Temporal variation in the reproductive cycle of Mytilus edulis L. (Bivalvia, Mytilidae) from localities on the east coast of the United States

The reproductive condition of seven latitudinally separated populations of the mussel Mytilus edulis on the east coast of the United States was determined using histological analysis and stereology. Differences in the timing of various phases of the gametogenic cycle among populations did not have any discernible latitudinal trend. Two populations at the same latitude on Long Island, N. Y. had the greatest temporal differences observed in gametogenic cycle, with summer reproduction maxima separated by a 3-month interval. There was no difference in the water temperature regime between these two habitats and thus the rate of gametogenic development was not a constant function of temperature. The observed differences in the gametogenic cycle were attributed to temporal and quantitative differences between habitats in the energy content of the mussel's food supply.