Reproductive cycle of Tagelus plebeius(Bivalvia) in the Ceará river estuary, Northeast of Brazil

Abstract

The bivalve Tagelus plebeius is an infaunal and eurihaline species found mainly in tropical intertidal environments. Although there are studies on the reproductive cycle of bivalves, there is still little research on the reproductive biology of most species found on the Brazilian coast, which are important for the balance of these ecosystems and represent a complementary economic activity or of subsistence for artisanal fishermen. The reproductive cycle of T. plebeius was described from a population located in the Ceará river estuary, in the municipality of Fortaleza, Ceará, Brazil. During 15 months (April/2006 to June/2007), 450 specimens were collected and the gonads were examined by routine histology. The stages of gametogenic development were defined with the following phases: Follicular Organization (OF), Proliferation (P), Maturation/Initial Elimination (M/E), Advanced Elimination (EA) and Cellular Atresia (AC) for both sexes. The species has a continuous reproductive cycle, presenting mature and spawned specimens throughout the year. However, periods of higher gametes release were observed in the second half of the year. Among the factors that would be influencing the reproductive cycle of T. plebeius in the Ceará river estuary, salinity seems to be the main one, since a significant correlation was found between this factor and the phases Maturation/Initial Elimination and Cell Atresia.