• The Florida panther's steely gaze - NPS/RALPH ARWOOD

    Big Cypress

    National Preserve Florida

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  • Secondary Trail Closure

    As part of a settlement agreement with plaintiffs related to the designation of secondary off-road vehicle trails, all secondary off-road vehicle trails are closed until further environmental review and analysis can be completed. More »

  • October Off-Road Vehicle Advisory Committee Meeting Cancelled

    The National Park Service at Big Cypress National Preserve has cancelled the off-road Vehicle Advisory Committee meeting that was scheduled for Tuesday, October 7. More »

Determining Mercury Levels through Dragonfly Nymphs


Mercury (Hg), a natural element, is held within rocks. However, it is released into the atmosphere primarily through human activities, such as burning coal. Mercury is then carried by winds, eventually returning to the earth's surface by gravity or rain.

When Mercury is deposited or flows into wetlands, it is converted by bacteria into a toxin. Over time, this toxin bioaccumulates in animals, reaching potentially deadly levels in top predators.


How much mercury exists within our national parks? First, researchers from the University of Maine determined that aquatic dragonfly nymphs, the juvenile stage of adult dragonflies, contain mercury levels representative of their wetland environments. The researchers then collaborated with scientists at the National Park Service Air Resources Division to create a citizen science program investigating mercury levels in the national parks. National park units recruited volunteers, known as citizen scientists, to collect dragonfly nymphs for analysis.


Eighth grade students busy collecting data.

At Big Cypress National Preserve, 8th grade students from Seacrest County Day School searched the swamp for samples. During the winter of 2012, 27 dragonfly nymphs from three sites within Big Cypress were collected and sent to the University of Maine for analysis. On average, Big Cypress dragonfly nymphs did contain elevated levels of mercury compared to other parks.

Mercury concentrations were found to vary from one National Park Service unit to another, with eastern units generally containing higher mercury levels than western units. Data from some units revealed high variability within parks as well.

Seacrest students continued the study, returning for its second year. They collected 54 dragonfly nymphs from four sites across Big Cypress National Preserve during the winter of 2013. Results from 2014 samples are expected in the spring.



For a downloadable PDF of the summary of results, click here.

For an informative YouTube video about this fascinating project, please click here.

For teachers interested in incorporating mercury into their curriculums, please click here for resources.

Did You Know?

Many large trees that did exist were harvested in the early 1900s.

There are few "big cypress" in Big Cypress National Preserve. The name actually refers to the great expanse of cypress forest, hundreds of thousands of acres, within the Big Cypress Swamp.