Nghiên cứu một số đặc điểm sinh học sinh sản cầu gai đen Diadema setosum (Leske, 1778)

Abstract

Reproductive characteristics of black sea urchin Diadema setosum was studied during the period of April 2016 to April 2017. A total of 632 specimens of black sea urchin were collected from the intertidal reef at Hon Son, Kien Giang province, Viet Nam. Monthly data collection showed that the reproductive cycle of black sea urchin was seasonal dependence. The highest gonadosomatic index (GSI) of black sea urchin was found in June (16.10±7.70), but no differ significantly with those GSI occurring from April to July. The lowest GSI was found during the period of September to December and remain low until March next year. The data suggested that spawing season of animal may occur from May to August yearly. Length-weight relationship of black sea urchin (n=632) was W = 0.48L2.84 with the value of regression co-efficient r2 = 0.93. Histology analysis also confirmed that most of the gonad (>70%) of black sea urchin collected from April to July reached the maturity stage (stage IV) and 5 different stages development of the gonad were also observed. These are resting, recovery, growing, pre-matured and matured stages. The absolute fecundity is GSI and size dependence of black sea urchin. The absolute fecundity was estimated about of 7.1 million eggs/ind. (72.9 g). The gonad of black sea urchin begin to develop when shell diameter of black sea urchin is greater than 2.5 cm.