마이크로네시아 축 환초에 서식하는 흑접패 Pinctada margaritifera (Linnaeus 1758)의 번식리듬

Abstract

We examined the relationship between lunar phases and the reproductive cycle of the black-lip pearl oyster Pinctada margaritifera inhabiting Weno Island, Chuuk Lagoon, Micronesia. We divided the one-month lunar cycle into four phases (first quarter moon, full moon, last quarter moon, and new moon) and measured indicators of maturity (gonadosomatic index, GSI and sex maturation-related genes) and invested the change of gonadal development stage during lunar cycle. As the results, the GSI were higher arounder the full moon phase. Also, the gonadal developmental stages of the Black-lip pearl oyster were identified as ripe stage, spawning stage, and spent stage. The spawning stage was observed during the period offull moon and last quarter moon. In addition, the expression level of DMRT in the male Black-lip pearl oyster was highest during full moon and last quarter moon, but the difference in expression level was not observed in the lunar phase infemales and remarkably lower levels than that in male. On other hands, the expression level of VTG in the female Black-lip pearl oyster was highest, but the difference in expression level was not observed in the lunar phase in males and remarkably lower levels than that in female. The results of this study suggest that the lunar phase change directly affects the expression of sexually matured gonads and sexual maturation in Black-lip pearl oyster.