Gametogenesis and spawning in the carpet‐shell clam,Ruditapes decussatus(L.) (Mollusca: Bivalvia), from the Atlantic coast of Morocco

摘要

Abstract.Aspects of gametogenesis of the carpet‐shell clam,Ruditapes decussatus(L.), in two lagoons on the Atlantic coast of north Morocco were studied during December 1986 to February 1988. The clams sampled did not show any sign of hermaphroditism and the percentage of males was 42. The gonads started developing in mid‐winter and were ripe in spring. Successive spawnings and reconstitution of gametes look place simultaneously starting from May up to the end of September. Two major spawning periods were noticed: a partial one in May‐June and a complete spawning in August‐September. From October to December the gonads were at resting stages. In coastal ecosystems where freshwater input is a very important factor, gametogenesis may be affected if clams are exposed to low salinities (less than 15) for prolonged