Validating Landscape Models for Mercury in Northeast Lakes using Dragonfly Nymphs as Mercury Bio-sentinels
Collaborator
Bill Zoellick, Schoodick Institute
Abstract
Mercury (Hg) is a toxic pollutant that is widespread in northeastern US ecosystems. Resource managers’ efforts to develop fish consumption advisories for humans and to focus conservation efforts for fish-eating wildlife are hampered by significant variability in fish Hg concentrations from site to site - often in neighboring lakes. Watershed characteristics that vary across the Northeast such as forest type and wetlands are important predictors of methylation. Although data syntheses leading to hotspot maps (e.g., Evers et al. 2007) and sensitivity modeling have been conducted (Krabbenhoft et al. 2011), we still lack studies that use sentinel biota and have statistically rigorous sampling designs across the broad region. Fish Hg concentrations are most often used as biological indicators of Hg sensitivity in lakes; however, fish may move between waterbodies and interpretation can be confounded by size, species, diet, gender, and age. This project sampled lake water and a biosentinel, dragonfly larvae, in a statistical sample of 74 lakes that are part of US EPA long-term monitoring across the region to (1) test models for prediction of Hg and MeHg in water, and (2) determine the efficacy of this bio-sentinel in predicting sensitivity to Hg across the region. In the Upper Midwest, MeHg in dragonfly larvae was significantly, positively correlated with THg in perch (Knights et al. 2005) and researchers concluded that dragonfly larvae were promising bio-sentinels in that region (Haro et al. 2013). We hypothesized that dragonfly larvae are good indicators of Hg spatial patterns because they are widespread in fresh waters across this region, long-lived (1-5 years or more), exhibit site fidelity, are carnivorous, contain almost all of their Hg as MeHg, and have relatively high Hg concentrations. The project leveraged ongoing research at a statistical sample of 74 lakes across New England states and New York, sampled annually by cooperators in the US Environmental Protection Agency (EPA) Long-Term Monitoring (LTM) Network.
Funding support for this project was provided by the Northeastern States Research Cooperative (NSRC), a partnership of Northern Forest states (New Hampshire, Vermont, Maine, and New York), in coordination with the USDA Forest Service, http://www.nsrcforest.org
Rights Statement
