Reproduction of the sea urchins Echinometra mathaei and Diadema savignyi on the South African eastern coast

Abstract

The reproductive cycles of Echinometra mathaei and Diadema savignyi on the South African eastern coast were investigated by means of gonad index and histological methods. Both species showed annual cycles, with spawning occurring during the summer months (December to March-April), but the degree of gametogenic synchrony differed markedly between the two species. In D. savignyi, gametogenesis within and between sexes was in close synchrony and there was evidence suggesting that repeated spawning with a monthly rhythm occurred. In contrast, gametogenesis in E. mathaei was poorly synchronized and spawning occurred over an extended period.