Reproductive effort and cost in the bay scallop,Argopecten irradians concentricus

Abstract

Summary Reproductive effort (0.14) and the cost of reproduction (-0.09) of 1-year-old bay scallops, Argopecten irradians concentricus, are greater than for longer-lived iteropar- ous mollusc species of the same age but less than for semelparous species. This agrees with theoretical predictions on the relationships between longetivity, reproductive effort, and residual reproductive value for the maximization of reproductive tactics. For a Florida population (representing the southern distributional limit of the species), the production of 2.8 kJ of gametes requires the catabolism of 19.9 kJ of somatic energy reserves, for a 7.1 cost ratio. Reproductive costs such as these are not included in estimates of reproductive effort and are not considered in energetic terms in cost of reproduction indexes. The relatively high reproductive effort enables A. irradians concentricus to maintain a stable population from year to year at this location in spite of a relatively high cost of reproduction (which may in turn accelerate the senescence of individuals within this population).