Fecundity and Reproductive Effort in the Blue Mussel (Mytilus edulis), the Sea Urchin (Strongylocentrotus droebachiensis), and the Snow Crab (Chionoecetes opilio) from Populations in Nova Scotia and Newfoundland

Abstract

Fecundity varies from year to year in blue mussels (Mytilus edulis) from Petpeswick Inlet, N.S., and from Bellevue, Nfld. This observation is consistent with recent theory that suggests that reproductive effort (that proportion of the energy budget allocated to reproduction) should be variable in animals such as marine bivalves that are unable to "predict" the quality of the environment for their juveniles. Estimates of fecundity in the sea urchin (Strongylocentrotus droebachiensis) and the snow crab (Chionoecetes opilio) are also presented. Reproductive effort increases with advancing age in the three species of invertebrates studied, although in the mussel the transition from growth to reproduction is more gradual than it is in the sea urchin or the female snow crab, which exhibit early growth and delayed reproduction. The degree to which the growth and reproductive phases are separated in each species may be determined in part by the predictability of the food supply. The allocation of resources primarily to growth rather than to reproduction in young (small) individuals may be seen as a response to selective pressure resulting from higher mortality and from competition. Key words: growth, production, reproductive strategy, energy partitioning, marine invertebrates, gametes