Reproductive studies on Patiriella gunnii (Asteroidea : Asterinidae) in south-western Australia

Abstract

Sea-star radius, gonadosomatic and pyloric indices, oocyte diameters and sperm development in Patiriella gunnii from intertidal rock platforfis near Fremantle, Western Australia, were monitored between November 1983 and June 1985.

The reproductive events in male and female sea-stars were closely synchronized, and pyloric and gonadosomatic indices were inversely related. Both sexes exhibited a sharp peak in gonadosomatic indices (GSI) in March and April 1984, and in March 1985. GSI values declined to low levels in May and June, followed by a slow recuperation in females thereafter. Small and large maturing oocytes occurred together in the ovaries of females exceeding 13-15 mm radius between November 1983/April 1984 and November 1984/March 1985. Large mature oocytes were apparently shed in toto between March and May in each of the two successive breeding seasons. These data suggest that P. gunnii spawns in the late Southern Hemisphere summer through early autumn. Highly motile spermatozoa were usually present in males exceeding 11 mm in radius from at least January through to June. Large maturing oocytes were rarely observed in females less than 13 mm in radius. The pattern of reproductive events in P. gunnii is compared with that of other Patiriella species.