The reproductive cycle of the oyster Crassostrea gasar/Ciclo reprodutivo da ostra Crassostrea gasar

Abstract

The purpose of this study was to analyze the reproductive cycle of the oyster Crassostrea gasar (= C. brasiliana) in tire field and the laboratory. The reproductive cycle of the animals was evaluated in the field at Sambaqui Beach, Florianópolis, SC (27° 29I8" S and 48° 32I2" W) from May 2008 through November 2009. In July, the animals were in tire resting stage. The early growth stage began in August and was followed by the late growth stage in October. In November and December, the oysters began to enter the mature stage. Females in spawning condition were predominant during these months. The stages of the reproductive cycle were positively associated with temperature (r=0.77, PO.01) and negatively associated with salinity (r=-0.56, P=0.042). These findings demonstrated that increased temperature and reduced salinity influence the reproductive development of Crassostrea gasar. The condition index (CI) of the animals was also associated with tire seawater temperature. The highest values of the condition index were observed during the months when the temperature of the seawater was gradually increasing. A laboratory experiment was performed to test the effect of salinity on the reproductive cycle of the oysters. The experiment was conducted in standardized tanks. The animals were conditioned using two salinities (24[per thousand] and 3496o). The salinity regime influenced the development of tire gonadal tissue of file oysters. A salinity of 24[per thousand] produced greater reproductive development.