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GENETIC VARIATION FOR COPPER RESISTANCE IN FATHEAD MINNOW TOXICITY TESTS
Citation:
BrownAugustine, M. C., M J. Bagley, J M. Lazorchak, M E. Smith, AND S. I. Guttman. GENETIC VARIATION FOR COPPER RESISTANCE IN FATHEAD MINNOW TOXICITY TESTS. Presented at Society of Environmental Toxicology and Chemistry, Baltimore, MD, November 11-15, 2001.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Description:
Unexplained variation in the results of aquatic organism toxicity tests is a consistently observed and troubling phenomenon. Possible sources of variation include differences in condition or nutritional status of the population prior to the test, as well as age, density and handling of organisms during the test. One source of variation in test outcomes that is often overlooked is genetic variability within and among stocks of test organisms. The goal of the current study is to assess the relative magnitude of among-stock and within-stock genetic variation for resistance to copper in fathead minnows. Three commercial stocks and one USEPA in-house stock of fathead minnows were reared at the National Exposure Research Laboratory in Cincinnati. Within each stock, mature fish have been paired in spawning chambers with the aim of producing up to 40 full-sib families, divided into approximately 20 paternal half-sib and 20 maternal half-sib progeny groups. Larval fish were exposed to copper at 14-days post hatch, and monitored for mortality in a series of 48-hour time-to-death tests. Preliminary results, which presently have only considered covariances between a subset of the full-sib families, suggest that genetic variation for copper susceptibility within stocks is greater than variation among stocks. As data on half-sib covariances becomes available, we will more thoroughly examine the contributions of additive genetic, nonadditive genetic, and maternal effects to variance in fathead minnow toxicity.