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STABLE GENETIC STRUCTURE OF CENTRAL STONEROLLER POPULATIONS IN A POLLUTED URBAN STREAM
Citation:
Waits, E R., M J. Bagley, J M. Lazorchak, AND F H. McCormick. STABLE GENETIC STRUCTURE OF CENTRAL STONEROLLER POPULATIONS IN A POLLUTED URBAN STREAM. Presented at Society of Environmental Toxicology and Chemistry, Salt Lake City, UT, November 18-22, 2002.
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:
Mill Creek, which runs through Cincinnati, Ohio, is one of the most severely polluted urban streams in the United States. The creek is threatened by streamside landfills and toxic waste sites along the streams banks (including five designated superfund sites), industrial and residential sewage entering the waterway from 164 combined sewer overflows, and contaminated sediments originating from industrial discharge. We hypothesized that fish populations that are severely impacted by highly disturbed systems such as Mill Creek should demonstrate large shifts in allele frequencies (high genetic drift) due to small, unstable population sizes. Ten highly variable microsatellite loci were examined in temporally and geographically separated central stoneroller (Campostoma anomalum) populations residing in contaminated (lower watershed) and relatively uncontaminated (upper watershed) sections of Mill Creek, as well as in an unimpacted stream in a nearby watershed. In contrast to expectations, no significant fluctuations in allele frequencies were encountered between samples collected in 1994/95 and 2001, approximately two generations apart (temporal analysis of molecular variance, p>0.08). Although allele frequencies within sites did not vary with time, allele frequencies did vary significantly between sites. A spatial analysis of molecular variance indicated that 1.4% of allele frequency variance was due to differences among sites (P<0.0001), while just 0.9% was due to differences among sites within Mill Creek (p=0.024). Allele frequency differentiation within Mill Creek appeared related to geographic distance between sites. The implications of these findings for assessment of the condition of fish populations residing in contaminated habitats and for designing effective genetic monitoring programs will be discussed.