Effects of industrial metals on wild fish populations along a metal contamination gradient.

The purpose of this study was to examine relationships among water, sediment, and fish tissue metal concentrations as they relate to fish diversity, tissue metal accumulation, and fish morphometric and reproductive condition. Fish were captured in 12 lakes near Sudbury, Ontario, Canada, that ranged in their degree of metal contamination. In general, metal concentrations in water and sediment decreased with increasing distance from industrial operations. However, only Cu and Ni demonstrated this trend in sediments. Although 20 fish species were identified in the 12 lakes, only one species, yellow perch (Perca flavescens), was common to all 12 lakes. Fish diversity was only associated with sediment metals, suggesting that short-term processes are much less important than long-term processes for fish community recovery in metal-contaminated lakes. Multivariate characterization of water metal concentrations resulted in three lake clusters: Group 1 consisted of reference lakes; Group 2 lakes had high alkalinity, conductivity, hardness, pH, waterborne metals (especially Se), and sediment Cu and Ni concentrations; Group 3 lakes had high pH, waterborne and sediment Cu, and sediment Ni, intermediate alkalinity, conductivity, and waterborne metals (except Al and Fe), and low hardness and waterborne Al and Fe. Liver Cd, Cu, Ni, Pb, and Zn, muscle Zn, and intestinal Cd and Zn were highest, and muscle Cu and male gonadosomatic index (GSI) were lowest, in Group 3 fish. Liver, muscle, and intestinal Se concentrations, and Fulton's condition factor (FCF), hepatosomatic index (HSI), and male GSI were highest in Group 2 fish. Group 1 fish had the highest muscle Hg concentrations and female GSI. Muscle Se appeared to have an antagonistic effect on muscle Hg accumulation as a function of distance from smelting operations. Neither Cu nor Ni, both metals of concern in the Sudbury area, was useful for predicting fish condition, probably because of homeostatic regulatory control. Liver Cd accumulation, which was negatively related to FCF (r = -0.16; P < 0.05), exhibited strong, nonlinear inhibition (r2 = 0.99; P < 0.0001) as a function of water hardness. Because Cd was not detected in water samples in this study, we suspect that branchial Ca2+ uptake may play some role in reducing dietary Cd uptake in hard water lakes. Selenium has received relatively little attention in the contaminated systems around Sudbury, yet our results demonstrated that tissue Se was related to all condition metrics studied. Moreover, evidence was provided that suggests that there is a gender-specific interaction between dietary Se and Cu uptake that may contribute to decreased female reproductive condition in wild yellow perch.