Bioenergetic costs of heavy metal exposure in yellow perch (Perca flavescens): in situ estimates with a radiotracer (Cs-137) technique

While the flow of energy is understood to determine the growth of organisms and the productivity of ecosystems, little is known about the sublethal ef fect of pollutants on the energetic efficiency of wild populations. We used field estimates of fish growth coupled to in situ estimates of food consum ption rates obtained from the mass balance of a globally dispersed, trophic ally transferred radiotracer (Cs-137) to demonstrate the bioenergetic impai rment of yellow perch (Perca flavescens) from lakes polluted by heavy metal s (Cd, Cu, and Zn). Annual growth increment relative to the total energy bu dget (conversion efficiency) was about three times lower in cortisol-impair ed yellow perch from metal-polluted lakes relative to yellow perch from ref erence lakes (4.2% compared with 10.8%), suggesting that fish exposed to po llutants experienced greater total energetic costs. In addition, metal-poll uted lakes were dominated by adult yellow perch populations and simplified prey bases, suggesting that effects are occurring at multiple levels of bio logical organization. Our in situ bioenergetic approach to toxicity assessm ent provides a measurable and ecologically relevant endpoint for assessing the sublethal effects of pollutants on fish communities.