BIOCHEMICAL RESPONSES TO SEDIMENT-ASSOCIATED CONTAMINANTS IN BROWN BULLHEAD (AMERIURUS-NEBULOSUS) FROM THE NIAGARA RIVER ECOSYSTEM

Brown bullhead (Ameriurus nebulosus) were collected from three sites i n the Niagara River ecosystem in June and September of 1991, and sedim ent samples from these sites were obtained in July 1991. The sites wer e located in the Buffalo River, the Niagara River adjacent to the Love Canal dump site, and in Black Creek, a Canadian tributary of the Niag ara River which served as a reference site. Sediment samples from thes e sites contained measurable concentrations of various polycyclic arom atic hydrocarbons (PAHs) and chlorinated hydrocarbons (CHs). However, the Buffalo River and Love Canal samples were significantly more conta minated than those from Black Creek. Moreover, Buffalo River samples c ontained greater PAH concentrations than samples from the Love Canal, while the reverse was observed for CHs. Bile and liver of bullhead wer e used for the following analyses: fluorescent aromatic compounds in b ile, a measure of exposure to PAHs, microsomal cytochrome P450 (CYP) a nd P450IA (CYP1A) contents and ethoxyresorufin-O-deethylase (EROD) act ivities, total glutathione (TH-GSH) concentrations, concentrations of 8-oxodeoxyguanosine (8-oxo-dG), and concentrations of hydrophobic DNA adducts (as measured by P-32-postlabelling). Additionally, a laborator y experiment was performed to examine CYP1A-associated responses in bu llhead exposed to the model inducer, beta-naphthoflavone (BNF). Result s from the laboratory induction study were generally consistent with t hose observed in the field study, but the field study results suggeste d gen induction of CYP1A in bullhead from the reference site (Black Cr eek). For both field collections, fish from the Buffalo River displaye d the greatest concentrations of fluorescent compounds in bile and hep atic DNA adducts, whilst fish from the Love Canal site displayed the g reatest microsomal CYPIA concentrations and EROD activities. TH-GSH co ncentrations were significantly greater in Buffalo River fish versus B lack Creek only for the June sampling. No statistically significant di fferences in 8-oxo-dG concentrations in bullhead hepatic DNA were obse rved among the sites at either sampling date. The different patterns i n biochemical responses observed were consistent with sediment chemist ries, and these results suggest that exposure of feral teleosts to dif ferent suites of bioavailable contaminants can be associated with expr ession of a characteristic array of biochemical responses.