Ratio of Mercury Concentration to PCB Concentration Varies with Sex of White Sucker (Catostomus commersonii)

Charles Madenjian,John Dewild,Jacob Ogorek,Lynn Ogilvie,Peter Mcintyre,Martin Stapanian,William Edwards,Andrew Stevens,David Krabbenhoft

doi:10.3390/environments5090094

Abstract

The whole-fish total mercury (Hg) concentrations were determined in 25 mature female and 26 mature male white suckers (Catostomus commersonii) caught during their spawning run in the Kewaunee River, a tributary to Lake Michigan. The age of each fish was estimated using thin-sectioned otoliths, and total length (TL) and weight were determined for each fish. When adjusted for the effect of age, males were found to be 7% higher in Hg concentration than females. Nearly all (about 98%) of the Hg found in the white suckers was determined to be methylmercury. In an earlier study on the same 51 white suckers from the Kewaunee River spawning run, males were found to be 18% higher than females in polychlorinated biphenyl (PCB) concentration. We determined that the ratio of Hg concentration to PCB concentration in females was significantly higher than that in males. Thus, sex significantly interacted with contaminant type (Hg or PCBs) in determining contaminant concentrations. The most plausible explanation for this interaction was that males eliminated Hg at a faster rate than females, most likely due to the boosting of the Hg-elimination rate by certain androgens such as testosterone and 11-ketotestosterone. Hg concentrations in the white suckers were well below federal guidelines for fish consumption.

Highlights

Mercury is a naturally occurring element on Earth, human activity has led to widespread mercury contamination of terrestrial and aquatic ecosystems [1,2]
Hg concentration was significantly different from the effect of sex on the polychlorinated biphenyl (PCB) concentration
The whole-fish Hg concentration of mature white suckers caught during the spring spawning run in the Kewaunee River, a tributary to Lake Michigan, was 7% higher in males than in females

Summary

Introduction

Mercury is a naturally occurring element on Earth, human activity has led to widespread mercury contamination of terrestrial and aquatic ecosystems [1,2]. The primary route of exposure of mercury to humans is via the consumption of fish [1,2,3,4]. Among the most serious threats to human health from mercury contamination is the impairment of normal brain development in the fetus [5,6,7,8,9,10,11]. Determinations of mercury concentrations in fish fulfill essential roles both in developing fish consumption advisories and in assessing risk to humans and wildlife consuming contaminated fish [7,13,14,15,16,17]. The predominant form of mercury in fish is methylmercury [18]

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