On Two Sibling Species of the Polychaete Capitella capitata

Abstract

Abstract Assessing the ecological risks of toxic chemicals is generally based on individual-level responses such as survival, reproduction, or growth, even though the aim of ecological risk assessment is most often to prevent adverse effects of chemicals at population, community, and ecosystem levels. In this context, life table response experiments can provide a powerful tool for analyzing the responses of life-history variables to pollutants and to explore demographic consequences of sublethal toxic effects on populations (Levin et al. 1987; Caswell 1989, 1996; Hansen et al. 1999). Specifically, impacts on population dynamics can be estimated by integrating the life-history variables (or vital rates) via an appropriate demographic model to calculate, for example, population growth rate,. Changes in in response to changes in individual life-history traits depend on the life-history type of the study organism, on the severity of the toxicant effect on each life-history trait, and on the sensitivity of to changes in the life-history traits contributing to it (e.g., Levin et al. 1987, 1996; Caswell 1989; Kammenga et al. 1996; Hansen et al. 1999).