Temperature effects on periodicity and embryology, with observations on the population genetics, of the aquacultural echinoid Heliocidaris tuberculata

Abstract

Since the price for sea urchin roe is seasonal, echinoid mass production should be timed according to market fluctuations. To this end, the fertilization and development of H. tuberculata, a species producing over 60 g of roe per individual, were studied seasonally at different temperatures. The optimum temperature for both fertilization and development varied from month to month as adult reproductive periodicity, fertility and larval developmental success were related to the seasonal ocean temperature. Observations on the population genetics of H. tuberculata revealed that populations were genetically undifferentiated with no evidence for separate sympatric or allopatric races, subspecies or species which may have been morphologically indistinguishable had they existed. Consequently, geographical variations in reproductive behaviour observed between locations were probably caused, not by genetic differences, but by localized nongenetic adaptation to prevailing temperatures.