Gonadal Development and Reproductive Cycle of the Boring BivalveBarnea Da Vidi(Deshayes, 1874) in Hampyeong Bay, Korea (Bivalvia: Pholadidae)

Abstract

This study describes histologically the reproductive cycle of Barnea davidi inhabiting Hampyeong Bay on the western seashores of Korea. A total of 578 B. davidi, collected from February 2010 to January 2011 with a shell length of 89.5 ± 7.7 mm and a total weight of 47.5 ± 13.7 g, were used for analyses. The sex of B. davidi was distinguishable by both the ovary and testis, which were contained in multiple gametogenic follicles. The gonads displayed histologically definitive seasonal changes. Although the sex ratio (female to male) was 1:1.32 (n = 229:303), the proportion of males increased as the shell length increased. The gonad index (GI) of both males and females was the highest in May, and was the lowest in November for females and in December for males. The pattern of changes in the GI was similar to the pattern of seasonal changes in gonadal tissues and water temperature. The condition index was highest in April and lowest in October. The correlation between the pattern of monthly changes in condition index and the monthly changes in GI and development of gonads was low. The main spawning period of B. davidi was June to July, and the reproductive cycle was divided into the inactive stage (November to December), early active stage (January to March), late active stage (March to May), ripe stage (May to June), and the spent and degenerative stage (July to October).