Biomarkers of exposure of brown bullheads (Ameiurus nebulosus) to contaminants in the lower Great Lakes, North America

Brown bullheads (Ameiurus nebulosus) from three contaminated sites (Detroit River, Hamilton Harbour. and Black River! and two relatively clean referen ce sites (Old Woman Creek and Bay of Quinte) in the lower Great Lakes were monitored for several biomarkers of exposure to chemical contaminants. Bull heads from the contaminated sites had elevated hepatosomatic indices, incre ased ethoxyresorufin-O-deethylase (EROD) activity, decreased hepatic retino id stores, and a greater incidence of hepatic neoplasms. Fluorescent aromat ic compounds (FACs) in the bile were also elevated in bullheads from the Bl ack River and Hamilton Harbour in comparison to fish from reference sites. A correlation was found between reduction of hepatic retinoid stores and in duction of hepatic EROD activity in bullheads. Principal component analysis of biomarker data demonstrated that biomarker patterns in Detroit River bu llheads were different from those of Black River and Hamilton Harbour bullh eads. Biomarkers in fish are useful monitoring tools for detecting contamin ation of the aquatic environment, but interpretation of results is limited by within-and between-site variability in the responses, some of which may be explained by mobility of the fish. In contaminated areas, bile fluoresce nt aromatic compounds appear to be the best indicator of recent exposure to polynuclear aromatic hydrocarbons, whereas responses to other biochemical biomarkers (e.g., EROD and retinoids) appear to be over a longer time perio d.