ENVIRONMENTAL-CONDITIONS, GROWTH AND PRODUCTION OF ANADARA-SENILIS (LINNAEUS, 1758) IN A SENEGAL LAGOON

Two populations of Anadara senilis were sampled periodically in a lago on of Senegal. Spatfall occurs in summer during the rainy season. Popu lation density decreases from about 50,000 m-2, two months after spatf all, down to 6,750 one year later and 750 after 28 months. The average growth, measured on the surface of the shell, following the umbo rim axis is 0.8 mm per month. The main reduction in growth rate occurs in winter and ends by the deposition of a growth ring. A second growth re duction takes place during the rainy season and sometimes ends by a we ak growth ring. The microgrowth increments are conspicuous and widest during spring equinox. They are not directly related to the tidal cycl e, but it was impossible to determine if they have a tidal or a daily periodicity.