How an Insect Became a National Park Service Superhero

Through the power of partnerships, the Dragonfly Mercury Project elevated the importance of a commonly found insect. It also showed that citizen science can be a potent research tool.

By Colleen Flanagan Pritz, Katherine Ko, Sarah J. Nelson, and Collin A. Eagles-Smith

Four teenage citizen scientists gather around a man in a National Park Service uniform to see what one of them have caught in a green net. They stand on a sandy shore next to water. Green trees and shrubs are behind them.
Dragonfly Mercury Project citizen scientists at Saguaro National Park.

Image credit: NPS / Colleen Flanagan Pritz

Mercury is a globally pervasive pollutant that can end up in otherwise pristine places like national parks. It occurs naturally in the environment, but humans are reponsible for much of the mercury cycling through the environment.

We discharge mercury through activities like burning coal to produce energy, mining gold, and incinerating waste. Naturally occurring bacteria can convert mercury to methylmercury, a more toxic form, which bioaccumulates in fish and other animals. Methylmercury is the leading cause of fish consumption advisories in the United States. In people, mercury can adversely affect speech, hearing, vision, and movement.

Combating this potent neurotoxicant requires knowledge about how much of it is in the environment and where it occurs. A decade ago, the National Park Service and a few of its partners launched the Dragonfly Mercury Project to measure mercury in dragonfly larvae. With this information, scientists can extrapolate the occurrence and prevalence of mercury to determine potential risk for other living organisms and their ecosystems. Through partnerships, volunteers, and networking, the Dragonfly Mercury Project has become the largest, longest running, biological mercury monitoring program in the United States.

Closeup of a live dragonfly larva on a person's palm
Dragonfly larva

Image credit: U.S. Geological Survey / Collin Eagles-Smith

Why Dragonflies?

Over the course of a decade, the Dragonfly Mercury Project established a nationwide mercury monitoring network on public lands, using a robust and effective biomonitoring tool—dragonfly larvae. Most of a dragonfly’s life is spent in the larval stage underwater as a predator. Larvae are exposed to mercury that enters the food chain through their prey. Measuring mercury in these aquatic insects can reveal the extent of environmental mercury contamination.

Common in the environment and easy to collect, dragonflies are also charismatic insects that ignite public passion and enthusiasm. These qualities make them uniquely suitable as biosentinels and perfect for large-scale projects with hundreds of volunteers.

Where Is the Mercury?

In 2020, scientists from the U.S. Geological Survey, National Park Service, and other institutions published a study on the Dragonfly Mercury Project in the journal Environmental Science and Technology. It showed that mercury concentrations in dragonfly larvae were connected to those in fish and amphibians from the same locations. The paper’s authors developed an impairment index that uses the amount of mercury in larvae to show how mercury may affect other organisms. The impairment index builds on established toxicity thresholds for human and wildlife health. It reports mercury risk in defined categories, showing where dragonfly mercury concentrations are of potential concern for both human and wildlife health.

The study’s project team expanded the effort to more than 450 river, stream, lake, and pond locations between 2014 and 2020. The researchers found dragonfly mercury concentrations at low (31 percent of study sites), moderate (55 percent), or high (14 percent) levels. The distribution of data suggests that in 69 percent of the water bodies sampled, as measured by the impairment index, mercury in some fish species may exceed levels acceptable for human health. Across all national park study sites, the authors found varying levels of mercury. The highest mercury concentrations were at Maurice Wild and Scenic River (NJ) and Bear Meadows National Natural Landmark (PA). The lowest mercury concentrations were at Padre Island National Seashore (TX), Assateague Island National Seashore (MD), and a local city park, Bear Creek Lake Park (CO).

