Seasonal and regional variations of metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. I. Factors influencing tissue metal concentrations


This study examined relationships among water, sediment, diet and fish tissue metal (Cd, Cu, Ni, Se and Zn) concentrations in yellow perch from metal gradients in two regions (Sudbury (S), Ontario and Rouyn-Noranda (RN), QuÈbec Canada) in two seasons (spring and summer). The objectives of this study were (i) to examine the influences of aqueous and dietary metal contamination on yellow perch liver and kidney metal accumulation; (ii) to compare the seasonal and regional variations in gut content and tissue metal concentrations along the two gradients studied; and (iii) to investigate the potential of metals for tissue accumulation under conditions of life-long chronic exposure. Contaminated RN lakes were characterized by elevated concentrations of Cd, Cu and Zn in water and sediment, while contaminated Sudbury lakes were characterized by elevated concentrations of Cd, Cu and Ni in water, and Cu and Ni in sediment. Dietary metal contamination largely reflected water and sediment contamination for Cd and Cu and to a lesser extent for Ni and Zn, but not for Se. Liver and kidney concentrations of Cd and Cu, and to a lesser extent Ni, Se and Zn, also correlated with dietary contamination, indicating that both aqueous and dietary sources are significant contributors for these metals. Dietary metal concentrations often decreased, but never increased, with size, suggesting that metal exposure through diet generally decreases in larger yellow perch. Although Cd accumulated in the tissues of older fish from some lakes in the RN region, overall, metals did not accumulate with age in liver or kidney of fish from either region. Seasonal variations in tissue metal concentrations were inconsistent between regions, and sometimes also between tissues. Our data suggests that S fish, having been historically exposed to high concentrations of Cu and Ni, may have evolved better capacities for the regulation of tissue concentrations of these metals compared to RN fish. Finally, of all the metals examined, Zn appeared to be the most regulated, and Cd the least. This data clearly highlights the importance of repeated sampling for assessing effects of metal contaminants in wild fish, and further suggests that yellow perch from Sudbury may have adapted to metal exposure.