Bio-sentinels of Mercury in Freshwater Ecosystems: The role of dragonflies

Mitchell Center scientist Sarah Nelson has been working with National Park staff to coordinate sampling of dragonfly larvae across the U.S. parks, leading field trips to sample dragonflies and water, and shipping samples to UMaine for laboratory analysis at the Sawyer Environmental Chemistry Research Lab. For the past five years, she has worked with agencies and organizations such as SERC Institute and Maine Sea Grant to develop educational programs that put teachers and students into the field as front line researchers, help that lead to this Park-wide project. This program is vital to the discussion if dragonfly larvae can serve as indicators of ecosystem health by characterizing the risk and transfer of mercury around food webs. These aquatic insects build up high levels of mercury because they are predatory and are long-lived underwater. Dragonfly larvae are also widespread across the U.S., allowing comparisons among parks.

Earlier this month the National Park Service awarded Nelson another grant to expand her research on dragonfly larvae. The project will include working with Citizen Scientists in 25 parks during 2013 to help collect larvae samples in spring/early summer, and later in the summer/fall. “Our work continues using dragonfly larvae (immature dragonflies, which live in the water for the first year(s) of their lives) as bio-sentinels to help us understand which types of watersheds and water-bodies seem to have greater mercury” says Nelson. “The work will expand our understanding of mercury sensitivity in water bodies and their food webs, and provide data to determine if dragonfly larvae are useful indicators of that sensitivity”.

The University of Maine has produced a video on the project that is available online.