I began the Dragonfly Mercury Project while working on an inquiry-based education program now called Acadia Learning with a group of teachers across Maine and New England, in partnership with the Schoodic Institute.
As teachers and students gathered data on mercury in invertebrates around the region, we noticed that dragonfly larvae seemed to be fairly ubiquitous — we found them in streams, ponds and wetlands in a variety of settings — and there were some patterns in the mercury concentrations that suggested dragonfly larvae could be good indicators of what we thought were landscape characteristics that tend to be more conducive to mercury bioaccumulation.
The project expanded to 11 national parks with pilot funding from the University of Maine in 2012, then grew to include 25 parks with National Park Service funding in 2013. With UMaine, collaborators at the U.S. Geological Survey (now the lead organization), National Park Service, Dartmouth College and University of Wisconsin-La Crosse joined in writing a proposal that led to sampling in over 50 parks from 2014–2015. Because of the interest in the project, the National Park Service and many individual parks have contributed funds to continue the project in 2016, the NPS centennial year. Approximately 60 parks are slated to contribute samples throughout the 2016 centennial.
Hamish Greig and Amanda Klemmer, faculty in the School of Biology and Ecology and EES programs, are working to expand the project’s scope to include implications for aquatic food webs.
There are several advantages, both scientifically and logistically, to dragonfly larvae bio-sentinels. First, they spend most of their life cycle (up to several years) in freshwater aquatic ecosystems, where methylation of mercury to its toxic form is thought to largely occur. Second, they are predators, and also are prey for many aquatic organisms, occupying a key position in many aquatic food webs. Third, they are ubiquitous; we find larvae in sites from Alaska to Maine to California to Florida, and even desert oases in the arid Southwest.
They also provide a bio-sentinel for bodies of water that are fishless, like small wetlands, ponds or some streams. They exhibit site fidelity, meaning a dragonfly larva represents the site conditions of the water in which it was captured; it hasn’t migrated from elsewhere or spent any of its life in a different ecosystem.
The typical concentrations of mercury in larvae that we have analyzed is in a range that’s straightforward for a relatively inexpensive type of laboratory analysis, which allows us to analyze samples individually and capture the range of variability within and across sites. The larvae are relatively large, providing plenty of material for laboratory analysis, and they are easy to identify with minimal training, which allows for their sampling by citizen scientists. Lastly, they are far easier to collect than fish, and can potentially serve as a surrogate for fish mercury concentrations.
Citizen science makes this project possible. Over 2,000 citizen scientists, from schoolchildren to Girl Scouts to Youth Conservation Corps to visiting teachers to park visitors have participated. Together, these volunteer scientists have contributed hours that add up to over two full-time staff for a year’s worth of time, and have covered the broad geography of the project. We wouldn’t be able to cover the same ground and get all of the sites sampled if only project scientists were in the field.
Furthermore, the inclusion of lay scientists has generated numerous educational materials about mercury, dragonflies and national parks. Their involvement has spread awareness of this project, and participating classrooms also are using the data and presenting the research.
We are concerned about mercury in parks and other seemingly “pristine” locations across the U.S. and globe because mercury is toxic and thereby challenges the National Park Service mandate to maintain resources “unimpaired” for future generations.
Additionally, like other air pollutants, mercury doesn’t respect park boundaries. Air pollution is a challenging issue for that reason: atmospheric air masses move and deposit everywhere, not just where pollution was created. U.S. Geological Survey researchers have found nearly half of lakes and a quarter of streams had fish that exceeded the U.S. Environmental Protection Agency’s advisory level of 0.3 ppm. In parks, we are concerned about mercury not only for the human health implications, but also for the sake of wildlife that depend on aquatic food webs.
The Dragonfly Mercury Project provides the ideal vehicle for connecting people with parks and using parks as outdoor laboratories. The hands-on, minds-on approach can allow anyone interested to participate in a real scientific research study, and learn how to be a scientist for a day.
Sarah Nelson is the director of the ecology and environmental sciences program and an associate research professor in the School of Forest Resources