Dynamics of the Reproductive Cycle of Two Cerastoderma edule Populations (Óbidos and Ria Formosa Lagoons) along with Their Nutrient Storage and Utilization Strategy

The reproductive performance knowledge of economically important bivalves is essential to establish better shellfishery management measures and aquaculture programs. The reproductive cycle, as well as the nutrient storage and utilization of two Portuguese Cerastoderma edule populations from Óbidos and Ria Formosa lagoons were characterized by evaluating gonadal development stages, gonadal and condition indexes, as well as glycogen and total lipid content, over several consecutive years. The relationship between reproduction and environmental parameters (sea surface temperature and chlorophyll a) was assessed. The reproductive cycle of both populations of C. edule followed a clear seasonal pattern. The onset of gametogenesis took place in early autumn for both populations, and its evolution coincided with a temperature decrease which progressed throughout the winter. The mature stage was reached in spring, followed by a spawning period during spring and summer, triggered by a rise in temperature. After spawning, both populations progressed to a prolonged inactive stage. The condition index reflected the accumulation and utilization of glycogen, which was considerably higher in the Óbidos population. However, no relationships were found in the reproductive cycle of the species. Total lipids remained similar not only during the gametogenesis period, but also during the spawning period, which may be related to successive and simultaneous gamete production and release.