First report on the annual reproductive cycle of Cellana grata in a rocky intertidal beach at Ulleung Island on the east coast of Korea

Abstract

The annual reproductive cycle of tropical limpet Cellana grata from Ulleung Island was investigated from May 2013 to April 2014 using histology and gonad somatic index (GSI). Gonad somatic index (GSI) was calculated as the ratio of gonad weight to the total tissue wet weight. Gametogenesis commenced in January and most of limpets showed early development phase with small oogonia (5-10 ㎛) from February to May, although fem females exhibited ripe eggs (60-100 ㎛) in their follicular epithelium. In May, the oocyte diameter increased rapidly, and fully mature eggs (110-170 ㎛) appeared in June. First spawning males and females were observed in June as the surface water temperature reached 19.8℃ and July (22.1℃) respectively. The spawning activity continued until the end of December. GSI and histology indicated that spawning peak of the females in Ulleung Island was August and September. GSI of the limpet varied 18.3 in July to 2.8 in October, suggesting that the spawning completed in September. During November and December, most of the limpets were in spent and resting stages. Our data suggested that C. grata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. Resting phase of the male and female limpets from November to April and such prolonged period of resting could be, in part, explainable by poor food condition in the study site. ight to the total tissue wet weight. Gametogenesis commenced in January and most of limpets showed early development phase with small oogonia (5-10 ㎛) from February to May, although fem females exhibited ripe eggs (60-100 ㎛) in their follicular epithelium. In May, the oocyte diameter increased rapidly, and fully mature eggs (110-170 ㎛) appeared in June. First spawning males and females were observed in June as the surface water temperature reached 19.8℃ and July (22.1℃) respectively. The spawning activity continued until the end of December. GSI and histology indicated that spawning peak of the females in Ulleung Island was August and September. GSI of the limpet varied 18.3 in July to 2.8 in October, suggesting that the spawning completed in September. During November and December, most of the limpets were in spent and resting stages. Our data suggested that C. grata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. Resting phase of the male and female limpets from November to April and such prolonged period of resting could be, in part, explainable by poor food condition in the study site.