The exact reasons for variation in mercury concentrations across the landscape have puzzled scientists for decades. But we know mercury in food webs results from the relative amount of mercury in a watershed—in part due to its sources—and the processes that convert mercury to methylmercury. Whether from legacy contamination, urban effluent, present-day emissions, or geothermal features like volcanoes, loading rates—the amounts of mercury deposited in a watershed over a given time—vary. They depend on factors such as air transport patterns and proximity to source. Local environmental factors can also influence how much mercury ends up in organisms. For example, water chemistry can influence the availability of mercury for biological uptake. It can also induce certain microbes to convert inorganic mercury to methylmercury. Most of the mercury in dragonflies is methylmercury. Using them to assess ecosystem mercury can help determine the importance of sources and processes.

A chart of mercury concentration in national parks and other protected areas in the U.S. On the Y-axis is a list of protected areas. On the X-axis are concentrations of larval mercury. Insets show mercury proportions and a map of the areas.
Mercury concentrations in dragonfly larvae from protected places and NPS units across the contiguous U.S., Alaska, and Hawaii, 2014-2020. Inset pie chart depicts proportion of sites exceeding previously defined impairment indices: low (<100 ng/g dw), moderate (100-300 ng/g dw), and high (>300 ng/g dw). Inset map shows all units reporting data, 2014-2020. Map not to scale. NPS does not manage Bear Creek Lake Park and White Mountain National Forest. n/g dw = nanogram per gram dry weight.

Adapted from “A National-Scale Assessment of Mercury Bioaccumulation in U.S. National Parks Using Dragonfly Larvae As Biosentinels through a Citizen-Science Framework,” Eagles-Smith & others, Environmental Science & Technology, Vol. 54, No. 14, 8779-8790.

A National Project in a Global Initiative

Founded in 2010, the Dragonfly Mercury Project is led by the National Park Service and the U.S. Geological Survey. The program has expanded since its initial development with the University of Maine. It now includes the Appalachian Mountain Club, Dartmouth College, the U.S. Fish and Wildlife Service, and others. The project’s mission is fourfold:

  • Engage the public in hands-on, minds-on science
  • Provide actionable information about mercury risk reduction
  • Inform policy and resource management
  • Increase public understanding of the threats from mercury pollution

Through this program, diverse participants form a network of people with common interests. Participants have included resource managers, professional scientists, schools, and local community members. The network allows for nearly simultaneous data collection at a continental scale. Since the program’s inception, participants have sampled larvae in nearly 500 waterways spanning 47 states. The Dragonfly Mercury Project has shown the effectiveness of bringing different teams together under a common goal.

By 2020, roughly 5,000 people across the U.S. had participated, contributing more than 10,000 volunteer hours.

Partnerships are key to the success of large-scale ventures such as this one. What began as a pilot effort with four parks in 2010 grew into a research study that engages volunteers and includes more than 120 national parks and protected places. With each new park came more people. By 2020, roughly 5,000 people across the U.S. had participated, contributing more than 10,000 volunteer hours.

The domestic expansion of the Dragonfly Mercury Project has unique global implications: it could potentially solve a missing piece in the Minamata Convention on Mercury, an international treaty that aims to reduce mercury in the environment. One of the major questions asked by the treaty is whether mercury source reductions equate to decreases in environmental mercury. Dragonfly mercury can establish baseline conditions for tracking changes in environmental mercury through time to help answer that question.

Expansion through Networking

Because the Dragonfly Mercury Project is a citizen science project, it can readily expand through volunteers’ relationships across their communities. In addition to collecting and preparing larvae for analysis, participants help spread the word about the program. When a research project relies on its community to exist, its ability to extend its reach is enhanced. This is because collaboration is integral to the project’s design.

Kayla Fermin is a biological science technician with the National Park Service. She witnessed first-hand the networking opportunities that coincide with participation in the Dragonfly Mercury Project. A former intern and experienced leader of dragonfly larvae sample collection at Lewis and Clark National Historical Park, she engages other participants in this work.

“Interns stepped up their leadership by assisting the high school youth in [larvae] identification,” noted Fermin. Reflecting on her 2020 experience with the program, she said there was “enthusiastic engagement with all of the youth. A crew member drew a beautiful pencil sketch,” and “two others debated about what abiotic factors could have been impacting our collection numbers.”

