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The city of Greenville, SC is a rapidly expanding urban area located on the Reedy River in the upstate of South Carolina. Historical and current point-source pollutants and runoff from impermeable surfaces have resulted in a contaminated river environment, which through previous studies was demonstrated to be reflected in biological effects in fish species in the river. Because it was not known how much smaller tributaries in the urbanized area were contributing to the pollution of the main stem of the Reedy River, we collected fish (bluehead chub (Nocomis leptocephalus), creek chub (Semotilus atromaculatus), bluegill (Lepomis macrochirus), and redbreast sunfish (Lepomis auritus)) from five smaller urban creeks in the Greenville area and measured several biomarkers of exposure in these animals. Enzymatic activities of cytochrome P450-1A (CYP1A) and glutathione S-transferase (GST) were measured, and bile samples were analyzed for fluorescence caused by polynuclear aromatic hydrocarbons (PAHs) and for excreted estrogenic compounds. The results show that some creeks triggered significant biomarker responses in collected fish, while others were relatively clean. In particular, PAHs appear to be prevalent and caused biochemical effects, while estrogenic compounds were not significantly increased in the bile of fish from these urban creeks. A striking observation was the difference in enzyme activities in chub species compared to sunfish species; sunfish had up to five times higher CYP1A activities than chubs, while the chubs had significantly higher GST activity than sunfish. These species differences should be taken into account when they are incorporated in environmental risk assessment and biological effect monitoring programs.

Sunfish and a minnow species were used as indicators of anthropogenic mercury contamination in an east Tennessee stream system receiving multiple point and non-point discharges. The monitoring of bluegill (Lepomis macrochirus) and redbreast sunfish (Lepomis auritus) identified bioavailable mercury near three geographically separate industrial facilities, and was able to detect decreases in contamination with distance away from these facilities. In general, total mercury concentrations in the tissue of sunfish in this study were low in comparison to the most commonly cited human health threshold limits, although concentrations at some sites exceeded 1 μg/g. Caged blacknose dace (Rhinichthys atratulus) were monitored in conjunction with resident fish as an indicator of more discrete sources in selected headwater streams where fish movement was deemed a potential factor affecting mercury body burdens. Mercury concentrations in muscle tissue of caged dace after 12 weeks exposure were generally low (