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Historical Trends in Tissue Contamination and Genetic Diversity within the Tahoe Basin
Objective:
This project will utilize historic collections of fish and amphibian specimens to ascertain baseline conditions for measuring changes in both tissue contaminant levels and genetic variation over time.
Approach:
- Conduct tissue analysis of historic specimens to determine exposure of amphibian and fish populations to mercury and organic pollutants over time.
- Conduct analyses of changes in genetic structure and diversity utilizing historic and contemporary samples of two amphibians and two fish in the Tahoe Basin.
Why This Research Is Needed:
Studies of temporal changes in genetic diversity have been conducted for diverse species. While these studies provide valuable insight into pre-anthropogenic patterns of genetic variation, it has been difficult to link observed changes to environmental stressors other than direct exploitation and habitat fragmentation. Recent studies of archival tissues in loons and raccoons have provided insight into the onset and persistence of mercury contamination in aquatic ecosystems. Additional studies have used stable isotope analyses of archival tissues to examine changes in trophic structure over time Through an approach that integrates analysis of contaminant exposure and genetic changes we will answer the following questions:
- Do contaminant loadings from sediment cores correlate with changes in amphibian and fish body burden over time?
- Do contaminant loadings from sediment cores correlate with changes in amphibian and fish population structure over time?
- To what extent do modifications to landscape connectivity structure amphibian and fish populations in the Truckee and Carson watersheds?
Expected Outputs/Outcomes:
- Establish the degree of correspondence between patterns of sediment Hg/PBC deposition and body burden in aquatic vertebrates over the last 100 years.
- Understand patterns of genetic variation associated with increased contaminant deposition over the last 100 years.
- Assess historic contamination patterns relative to contemporary threshold exposure guidelines.
Contact: Evon Hekkala - hekkala.evon@epa.gov - Cincinnati, OH