Meeting Abstract
Environmental conditions can strongly influence growth rates and size at maturity in ectotherms. For commercially harvested species, understanding these environmental effects is necessary for successful management and stock assessment, especially under changing environmental conditions. Previous laboratory and field experiments suggest that temperature affects both intermolt period (IMP) and growth per molt (GPM) in blue crabs. Field surveys suggest that blue crabs reach maturity at larger sizes in cooler areas, and at smaller sizes in warm areas. We investigated the effects of temperature on IMP and GPM in a laboratory experiment. Crabs were collected as megalopae and held in temperature-controlled environmental chambers at two temperatures: ambient water temperature and ambient + 5°C. Ambient water temperatures were based on water temperatures at the collection site. Crabs were fed daily, checked daily for molting, and measured following each molt. Temperature significantly affected both IMP and GPM. Crabs reared at the warmer temperature molted more frequently but grew less at each molt. At a given age (time since metamorphosis), the crabs in the ambient + 5°C treatment were larger, but if compared within a given stage, the ambient treatment crabs were larger. These results suggest that temperature has a significant role in determining growth rates, which may result in temperature-driven shifts in time to maturation and size at maturity. To directly examine these potential effects on a longer time scale, this study will be extended until all crabs reach maturity.
