Effects of oil sands related aquatic reclamation on yellow perch (Perca flavescens). II. Chemical and biochemical indicators of exposure to oil sands related waters

Abstract

Adult yellow perch (Perca flavescens) were stocked into experimental ponds designed to emulate possible aquatic reclamation alternatives of the oil sands mining industry. After 5 and 11 months, mixed-function oxygenase (MFO) activity, liver conjugation enzymes, bile polycyclic aromatic hydrocarbon (PAH) equivalents, and plasma sex steroids were measured. Liver MFO activity and bile PAH equivalent concentration were closely correlated and showed the highest levels in the experimental ponds but also demonstrated a gradient of exposure among reference locations. Levels of steroid hormones in fall-captured fish did not show major differences among sites. However, during winter, yellow perch from three sites, including the experimental ponds, showed low levels of sex steroids in both males and females. Multivariate regressions showed no relationship between steroid hormone concentrations and gonad size or fecundity. Similarly, steroid hormones did not parallel the gradient of exposure as measured by MFO and bile PAH metabolites. Gonad size and fecundity also were not directly correlated with the gradient of exposure observed in this study. Although MFO activity and bile PAH equivalents were good indicators of exposure to oil sands related waters, they were not predictive of physiological endpoints, suggesting that the latter were influenced primarily by ecological and not by chemical factors.