Mercury concentration in black flies Simulium spp. (Diptera, Simuliidae) from soft-water streams in Ontario, Canada.
Total Hg in Simulium spp. (Diptera, Simuliidae) was measured in 17 soft-water streams in the District of Muskoka and Haliburton County (Ontario, Canada) during 2003 and 2004. Black flies contained 0.07-0.64 microg/g total Hg (dry weight). The methylmercury concentration was measured in 6 samples of the 17, and ranged from 58% to 93% of total Hg. The concentration of total Hg is much higher than has been found in other filter feeding insects, and represents a significant potential source of Hg to fish. Mercury concentrations in Simulium spp. at different sites were strongly positively correlated with dissolved organic carbon, and the proportion of land within each catchment that was wetland. There was also a strong negative correlation with pH. By examining Hg concentration in filter feeding insects we have found a significant entry point for Hg and MeHg into the food web.
Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada.
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Harding
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Gowland
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Dillon
D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D020387:Food Chain; D005618:Fresh Water; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D009864:Ontario; D012843:Simuliidae / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury