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Tracing contaminants through the St. Louis River food web
Citation:
Hoffman, J., A. Cotter, G. Peterson, T. Hollenhorst, G. Hanson, J. Pinkerton, A. Bracey, M. Etterson, C. Roesler, N. Johnson, V. Blazer, P. Mazik, S. Janssen, J. DeWild, J. Ogorek, M. Tate, AND D. Krabbenhoft. Tracing contaminants through the St. Louis River food web. St. Louis River Summit, Superior, WI, March 05 - 06, 2019.
Impact/Purpose:
Under the Remediation to Restoration to Revitalization framework, we assess the effect of combined sediment quality and aquatic habitat improvement on ecosystem services. A common ecosystem service of substantial value to the community is high-quality, edible gamefish and the associated fisheries. In this presentation, we demonstrate a tracer-based approach to improve the quality of contaminant monitoring in fish and wildlife. This approach could be used to track progress in reducing contaminant burden in fish and wildlife post-remediation.
Description:
Long-standing contaminants of concern for the St. Louis River Areas of Concern (AOC) include polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs, or dioxins), polychlorinated dibenzofurans (PCDFs, or furans), polyaromatic hydrocarbons (PAHs), and heavy metals, all of which are present at multiple locations in the AOC. Concentrations are sufficiently high to cause fish consumption advisories for PCBs and mercury, and possibly present a risk to piscivorous fish and wildlife. However, within- and among-species variability in contaminant concentrations in fish tissue is substantial, which presents a substantial challenge for assessing current risk and future progress. We have applied carbon and nitrogen stable isotope analysis in a variety of contaminant studies in the AOC, and used this approach to reveal how this variability may relate to trophic position, habitat use, diet habit, and seasonal movements in invertebrates, fish, and wildlife. We conclude that demonstrating progress in reducing contaminant concentrations in fish and wildlife that use the AOC as habitat will require a tracer-based approach to account for variability associated with habitat use and seasonal movements.