Dragonfly larvae are biosentinels of mercury risk to ecosystems because they are widespread, abundant, easy to collect, and represent exposure in fish and wildlife. As part of the Dragonfly Mercury Project, researchers collected dragonfly larvae from 21 sites in Olympic National Park in Washington and Acadia National Park in Maine to look at seasonal and annual variation in dragonfly mercury. Larvae were collected four times per year, from spring to fall, over two years. Differences in mercury concentrations among sampling events were small, suggesting that timing of sampling at a particular site is not likely to impact spatial patterns of mercury contamination in parks. Monitoring tools, such as the use of dragonfly larvae as biosentinels, are needed to assess if global effort to reduce mercury emissions also reduce mercury in the environment.  

Willacker Jr., J.J., Eagles-Smith, C.A., Nelson, S.J., Flanagan-Pritz, C.M., and Krabbenhoft, D.P., 2023, The influence of short-term temporal variability on the efficacy of dragonfly larvae as mercury biosentinels: Science of the Total Environment, v. 867, 161469. https://doi.org/10.1016/j.scitotenv.2023.161469