Seasonal changes in reproductive activity and biochemical composition of the razor clam Sinonovacula constricta (Lamarck 1818)

摘要

The reproductive cycle and seasonal variations in biochemical composition of the razor clam Sinonovacula constricta (Lamarck) from the Yellow River delta in China were investigated from April 2007 to March 2008 in relation to environmental factors. Histological analysis indicated that the gametogenesis of the S. constricta comprised two phases: a resting phase (February-May) and gametogenesis, including ripeness and spawning, during the rest of the year. Gametogenesis of S. constricta began in June-July and was completed during September-October when food was abundant. A significant decrease in the glycogen content of all tissues both in the female and male during sexual maturation suggests that carbohydrates play the most important role in reproduction of this species. The protein and lipid content increased in association with the gametogenesis in the female gonads, indicating that they are the major organic component of oocytes. Conversely, the protein and lipid decreased in the male gonads and other tissues, demonstrating that they also support reproduction after the glycogen is depleted. The RNA/DNA ratio is a valuable indicator of maturation both in the female and male. The results obtained in this study provide useful information for developing management strategies of S. constricta populations in this area, and for optimizing the hatchery-based seed production.