Mercury in Dragonfly Larvae: 2012 Results

Nelson, Sarah; Flanagan, Colleen

Mercury is a globally distributed contaminant that can harm human and wildlife health, and threaten resources the National Park Service (NPS) is charged with protecting. Due in part to emissions and long-range transport from coal‐burning power plants, even remote national park environments receive mercury deposition from the atmosphere. In an effort to increase public awareness regarding the mercury issue, a citizen science project was expanded in 2012 to collect dragonfly larvae for mercury analysis in national parks. Dragonfly larvae (Odonata: anisoptera) can serve as indicators of ecosystem health by characterizing the risk and potential trophic transfer of mercury. These aquatic macroinvertebrates are long-lived before emerging as adult dragonflies, widespread across the U.S., predatory, important prey for fish species, they reflect the mercury sensitivity of a specific watershed, and they are relatively easy to collect. Twelve national parks across the U.S. participated in the citizen science pilot effort: Acadia (ME), Big Cypress (FL), Cape Cod (MA), Channel Islands (CA), Denali (AK), Great Smoky Mountains (NC/TN), Mammoth Cave (KY), Marsh-Billings Rockefeller (VT), North Cascades (WA), Rocky Mountain (CO), Saint Croix (WI/MN), and Saint-Gaudens (NH). This citizen science project engages students, teachers, and visitors in national parks. Moreover, the project supports the “Call to Action,” the NPS Centennial Initiative, by connecting people to parks and advancing the educational mission. Preliminary data indicate that there are significant differences among sites, even within a park, suggesting that these bio-sentinels could be useful in describing fine-scale differences in mercury risk. Across all 12 parks combined, median mercury in dragonfly larvae was 125±77 ppb, dry weight. Mercury concentrations were highest at some sites in Cape Cod NS, Rocky Mountain NP, and Big Cypress NPres. In general, eastern parks had greater dragonfly larval mercury than western parks; a consistent finding given many eastern parks, particularly in the Northeast, are downwind of major coal-fired power plants. In addition to increasing public awareness about mercury issues, this study provides baseline data to better understand the spatial distribution of mercury contamination in national parks. It expands the geographic scope of research previously conducted by scientists and provides data that can be compared across parks. The project will continue in 2013.

Mercury in Dragonfly Larvae: 2012 Results

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