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IP07 Population-Level Ecological Risk Assessment
(IP055) Modeling Impacts on Populations: Fathead Minnow (Pimephales promelas) Exposure to the Endocrine Disruptor 17-B-Trenbolone as a Case Study.
Miller, D.1, Ankley, G.2, 1 U. S. E. P. A., National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Grosse Ile, Michigan, U.S.A.2 U. S. E. P. A., National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, Minnesota, U.S.A.
ABSTRACT- Evaluation of population-level impacts is critical to ecological risk assessments. In this study, a predictive model was developed to translate changes in fecundity of the fathead minnow (Pimephales promelas) in a short term laboratory toxicity test to alterations in population growth rate. The model uniquely combines a Leslie population projection matrix and the logistic equation. Application of the model requires only a life table for the organism of interest, a measure of carrying capacity for the given population, and estimation of the effect of a stressor on vital rates. The model was applied to investigate population dynamics for fathead minnow exposed to the androgen receptor agonist 17-B-trenbolone. Organismal-level responses for fathead minnows exposed to varying levels of 17-B-trenbolone were used to determine projected alterations in a population existing in a small body of water containing varying concentrations of the androgen. Fathead minnow populations occurring at carrying capacity and subsequently exposed to 0.027 ug/L of 17-B-trenbolone exhibited a 51% projected decrease in average population size after 2 years of exposure. Populations at carrying capacity exposed to concentrations of 17-B-trenbolone ≥ 0.266 ug/L exhibited a 93% projected decrease in average population size after 2 years of exposure. Overall, fathead minnow populations exposed to continued concentrations of B-trenbolone equal to or greater than 0.027 ug/L were projected to have average equilibrium population sizes of zero.
Key words: fathead minnow, population projection, endocrine disruptor, logistic equation
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