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. Résumé : Les auteurs présentent des données empiriques sous-tendant un cadre conceptuel selon lequel les contaminants chimiques constituent une source de stress physiologique pour les poissons. Pour quantifier la valeur énergétique du stress physiologique engendré par ces substances, ils ont mesuré le métabolisme normal, la consommation de nourriture, l'activité et les taux de croissance chez des achigans à grande bouche (Micropterus salmoides) exposés à la dieldrine, un insecticide organochloré. Au moyen d'analyses de régression, ils ont estimé des modèles décrivant les fluctuations de chaque paramètre en fonction de la concentration de dieldrine et de la durée d'exposition. La vitesse de métabolisme, la consommation de nourriture et la croissance variaient en fonction de la durée d'exposition. Le métabolisme des poissons exposés durant de courtes périodes (1-4 jours) était plus lent que celui des poissons témoins. En revanche, en cas d'exposition prolongée (16 jours), le métabolisme s'accélérait en fonction de la concentration de dieldrine, mais la consommation de nourriture et les taux de croissance diminuaient. L'évolution de chaque paramètre était compatible avec les caractéristiques d'un syndrome général d'adaptation. Le coût énergétique des changements intéressant le métabolisme et la consommation de nourriture induits par l'exposition au contaminant peuvent être intégrés dans un modèle bioénergétique pour démontrer le retentissement biologique de l'exposition à un contaminant chimique en milieu naturel.

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.

No abstract

No abstract