A diagram of a tree. The brown roots are covered with agency logos. The branches and leaves are covered with partner logos.
A tree depicting the expansive, collaborative, and crowdsourced nature of the Dragonfly Mercury Project. Organizations internal to the study represent the root system. External partners embody the tree canopy.

Image credit: NPS. Logos used by permission of the respective agencies and organizations.

This collective enthusiasm contributes to the overall support for the Dragonfly Mercury Project in other nearby national parks, such as Olympic National Park. There, youth participants from NatureBridge started helping collect samples at Lake Crescent in 2012.

The Dragonfly Mercury Project continues to grow in scope and engagement. It creates thousands of citizen scientist experiences annually. It unites organizations within and across federal, academic, and nonprofit organizations. As of 2021, within the National Park Service alone, close to 50 individual program offices—regions, networks, parks, research learning centers, and friends’ groups—have supported the project.

Spreading Our Wings

Partnerships have helped the Dragonfly Mercury Project expand. This in turn has stimulated new connections. In 2013, the project partnered with the U.S. Geological Survey to determine the effectiveness of using dragonflies as mercury bioindicators. In 2016, the National Park Service’s centennial sparked renewed interest in connecting people with parks. Several partnerships began, including one with the National Natural Landmarks (NNL) Program. Since then, six natural landmarks have participated in the project.

"Collaboration on the Dragonfly Mercury Project enables managers to gain an understanding of where and how mercury may be negatively impacting trust resources."

A diagram depicting the 6 goals of the Dragonfly Mercury Prospectus.
Dragonfly Mercury Project partners include researchers, volunteers, resource managers, and more.

Image credit: NPS. Logos used by permission of the respective agencies and organizations.

"The NNL Program is excited to have national natural landmark sites engaged as partners in this landscape-scale project, some of which participated for the fifth season in 2021,” said Heather Eggleston, NNL Program Manager. “Their participation is not only contributing to the science to help understand the risks of mercury but strengthening connections between NNLs and the NPS."

Further, a multi-year partnership with the National Park Foundation began in 2018. It grew to include the U.S. Environmental Protection Agency and the U.S. Fish and Wildlife Service, through their participation in the Dragonfly Mercury Project Steering Committee. This interagency committee guides program development. The following year, the Appalachian Mountain Club and Dartmouth College joined, underscoring the program’s multi-organizational strengths.

The steering committee set its sights on building a sustainable future for the project. It outlined strategic actions and resources needed to maximize the benefits of the program. These are summarized in the Dragonfly Mercury Project Prospectus. The prospectus formalized the project’s multifaceted approach:

  • Benefit diverse partners by providing authentic research experiences for youth and other volunteers

  • Produce information that can be used to quantify mercury risk and inform resource management

The prospectus is the program’s most concerted effort to date to establish new partnerships. It aims to grow the value and impact of the Dragonfly Mercury Project.

Other federal agencies have expanded upon the National Park Service’s bottom-up approach to project recruitment. In 2020, the U.S. Forest Service and the Bureau of Land Management joined the Dragonfly Mercury Project. The following year, the U.S. Fish and Wildlife Service partnered with the project to better understand how mercury affects the often intensively managed habitats of the National Wildlife Refuge system. “Collaboration on the Dragonfly Mercury Project enables managers to gain an understanding of where and how mercury may be negatively impacting trust resources,” said Jennifer Wilkening, a research ecologist for the U.S. Fish and Wildlife Service.

"The students walk over the river so much that they don't see it." Getting in the water to collect larvae opened their eyes to a new way of connecting to nature and science.

For each land management agency, organization, or community that embarks on a partnership, additional collaborators connect with the study. In 2021, the Appalachian Mountain Club, Dartmouth College, and the U.S. Geological Survey launched the Merrimack-Dragonfly Mercury Project. This was a spinoff project with new local partners and teacher participants in the environmental justice communities of Lowell and Lawrence, MA. The partnership focuses on scientific literacy and engages parks in the Merrimack River Watershed, which has a legacy of mercury pollution.

