Gametogenic Cycle of Rangia Cuneata (Mactridae, Mollusca) in Mobile Bay, Alabama, with Comments on Geographic Variation

Stages of the gametogenic cycle of the brackish water clam Rangia cuneata were investigated in Mobile Bay, Alabama, by histological examination of the gonads. Water temperature and salinity measurements were related to the gametogenic cycle and compared to those made in other studies on the same species in different locations. Clams in the early active phase were found from February through April, and those in the late active phase predominated in May. Gonads were ripe from July through September and were partially spawned from September through October. Clams became spent between November and January. Changes in meat, gonad, and total wet weight reflected the stages of the gametogenic cycle, while length of the shells remained nearly constant year round. The gametogenic cycle of R. cuneata in Mobile Bay followed a similar pattern to that observed in clams studied in other locations, except that gametogenesis began earlier, during late winter, and clams became spent earlier in the fall. It is suggested that the interactive effects of temperature, salinity, and nutrients can account for the differences in the timing and length of the stages of the gametogenic cycle between locations.