A sampling methodology for citizen scientists allowed the team to complete the most comprehensive assessment of mercury contamination and environmental risk of protected lands to date. Dragonflies were sampled from 100 U.S. national parks and other protected places, including very remote areas. Thirty-two percent of sites had mercury exposure that posed low risk to fish, wildlife, or humans; however, 12 percent of sites had mercury concentrations associated with a high level of impairment risk. Flowing waters – rivers and streams – had higher mercury concentrations than still waters – ponds and lakes. Mercury concentrations in sites bounded by wetlands were 37 percent higher than those without wetlands. The study shows how the nation’s citizenry can be engaged in meaningful research that provides community learning and scientific contributions at an exceptional cost savings compared to more common approaches. 

Eagles-Smith, C.A., Willacker Jr., J.J., Nelson, S.J., Flanagan-Pritz, C.M., Krabbenhoft, D.P., Chen, C.Y., Ackerman, J.T., Grant, E.H., Pilliod, D.S., 2020, A national-scale assessment of mercury bioaccumulation in United States National Parks using dragonfly larvae as biosentinels through a citizen-science framework: Environmental Science and Technology, http://dx.doi.org/10.1021/acs.est.0c01255