Modelling population exposure-response functions for use in environmental risk assessment

Abstract

Effective environmental management requires accurate prediction of the probable individual, population, and ecosystem responses associated with environmental hazards. While much is known about the short-term physiological impacts of toxicants at the individual level, little is known about the long-term responses of populations. This occurs, in part, because of the costs and difficulties associated with completing long-term studies. In the absence of such field data it is argued that modelling both bridges the existing information gap and provides a credible means of predicting long-term population responses. An individuals-based Atlantic salmon (Salmo salar) population dynamics model, adjusted to include laboratory-derived acute toxicity data, is used to measure recovery time in a population subjected to concentrations and durations of copper exposure characteristic of an accidental release of mine tailings. Selected recovery criteria are proposed and discussed in terms of their suitability for use in environmental risk assessment. The resulting model data are used to estimate population exposure-response functions and, for purposes of environmental risk assessment, to describe the cumulative probability distribution ofin-situ environmental damage. The output of the model suggests a recovery time of 15 to 20 years and significant increases in the variability of post-perturbation population levels.