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Modelling future improvements in the St. Louis River fishery from sediment remediation and aquatic habitat restoration
Citation:
Hoffman, J., L. Burkhard, Greg Peterson, T. Hollenhorst, M. Pearson, A. Cotter, AND J. Launspach. Modelling future improvements in the St. Louis River fishery from sediment remediation and aquatic habitat restoration. St. Louis River Summit, Superior, WI, March 14 - 15, 2017.
Impact/Purpose:
The contamination of fish represents an important loss of ecosystems services globally. US EPA Areas of Concern are Great Lakes coastal communities that were identified as having substantial impairment of beneficial uses associated with aquatic resources owing to a legacy of water and sediment contamination. Among these beneficial use impairments is “Fish Consumption Advisories,” for which legacy contamination of PCBs is commonly a source. Here, we present a spatially-explicit, habitat-based biota-sediment accumulation factor (BSAF) model developed for the St. Louis River Area of Concern. The model can be used to screen and prioritize sites for remediation based on PCBs residues in fish, develop remediation targets, and design monitoring programs to assess progress post-remediation.
Description:
The presence of fish consumption advisories has a negative impact on fishing. In the St. Louis River, an important natural resource management goal is to reduce or eliminate fish consumption advisories by remediating contaminant sediments and improving aquatic habitat. However, we currently lack sufficient understanding to estimate the cumulative effects of these habitat improvements on fish contaminant burdens. To address this gap, our study had two main research objectives: first, to determine the relationship between game fish habitat use and polychlorinated biphenyls (PCBs) concentrations in the lower St. Louis River, and two, to calibrate and validate a habitat-based Biota-Sediment Accumulation Factor (BSAF) model that estimates fish PCBs concentration as a function of both sediment and habitat quality. We sampled two resident fishes, Yellow Perch (Perca flavescens) and Black Crappie (Pomoxis nigromaculatus), and two migratory fishes, Northern Pike (Esox lucius) and Walleye (Sander vitreus) of varying size and from locations spread across the St. Louis River estuary, the largest coastal wetland complex in Lake Superior. We found differences in contaminant concentration that were related to habitat usage, though results varied by species. For migratory fishes, increasing diet from Lake Superior was associated with decreasing PCBs concentration in tissue. For resident fishes, PCBs concentration was highest in the industrial portion of the river. Model calibration demonstrated that existing data sources can be used to accurately estimate fish contaminant burden except in the uppermost reaches of the river. Validation results will be used to improve small-spatial scale estimates. We conclude this approach has strong potential to be used for both initial project screening and to estimate a project’s potential impact to improve the quality of the fishery.