The Adirondack Lakes Survey Corporation (ALSC) recently completed collections of dragonfly larvae in acid rain sensitive Adirondack surface waters. ALSC staff assisted Mitchell Center assistant research professor Sarah Nelson, and collaborators at the SERC Institute, Maine Sea Grant, the USGS Mercury Research Lab, and Dartmouth College, who have been developing the concept of using dragonfly larvae as bio-sentinels for mercury concentrations in northeast lakes and streams. Mercury is a natural element but is found in elevated levels in Maine and many locations across the country due largely to fossil fuel emissions. Scientists are unable to predict which lakes or streams might have high or low mercury because it has a complex cycle both getting to waterbodies and once it’s in the water. “Our work has been 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 waterbodies seem to have greater mercury” says Sarah. “The work will help us understand if we can model mercury sensitivity in lakes and their food webs, and if dragonfly larvae are good indicators of that sensitivity”.