ABSTRACT
This chapter provides an interpretative framework for evaluating the relative importance of direct and indirect pathways or mechanisms on the expression of pollutant responses in fish. In addition, the role of important ecological factors such as competition, food, and habitat availability in helping to understand the biological significance of contaminant-related stressors on aquatic organisms is also evaluated using examples from field data. A helpful approach for achieving a better understanding of the relative importance of direct and indirect mechanisms in evaluating the responses of fish populations to multiple environmental stressors is to measure a selected suite of stress indicators representing several major categories of response indicators. The consideration of both direct and indirect mechanisms of pollutant stress along with a basic understanding of how principal ecological factors can modify organism response to contaminants should provide an interpretative framework for evaluating the effects of chronic stressors on aquatic organisms.
