Effects of Black Rock Harbor sediments on indices of biotransformation, oxidative stress, and DNA integrity in channel catfish

Abstract

Selected biochemical responses were measured in channel catfish ( Ictalurus punctatus) exposed in the laboratory to sediments obtained from either of two sites in Long Island Sound, CT. These sites were Black Rock Harbor, which is highly contaminated with various aromatic hydrocarbons, and a relatively uncontaminated reference site. Livers and bile were removed from fish on days 2, 7, 14, and 28 following the initiation of sediment exposures and examined for responses associated with (1) xenobiotic biotransformation, (2) oxidative stress, and (3) DNA integrity. Relative to reference sediment exposures in fish, exposures to Black Rock Harbor sediments elicited on at least two of the four sampling points significant ( P < 0.05) increases in: (1) phase I biotransformation enzyme activities (EROD and ECOD) and concentrations of bile metabolites of polycyclic aromatic hydrocarbons (PAHs); (2) antioxidant enzyme activities (SOD and catalase), concentrations of reduced and oxidized glutathione, and malondialdehyde (an index of lipid peroxidation); and (3) the fraction of DNA as single-stranded DNA following alkaline unwinding (an index of strand breaks). The results of this study support hypotheses concerning mechanistic relationships in benthic fish among the metabolism of sediment-associated aromatic hydrocarbons, the generation of free radical intermediates, and mutagenesis. Furthermore, these results support the utility of biochemical responses as tools for assessing contaminant exposures and sublethal effects in aquatic animals.