Continuous reproduction in the Indo-Pacific sea urchin Echinometra mathaei at Rottnest Island, Western Australia

Abstract

Eleven gonadal samples of Echinometra mathaei were taken between April 1965 and June 1967 from Rottnest I., Western Australia, and analysed histologically. Rottnest I, is near the southern distributional limit of this widespread Indo-Pacific echinoid. All stages of gametogenesis were present in most samples, and little seasonal change in reproductive activity could be detected. The lack of synchrony among different individuals and the presence of mature gametes in every sample indicate that the population of E. mathaei at Rottnest I. reproduces continuously. The relatively high sea temperatures that prevail at Rottnest I. during the winter probably contribute to the conditions that permit reproduction to occur throughout the year.