Biomarkers can be used as tools to help determine ecological exposure in watershed assessments. In the present study, metallothionein and fixed wavelength bile fluorescence for two-, four-, and five-ring hydrocarbons were used as biomarkers of exposure in largemouth bass (Micropterus salmoides) in the Reedy River watershed located in South Carolina, USA. Fish were sampled from three impoundments and a reference site over three seasons in the same year. Biomarker endpoints were compared to chemical concentrations at each site during each season. Results indicated that despite elevated concentrations of hydrocarbons being present in sediments, the hydrocarbons did not appear to be bioavailable based on bile fluorescence analysis. Bile fluorescence analysis also indicated that the hydrocarbons detected in this watershed were likely of petrogenic origin. Significantly elevated sediment concentrations of Cd, Cr, Cu, Pb, Ni, Ag, Zn, and metallothionein were found in one impoundment, Lake Conestee, compared with the reference site, indicating both the presence and bioavailability of these metals. Seasonal variability of bile fluorescence was limited; however, metallothionein showed elevated concentrations in the spring and summer compared with fall.
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