Estimating physiological cost of chemical exposure: integrating energetics and stress to quantify toxic effects in fish

Abstract

We present empirical support for a conceptual framework in which chemical contaminants are considered as sources of physiological stress to fish. Physiological stress was quantified in terms of energy by measuring routine metabolism, food consumption, activity, and growth rates of largemouth bass (Micropterus salmoides) exposed to the organochlorine pesticide dieldrin. Regression analysis was used to estimate models that describe the response of each endpoint as a function of dieldrin concentration and duration of exposure. Metabolic rate, consumption, and growth were influenced by chemical exposure. At short durations of exposure (1-4 days), metabolic rate of exposed fish was depressed compared with controls, but at a longer duration (16 days), metabolic rate increased as a function of concentration. Food consumption and growth rates of fish exposed for 16 days declined as dieldrin concentration increased. The response of each endpoint was consistent with predictions of the general adaptation syndrome. Energetic costs of contaminant-induced changes in metabolism and food consumption can be integrated with a bioenergetics model to demonstrate biological significance of chemical exposure in a natural environment.