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Evaluating life history, habitat and contaminant risk factors to fish health in an urban river
Citation:
Hoffman, J., P. Mazik, AND V. Blazer. Evaluating life history, habitat and contaminant risk factors to fish health in an urban river. 2018 Ocean Sciences Meeting, Portland, OR, February 11 - 16, 2018.
Impact/Purpose:
Areas of Concern (AOCs) are areas within the Great Lakes that have lost beneficial uses associated with coastal ecosystems owing to legacy contamination and land uses. The presence of fish tumors and deformities are among the fourteen beneficial use impairments identified. Here, we present the methods and results of a new assessment approach for determining the status of this impairment, using the St. Louis River AOC to demonstrate the approach. We found that tumor prevalence was low, and was primarily associated with biological factors and not diet-related factors. Application of diet-based tracers allowed us to control for individual differences in diet-based exposure; nevertheless, it was impossible to completely assess the role of contaminants in tumor development.
Description:
The St. Louis River watershed has been profoundly changed by over 150 years of human development that resulted in widespread pollution and habitat degradation, especially around the St. Louis River “estuary” near Lake Superior. In 1987, the river was designated as an Area of Concern (AOC) primarily due to historical degradation, which included inappropriate discharge of untreated wastewater, debris from industrial and municipal facilities, and poor community land-use practices. Introduction of aquatic invasive species (especially benthic species) is both a historical and contemporary problem. When the AOC was designated, the widespread presence of fish tumors and deformities owing to exposure to contaminated sediments were identified as an impairment; however, no studies to document the types, severity or prevalence of fish tumors were conducted until this assessment was initiated in 2011. Our objective was to assess the prevalence of white sucker (Catostomus commersonii) fish tumors and deformities, as well as associated biological and habitat quality-related risk factors for liver and skin neoplasms. We found that biological factors age and sex were significant factors. We also found that that tumor prevalence was not associated with migratory life history as indicated by diet markers, but was associated with capture location. Higher neoplasm rates together with the higher PCBs concentrations in tissues of white sucker captured in two areas of the river are notable because these areas are subject to many stressors, including poor water quality and sediment quality, as well as aquatic invasive species. Our results highlight the challenge to untangle pathways between ontogenetic development, life history, contaminant exposure, stressors, and the presence of other initiators or promoters.