REPRODUCTION AND CYCLE OF GONADAL DEVELOPMENT IN THE MEDITERRANEAN GORGONIAN PARAMURICEA-CLAVATA

Paramuricea clavata (Risso, 1826) is a typical gorgonian species of su blittoral communities found on rocky substrates in the Mediterranean S ea. The reproductive biology of this species was studied from 1990 to 1992 off the Medes Islands (northwestern Mediterranean). P. clavata is dioecious. The sex ratio was 1:1. Oogenesis lasted 13 and 18 mo, begi nning between February and July and culminating in the release of 13 ( SD = 2.2) mature eggs per polyp during the summer (June to July) of th e following year. Maximum egg diameter varied between 400 and 500 mu m . Male gonads appeared in January and ripened in a much shorter time, 6 to 7 mo. Maximum spermary diameter ranged from 500 to 750 mu m. Male gonadal volume per polyp was larger than female gonadal volume. P. cl avata is a perennial, iteroparous species. Reproduction was synchronou s each year. Over the 3 yr study period spawning took place during 2 d iscrete week-long periods in June and July. Spawning occurred at the e nd of May coinciding with increasing water temperature and correlated with the lunar cycle wherein spawning also occurred 3 to 6 d after the full moon or the new moon. Spawned eggs adhered, through the action o f a mucous coating, to the outer surfaces of the female colonies. Embr yonic development in P. clavata was relatively uncommon. Embryogeny (t otal and equal cleavage) and final maturation of the planulae took pla ce among the polyps. On leaving the surface of the colonies, larvae im mediately settled on the surrounding substrate. Asexual reproduction w as negligible and the maintenance of the population is based on sexual reproduction.