Use of sunfish and stoneroller minnows as real-time in situ biomonitors of PCB contamination in freshwater streams

摘要

A long-term polychlorinated biphenyl (PCB) monitoring study was conducted for two moderately impacted freshwater streams in Kentucky. Streamwater, sediment, and fish were analyzed for Aroclors 1248, 1254, and 1260 during 1988-2005. Only 8 of 263 water samples showed detectable PCBs. The low occurrences of PCB detections in streamwater indicated that PCBs were transitory in the water column, rapidly mobilizing into biotic and sediment compartments. One component of this study focused on species-specific patterns of PCB residues in fish, especially the green sunfish (Lepomis cyanellus), longear sunfish (L. megalotis), bluegill (L. macrochirus), and stoneroller minnow (Campostoma anomalum). Stoneroller minnows had higher PCB concentrations and increased frequency of detection when compared to sport fish. Aroclor 1248 was detected 80% of the time in stoneroller minnows from Big Bayou creek, whereas it was only detected in 25-39% of sport fish. In comparison, Aroclors 1254 and 1260 in sport fish were detected 49-69% of the time. These results indicate that higher chlorinated PCB congeners found in Aroclors 1254 and 1260 were not as readily metabolized and excreted by sport fish. No relationships were found between sunfish age and PCB concentrations, which demonstrated that sunfish exposed to low PCB contamination can effectively regulate PCBs, regardless of age. In addition, at low PCB levels (< 0.50 mu Ag/g), green sunfish body burden did not correlate with lipid content. A certain PCB threshold concentration, >= 1.00 mu g/g, must be exceeded before correlations between PCB body burden and lipid content are observed. These results indicate that, at least for species such as the sunfish, the use of the octanol-water partition coefficient (K-OW) under low-level PCB exposure would appear to have little predictive value. Studies by Sanborn et al. (1975) found the green sunfish to be particularly adept at metabolizing organochlorine compounds and PCBs. This field study supports their laboratory findings. Green sunfish may have an enhanced P450 system, or due to low body lipid content, more effectively shunt PCBs into metabolic pathways that detoxify these compounds.