Population survivorship index for fish and amphibians: application to criterion development and risk assessment.

Criterion development currently focuses on physiological responses when determining permitted chemical concentrations in environmental media. Losses of biodiversity attributed to chemical pollution may be related not only to physiological sensitivity but also to inherent population characteristics that are not included in risk assessment or criterion development. In the present study, we proposed a process and a tool for summarizing population- and species-level information that contributes to long-term survivorship. We investigated the influences of life-history strategies of fish and amphibians that contribute to variations in population sensitivity or resiliency. A life-history survivorship index for application in criterion development and risk assessment was developed to help identify which species in a study system possess life-history strategies inherently sensitive to chemical stressors. It includes life-history characteristics of fecundity, number of spawning events, life stages, parental care, attrition rates, time to reproductive maturity, and other factors. Survivorship index values may be used as multipliers to permitting criteria, resulting in toxicological-ecological guidelines that incorporate toxicological information with regional ecological and population characteristics for local or regional application. We intended the procedure to serve as a step toward incorporating population and ecological information into regulatory procedures with the goal of protecting biodiversity from chronic toxic impacts.