Ciclo reproductivo de Anadara tuberculosa (Cowerby, 1833) Arcidae) en Bahía Magdalena, México

The reproductive cycle of Anadara tuberculosa (Sowerby, 1833) and its relationship with temperature and food availability in Magdalena Bay, Mexico was studied. Twenty five adult specimens were collected, on a monthly basis, between January 1998 and February 1999. Gonads were processed by routinary histology. The reproductive cycle was divided in five stages: resting, developing, ripe, spawning and spent. The developing stage was found within the interval March-October and December 1998, and also in February 1999. Spawning was observed within intervals: January-April and June-December 1998, reaching the highest frequencies in: January (60%), September (60%), and December (71.4%). Ripeness occurred within periods: January-March and June-December 1998, reaching the highest frequencies in July (70%) and August (57.8%). A significant relationship was found between temperature and ripe stage. The annual mean concentration of chlorophyll a was 2.8 mg m^-3, the lowest concentrations were 0.5 mg m^-3 (January) and 0.8 mg m^-3 (February and December). The highest chlorophyll a rate (9.4 mg m^-3) corresponded to May 1998. A significant correlation was found between specimens in developing stage and food availability. It is concluded that the reproductive cycle of A. tuberculosa exhibits some characteristics of molluscs living in temperate and subtropical waters, because its reproduction occurs during the whole year, although it has two massive spawning periods.