PH19 Biomonitoring
Exhibit Hall
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(PH223) Contaminant concentrations and biomarker responses of piscivorous and benthivorous fish in the Colorado River Basin.

Hinck, J1, Blazer, V2, Denslow, N3, Gross, T4, Coyle, J5, May, T1, Orazio, C1, Tillitt, D1, 1 USGS-CERC, Columbia, Missouri, USA2 USGS-LSC, Kearneysville, West Virginia, USA3 University of Florida, Gainesville, Florida, USA4 USGS-FCSC, Gainesville, Florida, USA5 USGS-MSC, Fort Collins, Colorado, USA

ABSTRACT- The Biomonitoring of Environmental Status and Trends (BEST) Large River Program measured tissue concentrations of selected contaminants and evaluated biomarker responses in black bass (Micropterus spp.), common carp (Cyprinus carpio), and channel catfish (Ictalurus punctatus) at 14 locations within Colorado River basin in 2003. Major tributaries including the Yampa, Green, Gunnison, San Juan, and Gila Rivers were also sampled. Organic and inorganic contaminants were measured in whole-body composite fish samples, and the H4IIE bioassay determined dioxin-like activity in the samples. Fish health indicators (condition factor, somatic indices), immune system indicators (macrophage aggregate parameters), various molecular biomarkers (EROD, vitellogenin), and reproductive indicators (steroid hormones, gonadal histology) were measured in individual fish. Mean microsomal EROD activity was greatest in carp (>9 pmol/min/mg) from Phoenix, AZ, in catfish (>10 pmol/min/mg) from Vernal, UT and Grand Junction, CO, and in bass (>60 pmol/min/mg) from Vernal, UT. Fish health indicators including macrophage aggregates and oocyte atresia indicated poor health of carp in the Lake Mead area. High health assessment index (HAI) scores in bass, catfish, and carp collected throughout the Colorado River basin were attributed to abnormalities of the liver, kidney, and spleen. Histological examination of the gonads revealed several intersex fish. Data were compared spatially and temporally by examining trends of various persistent contaminants and incorporating existing information from other monitoring efforts. Previous contaminant studies in this basin have a wide range of focus from high concentrations of selenium in irrigation return flows to emerging contaminants downstream of Las Vegas. Other concerns include dropping water levels in the lower Colorado River and the reestablishment of endangered species. The goal of this BEST project is to help characterize fish health and contaminant concerns in the Colorado River basin.

Key words: inorganic contaminants, pesticides, reproductive biomarkers, biological monitoring

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