For more information about National Park Service air resources, please visit http://www.nature.nps.gov/air/.


Citizen Scientists Study Mercury in Dragonfly Larvae

After up to 5 years in the water, a dragonfly larvae emerges as an adult, leaving behind the “exuviae�, Acadia NP, Maine.  Photo courtesy of the SERC institute. Volunteers at Cape Cod NS, Massachusetts, collect dragonfly larvae at Ryder Pond. Photo by Ken Shea. Gomphid, the most common dragonfly larvae family collected. Photo courtesy of the University of Maine. A students searches for dragonfly larvae during the Bioblitz at Rocky Mountain NP, Colorado. Photo courtesy of the National Geographic Society.
Students, teachers, park visitors, "BioBlitz'ers," and other citizen scientists collect dragonfly larvae samples in national parks for mercury analysis.

Dragonfly larvae are currently being sampled for mercury levels in national parks. Mercury is a toxic pollutant that can harm human and wildlife health, threatening the natural resources the NPS is charged with protecting.The main source of human-caused mercury in remote national park environments is atmospheric deposition from coal-burning power plants.

The larval stage of the dragonfly lives in the water, and individuals are collected from river or lake bottoms with nets. Dragonflies spend most of their life in the larval form and eventually morph to the fast-flying aerial predator in the adult phase.

This project engages citizen scientists such as students and visitors in national parks to collect dragonfly larvae from distinct sampling sites. The samples are then sent to the University of Maine or Dartmouth College laboratories for mercury analyses. The study connects people to parks and provides baseline data to better understand the spatial distribution of mercury contamination in national parks.

National parks from Alaska to Florida and Maine to Colorado participated in the 2012 pilot study. Data are available and results allow comparisons between parks. Sampling will continue in 2013, and ultimately, data will shed light on ecosystem health by characterizing the risk and potential transfer of mercury around food webs.


Map of national park units participating in the dragonfly study in 2012.
Participating national park units, 2013. Map background shows measured and interpolated mercury deposition, data courtesy of NADP/Mercury Deposition Network.

Why Dragonfly Larvae?

Diagram illustrating that levels of mercury increase in concentration along the food chain.
The toxic form of mercury, methylmercury, increases in concentration in the food chain.

Dragonfly larvae build-up higher levels of mercury than other types of water-dwelling insects for two reasons. First, they are predators that eat a lot of smaller insects and are relatively high in the food chain. Second, they live a long time in the larval stage (up to 5 years!), eating and accumulating mercury as they grow and develop.

Levels of mercury in dragonfly larvae are important to understand because dragonfly larvae are also a food source for many types of fish. Fish are higher on the food chain and accumulate even more mercury. Fish are then eaten by birds and mammals, including humans, posing an even greater risk to health. Fish are more difficult to sample, particularly because they can move faster and are much bigger than dragonfly larvae.

For more information, or if interested in participating, contact us or phone Colleen Flanagan, Ecologist, at 303-969-2806.



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Acknowledgements

    This project began as part of Acadia Learning, a collaboration with the Schoodic Institute at Acadia National Park, the University of Maine, and Maine Sea Grant. The project was funded in large part by the NOAA B–WET (Bay Watershed Education and Training) Program and the University of Maine through Faculty Research Funds and High End Instrumentation Research. Key personnel who are contributing include:

  • Dr. Sarah Nelson, University of Maine, George J. Mitchell Center for Environmental and Watershed Research
  • Celia Chen and Hannah Roebuck, Dartmouth College
  • Clive Devoy and Marianne Lagerklint, University of Maine Sawyer Environmental Chemistry Research Lab
  • Roger Haro and Jim Wiener, University of Wisconsin–Lacrosse
  • National Park Service staff and citizen scientists

Last Updated: March 04, 2014