Growth Rate Assessment of Alcyonacean Sarcophyton glaucum from Northern Hurghada, Red Sea, Egypt

Abstract

Eighteen specimens of the soft coral Sarcophyton glaucum have been collected and tagged to determine the growth rate using the weight variations technique and to investigate the reproductive season histologically. Six colonies were totally weighed and 12 fragments (produced from three colonies) were marked and weighed. Some samples showed sever shrinkage that lead to death. The maximum semiannual growth rate was recorded in summer (30.05 gm/6 m). The average monthly growth reached 3.95 gm/month. Many factors affect the growth rate such as water currents, turbidity, sedimentation, temperature and reproduction process. The studied species is a dioecious species (unisex), where the Autozooid polyps are the reproductive organs while siphonozooids are sterile. Female gonads were observed to develop at late July before male gonads which began at late September. Larvae releasing started at late January and the gonads are completely spawned in February. Fertilization occurs internally to form planulae larvae which librated completely in February. The oogenesis exhibited prolonged about 23 months, which gave rise to oocytes of different developmental stages in female colonies at any given time, and a spermatogenic cycle of only 10 - 12 months.