Reproductive biology of the holothurians from the major communities of the New Caledonian Lagoon

Abstract

The reproductive biology of nine species of aspidochirote holothurians from the major communities of the New Caledonian lagoon has been analysed. The data were obtained from monthly sampling from 1978 to 1982 of their populations on reef slopes and passes for Holothuria nobilis, H. fuscogilva, H. fuscopunctata and Thelenota ananas, in the inner lagoon for Stichopus variegatus, H. scabra and H. scabra versicolor and on reef flats for Actinopyga mauritiana, A. echinites and H. atra. The morphology and anatomy of the gonads and their annual cycle are described. The reproductive cycles, composed of the five phases of gonad growth, maturing, spawning, post-spawning and resting, were determined from the changes in the sexual stages, the gonad indices and the percentage of indeterminate sex. Three main reproductive patterns are recognized, annual cycles with spawning occurring during the warm season or during the cool season and a semiannual cycle. Other population parameters, such as the size of the mature oocytes, the mean size of the individuals at first sexual maturity, and absolute and relative fecundities were calculated and related to the mean size of the species, the taxonomy and the ecology. The reproductive strategies of the species show a gradient that is probably related to the stability of the biotopes, with smaller species living in the more intrable outer reef flats and larger species in deeper lagoon floors.