Major correlates of mercury in small fish and common loons (Gavia immer) across four large study areas in Canada

• Published in: Environmental pollution (1987) Vol. 210; pp. 361 - 370
• Main Authors: Scheuhammer, A.M., Lord, S.I., Wayland, M., Burgess, N.M., Champoux, L., Elliott, J.E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2016
• Subjects: Acidification; Animals; Birds - blood; Canada; Common loon; Fish; Fishes; Freshwater; Gavia immer; Hydrogen-Ion Concentration; Lakes - chemistry; Marine; Mercury; Mercury - analysis; Muscle, Skeletal - chemistry; Perca flavescens; Perch; Perches; Toxicity; Water Pollutants, Chemical - analysis; PNW, Canada, Manitoba; Acidification; Fish; Common loon; Perch; Toxicity; Mercury
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2016.01.015

We investigated mercury (Hg) concentrations in small fish (mainly yellow perch, Perca flavescens; ∼60% of fish collected) and in blood of common loons (Gavia immer) that prey upon them during the breeding season on lakes in 4 large, widely separated study areas in Canada (>13 lakes per study area; total number of lakes = 93). Although surface sediments from lakes near a base metal smelter in Flin Flon, Manitoba had the highest Hg concentrations, perch and other small fish and blood of common loon chicks sampled from these same lakes had low Hg concentrations similar to those from uncontaminated reference lakes. Multiple regression modeling with AIC analysis indicated that lake pH was by far the most important single factor influencing perch Hg concentrations in lakes across the four study areas (R2 = 0.29). The best model was a three-variable model (pH + alkalinity + sediment Se; Wi = 0.61, R2 = 0.85). A single-variable model (fish Hg) best explained among-lake variability in loon chick blood Hg (Wi = 0.17; R2 = 0.53). From a toxicological risk perspective, all lakes posing a potential Hg health risk for perch and possibly other small pelagic fish species (where mean fish muscle Hg concentrations exceeded 2.4 μg/g dry wt.), and for breeding common loons (where mean fish muscle Hg concentrations exceeded 0.8 μg/g dry wt., and loon chick blood Hg exceeded 1.4 μg/g dry wt.) had pH < 6.7 and were located in eastern Canada. •Yellow perch near two major atmospheric Hg emission sources in Canada did not have elevated Hg concentrations.•(pH + alkalinity + sediment Se) explained more than 80% of among-lake variance in mean yellow perch Hg across all study lakes analyzed together.•only small fish and loons from acidic lakes (pH <6.7) had Hg concentrations high enough to pose potential health risks. In Canada, Hg concentrations in yellow perch exceeded thresholds for toxicity in common loons only in low pH (<6.7) lakes in the eastern part of the country; pH explained much more of the variation in fish Hg than other lake variables.