The Dragonfly Mercury Project: 2013 Results

Nelson, Sarah; Flanagan Pritz, Colleen

Mercury concentrations (dry weight, ppb) were analyzed in 775+ dragonfly larvae from 22 NPS units, plus 1 state park. Samples also identified to family. Water samples also analyzed for total mercury (THg) and mercury-relevant chemistry (pH, DOC, SO4). 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, citizen scientists, working with park staff, are collecting and submitting dragonfly larvae samples for Hg analysis. The study started in a handful of national parks in 2010–2011, and included 12 parks in the 2012 pilot year. The data herein reports on a NPS-wide expansion to 22 parks during 2013: Acadia NP (ME), Big Cypress NPres (FL), Cape Cod NS (MA), Cuyahoga Valley NP (OH), Denali NP & Pres (AK), Great Smoky Mountains NP (NC/TN), Golden Gate NRA (CA), Jean Lafitte NHP & Pres (LA), Kenilworth Aquatic Gardens (DC), Knife River Indian Villages NHS (ND), Mammoth Cave NP (KY), Monocacy NB (MD), Marsh-Billings-Rockefeller NHP (VT), Niobrara NSR (NE), North Cascades NP (WA), Ozark NSR (MO), Pictured Rocks NL (MI), Rocky Mountain NP (CO), Saint Croix NSR (WI/MN), Saint-Gaudens (NH), Voyageurs NP (MN), Yellowstone NP (ID/MT/WY). One state park, Stone Mountain State Park (GA), also participated. 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. Over 775 dragonfly larvae samples from 60 distinct sites were analyzed in 2013. Total mercury (THg) concentrations ranged from below the detection limit to 844 parts per billion (ppb), on a dry weight (dw) basis. The median ± standard deviation (SD) THg concentration was 125 ± 77 ppb, dw. Data indicate that sites with the greatest dragonfly larvae total mercury (THg) concentrations were located in New England, as well as western sites that could be influenced by regional or local influences. 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. Forty-six NPS units participated in the 2014 sampling effort, and sampling will continue in numerous parks in 2015.

The Dragonfly Mercury Project: 2013 Results

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