PM21 New Advances in Estimating Effects of Toxicants on Populations
Exhibit Hall
8:00 AM - Monday
(PM305) An approach for assessing the ecological significance of toxicant-induced effects for risk assessments.
Salice, C1, 1 US Army Center for Health Promotion and Preventive Medicine, APG, MD, USA
ABSTRACT- Evaluating the significance of toxicant-induced effects is an important challenge for ecotoxicology and ecological risk assessment. There are a number of methods for assigning the significance of an effect that range from a qualitative sense for what constitutes a deleterious effect to a blanket effect level whereby an x% decrease or increase in a parameter represents a meaningful effect. A more quantitative approach to assessing ecological significance would likely facilitate ecological risk assessment and management efforts. An approach is outlined and demonstrated for assessing the ecological significance of toxicant-induced alterations in survival, reproduction and to a lesser degree, growth. The method entails using population models to place effects in the context of a specific receptor life history. In this way, one can determine if, in the context of the entire life history, an effect is significant by how much a population-level parameter (population growth rate, population size) is altered. The method can accommodate variability and uncertainty by incorporating a probabilistic approach. Stage or age-based population models are used to demonstrate how differences in life history relate to toxicant-induced effects in population-level parameters. In one simulation, a 20% reduction in fecundity for fence lizards resulted in a 10% decrease in population growth rate while a similar effect in painted turtles resulted in only a 2% decrease in population growth rate. In both cases, a 20% reduction in fecundity did not cause population growth rate to go below one, which would indicate the population would decline over time. Although these were simple models, the insight provided may be useful and more descriptive models can be used if sufficient data is available.
Key words: ecological signficance, population model, risk assessment, toxicity