Environmental Conditions, Growth and Production of Anadara Senilis (Linnaeus, 1758) in a Senegal Lagoon

Two populations of Anadara senilis were sampled periodically in a lagoon of Senegal. Spatfall occurs in summer during the rainy season. Population density decreases from about 50, 000.m−2, two months after spatfall, 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 reduction takes place during the rainy season and sometimes ends by a weak growth ring. The microgrowth increments are conspicuous and widest during spring equinox. They are not directly related to the tidal cycle, but it was impossible to determine if they have a tidal or a daily periodicity.