SS3.12 Large Scale Ecosystem Manipulations
Date: Thursday, June 13, 2002
Time: 4:45:00 PM
Location: Carson C
 
Peech, K, A, University of Manitoba, Winnipeg, Canada, peechk@dfo-mpo.gc.ca
PatersonMJ, Freshwater Institute, Winnipeg, Canada, patersonm@dfo-mpo.gc.ca
Bodaly, R, A, Freshwater Institute, Winnipeg, Canada, bodalyr@dfo-mppo.gc.ca
Hall, B, D, University of Alberta, Edmonton, Canada, bhall@gpu.srv.ualberta.ca
 
METHYLMERCURY IN THE FOOD WEBS OF NEW RESERVOIRS: THE FLOODED UPLANDS DYNAMICS EXPERIMENT
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The creation of reservoirs typically stimulates decomposition of flooded vegetation and mercury methylation, which results in elevated concentrations of methyl mercury (MeHg) in fish. As part of the FLooded Uplands Dynamics EXperiment (FLUDEX) at the Experimental Lakes Area we examined the hypothesis that concentrations of MeHg in fish and other biota are determined by amounts of decomposable carbon in flooded watersheds. We measured concentrations of MeHg in water, zooplankton, emerging insects, and fish from 4 experimental reservoirs that flooded watersheds with different amounts of stored C. We also examined MeHg in biota from several natural lakes for a total data set of 24 lake-years. Flooding invariably resulted in large increases of MeHg in water and the magnitude of increases approximately followed patterns of C storage. MeHg concentrations in biota, however, were not strongly correlated with C storage. This was because higher concentrations of DOC in reservoirs with greater C storage apparently inhibited the transfer of MeHg from water to biota. Hg accumulation by fish was strongly correlated with MeHg concentrations in invertebrates, but only weakly correlated with MeHg in unfiltered water.