The alliance involves at least 100 young people and community members, many of them visiting local green spaces for the first time. One teacher noted that in these river-centric towns, "The students walk over the river so much that they don't see it." Getting in the water to collect larvae opened their eyes to a new way of connecting to nature and science. Minute Man National Historic Park, Lowell National Historical Park, and the Sudbury, Assabet, and Concord Wild and Scenic Rivers are all in this watershed.

Highlighting Partners

The Dragonfly Mercury Project began a video series in 2021 to highlight its partnerships and projects. The series kicked off with a film featuring Citizens United to Protect the Maurice River and Its Tributaries (CU Maurice River for short). CU Maurice River is a nonprofit organization dedicated to protecting the Maurice River Watershed. Its volunteers collect dragonfly larvae in the Maurice River, which is a designated national wild and scenic river in New Jersey.

"Being able to educate that fish could be affected by mercury helps us protect habitats, but also human health."

CU Executive Director Karla Rossini explained the value of the project to the local community. “Any Friday or Saturday you can go down to the river, and you see people fishing for sustenance,” she said. “Being able to educate that fish could be affected by mercury helps us protect habitats, but also human health.” CU Maurice River is one of hundreds of partners that are essential to the Dragonfly Mercury Project’s success. Maurice Wild and Scenic River is managed by the National Park Service and is one of seven wild and scenic rivers participating in the project.

If You Want to Go Far

One of the earliest participating parks in the Dragonfly Mercury Project is Denali National Park and Preserve in Alaska. It is currently the program’s northernmost site. The park started collecting dragonfly larvae for mercury analysis in 2012. Denali Science and Resources Team Leader Dave Schirokauer said the project “provides critical insights into mercury contamination in seemingly pristine national parks.” He added that the program also engages the next generation and “furthers our understanding of how national parks can be influenced by industrial activities both near and far.”

"I had no idea there were so many tiny things that were so awesome living in the water all around us.”

Montana Conservation Corps member Madelline Morgan-Know helped collect data at Glacier National Park during the 2020 field season. “To be honest, I thought [collecting dragonfly larvae] would probably be boring,” she said. “But it’s turned out to be pretty mind blowing. I had no idea there were so many tiny things that were so awesome living in the water all around us.” Fellow corps member Jacob Tobia added, “I think everybody should probably do this to see and open your eyes to everything going on in the world—underneath or above water.”

The applicability of the program is underscored by the spectrum of participants, from scientists and land managers to youth, who support it. The continued growth of the Dragonfly Mercury Project will not only increase the global understanding of mercury pollution, but also expand alliances and foster new collaborations. Further, it will help us develop mercury mitigation techniques, promote scientific literacy, and foster environmental stewardship. The program’s success relies on its many partnerships. As the saying goes, “If you want to go fast, go alone; but if you want to go far, go together.” And it all began with one small insect, now a nationwide superhero.

About the authors

Colleen Flanagan-Pritz

Colleen Flanagan Pritz is an ecologist with the National Park Service, Air Resources Division, under the Natural Resource Stewardship & Science Directorate in Denver, CO. She is co-founder and program manager of the Dragonfly Mercury Project. Image courtesy of Colleen Flanagan-Pritz.

Katherine Ko

Katherine Ko is a biologist with the National Park Service, Air Resource Division, and program assistant on the Dragonfly Mercury Project. Image courtesy of Katherine Ko.

Collin Eagles-Smith

Collin Eagles-Smith is a research ecologist with the U.S. Geological Survey at the Forest and Rangeland Ecosystem Science Center in Corvallis, Oregon, and program co-lead of the Dragonfly Mercury Project. Image courtesy of Collin Eagles-Smith.

Sarah Nelson

Sarah J. Nelson is director of research for the Appalachian Mountain Club in Gorham, NH, and co-founder of the Dragonfly Mercury Project. Image courtesy of Sarah Nelson.

Assateague Island National Seashore, Denali National Park & Preserve, Glacier National Park, Lewis and Clark National Historical Park, Lowell National Historical Park, Minute Man National Historical Park, Olympic National Park, Padre Island National Seashore more »

Last updated: April 9, 2023