached in healthy 2-arm pluteus stage in 72 and 26h after incubation, respectively. The larval growth performance and relative growth ratios of the different organs of 4-arm larvae showed that they were able to tolerate a wide range of temperature without any abnormality. The present findings will be useful for elucidating the possible mechanisms of larval dispersal, as well as the distribution of this sea urchin in various marine locations worldwide.
