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(421) Foraging Behavior in Contaminated Environments: Implications for Population-Level Dose. Purucker, Tom1, Hallam, Tom1, Stewart, Robert1, Welsh, Chris1, 1 ABSTRACT- A dynamic state variable model, which simulates the behavior of individuals under different degrees of optimality, is used to simulate foraging behavior in an environment with spatially heterogeneous contaminant concentrations. In the process of foraging, individuals accumulate contaminants via direct ingestion of soil and the associated contaminated vegetation. Iteration of these models allows one to construct a distribution of the received doses for a given population. In this implementation, the quality of a patch is reflected in the probability that a forager can find food. An optimal forager is assumed to be adept at finding patches with the highest probability of finding food. Therefore, the patch dependent probability controls where foragers feed. As individuals feed on a particular patch, this probability of finding a food item within the patch diminishes and other patches may then become more desirable, resulting in switching behavior of the individual as appropriate. Results from simulations in areas with high correlations between contamination and desirable patches are compared to areas with low (or negative) correlations to demonstrate the impact on the dose distribution of a population. Results of high versus low spatial variability of contaminat concentrations are also examined. The model results demonstrate that the degree of correlation between the spatial distribution of a contaminant and desirable foraging patches can contribute significantly to the population dose received. This source of uncertainty is not accounted for in current ecological risk practice where a statistical summary of the contaminant data is used to derive the received dose of foragers. Key words: exposure, foraging, spatial, risk |
