Mercury and Vernal Pools

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Mercury, toxic to wildlife, is a well-known threat in lakes, ponds and even in forest ecosystems. Yet we know little about mercury's presence or effects on vernal pool systems. VCE is helping to find answers.

VCE Conservation Biologist Steve Faccio is collaborating on a study that will examine landscape influence on vernal pool mercury levels and accumulation in amphibians and invertebrates. Mercury reaches pools via rainfall, leaf litter, and snowmelt, and a vernal pool's relatively high organic matter and low pH can support transformation of mercury to its more toxic and bioavailable form, methylmercury.

Few studies have reported mercury and methylmercury in vernal pools, but levels of mercury in the forest floor have been shown to vary widely with landscape characteristics such as forest type, canopy cover, and land-use over small spatial scales.

For this project, we’re selecting 20 pools identified in the Vermont Vernal Pool Mapping Project and testing their mercury and methylmercury levels and bioavailability. From the data collected during the project’s first year, we’ll select a subset of pools for more intensive biological sampling over time to assess the sources and pathways of mercury and methylmercury. We’ll determine how methylmercury accumulates in breeding amphibians and invertebrates, and assess how amphibians might “export” mercury to the terrestial foodweb – in part by becoming prey to other vertebrates.