Changes in methyl mercury concentrations in zooplankton from four experimental reservoirs with differing amounts of carbon in the flooded catchments

Methyl mercury (MeHg) concentrations in zooplankton were compared from four experimental reservoirs at the Experimental Lakes Area in northwestern Ontario, Canada, to test the hypothesis that increases in concentrations of MeHg in zooplankton would be proportional to C availability. The experimental...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2009-11, Vol.66 (11), p.1910-1919
Main Authors: Hall, Britt D, Cherewyk, Katharine A, Paterson, Michael J, Bodaly, R. Drew A
Format: Article
Language:English
Subjects:
Bioaccumulation
Canada
Changes
Correlation analysis
Environmental aspects
Floods
Freshwater
Ions
Mercury
Methylmercury
Organic water pollutants
Plankton
Reservoirs
Water inflow
Zooplankton
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Summary:Methyl mercury (MeHg) concentrations in zooplankton were compared from four experimental reservoirs at the Experimental Lakes Area in northwestern Ontario, Canada, to test the hypothesis that increases in concentrations of MeHg in zooplankton would be proportional to C availability. The experimental reservoirs included three upland reservoirs flooded between 1999 and 2003 that differed in amounts of flooded organic terrestrial C (high, medium, and low C) and an experimental reservoir created over a wetland--peatland complex in 1993. After flooding, MeHg in zooplankton increased from 500 ng*g dry [weight.sup.-1] in all reservoirs. In the first two years of flooding, MeHg in zooplankton was not correlated with amounts of flooded C, but the rates of decline in mean annual concentrations were negatively correlated with the amount of C stored in flooded catchments. Concentrations of MeHg in zooplankton were highly correlated with MeHg concentrations in unfiltered water, with reductions in bioaccumulation associated with increases in dissolved organic C and decreases in pH. Overall, our results suggest that reservoir designs that minimize the amount of flooded terrestrial C should result in shorter periods of elevated MeHg in the food web.
ISSN:0706-652X
1205-7533
DOI:10.1139/F09-123