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An Individual-based Model for Extrapolating Standard Toxicity Test Data into Population-level Adverse Outcomes in the Fathead Minnow
Citation:
OLMSTEAD, A. W., M. ETTERSON, R. S. BENNETT, D. HOFF, J. HOFFMAN, R. D. JOHNSON, AND P. K. SCHMIEDER. An Individual-based Model for Extrapolating Standard Toxicity Test Data into Population-level Adverse Outcomes in the Fathead Minnow. Presented at Society of Environmental Toxicology and Chemistry, BOSTON, MA, November 13 - 17, 2011.
Impact/Purpose:
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Description:
While environmental toxicity testing typically focuses on organism-level endpoints such as mortality, growth, and reproduction, risk assessment guidelines specify protection goals at the level of the population and above. One method of linking these different levels of biological organization is the development of models that extrapolate toxicant impacts at the individual level to adverse outcomes at the population level. However, annual population growth projections in highly fecund species such as fathead minnow are subject to extreme uncertainty. We have developed an individual based model for the fathead minnow that integrates adverse effects of stressors on individual growth, reproduction, and survival over a single breeding season using toxicity data inputs from standard toxicity tests such as the early life stage and full life cycle assay. The model uses a daily time step and projects the size-distribution of the population at freeze-up, which is a reliable indicator of the over-winter potential of a fathead minnow population. Specific model outputs are population biomass, census, and size structure. Exposure inputs allow for varying the timing of the exposure in order to compare the effects of various temporal patterns of contamination. Advantages of this type of modeling framework are the ability to introduce greater realism, including density-dependent factors. Data outputs are amenable to long-term, multi-year population modeling if sufficient data on overwinter survival exists.