Evaluating biological significance of chemical exposure to fish using a bioenergetics-based stressor-response model

We demonstrate how contaminant exposure-response relationships can be integrated with a bioenergetics model to estimate the biological significance of sublethal exposure under fluctuating environmental conditions. The integrated bioenergetics-based stressor-response model (SRM) was evaluated by comparing observed and predicted growth of largemouth bass (Micropterus salmoides) exposed to several dieldrin concentrations and by conducting sensitivity analyses. Predictions of the SRM suggest that energetic effects of exposure of largemouth bass to ambient concentrations of dieldrin in lakes at the Rocky Mountain Arsenal National Wildlife Refuge are not biologically significant because the amount of energy lost by resident fish is small compared with variation in food consumption. Furthermore, influence of dieldrin exposure is small compared with the effects of a natural stressor like water temperature. The SRM provides a general framework for integrating laboratory-derived exposure-response relationships with ecological processes to determine the biological significance of multiple stressors in a natural environment. Comparisons of relative effects of anthropogenic and natural stressors can be used to assess potential costs and benefits of alternative ecosystem management strategies.