Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

Environmental Pollution
By: , and 

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Abstract

Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes
Series title Environmental Pollution
DOI 10.1016/j.envpol.2016.01.049
Volume 212
Year Published 2016
Language English
Publisher Applied Science Publishers
Publisher location Essex, England
Contributing office(s) Forest and Rangeland Ecosystem Science Center, Contaminant Biology Program
Description 11 p.
First page 279
Last page 289
Online Only (Y/N) N
Additional Online Files (Y/N) N