Abstract
The soft coral Scleronephthya gracillimum (Alcyonacea: Octocorallia), a member of family Nephtheidae, is abundant in the southern part of Jejudo Island, Korea. To examine the sexual reproductive pattern, monthly collections and histological studies were conducted from June 2003 to October 2007. The sexual reproductive pattern of the genus Scleronephthya was described for the first time in the present study, which established that S. gracillimum is a gonochoric broadcaster, with the sex ratio of 1:1. The gametogenic cycle was annual, and a difference between female and male colonies was apparent, with biorhythms of 12 and 5-7 months respectively. Gametogenesis and spawning are related to seasonal factors such as seawater temperature and algal blooms. Actual spawning event occurred, and others may have taken place, when seawater temperature attained an annual peak between August and September. The actual spawning occurred in the field at 10 a.m. on September 3, 2006, 4 days before the full moon.
