The Dragonfly Mercury Project is a nationwide program that pairs scientific efforts to understand mercury pollution risks with citizen engagement and education. Dragonfly larvae serve as indicators of mercury, a toxic pollutant, in aquatic food webs. Click on the map below to find information about mercury levels in dragonfly larvae from sampling sites in participating parks. Project-wide data are available for download from the U.S. Geological Survey Science Base Catalog.
Dragonfly Mercury Project Data 2014-2018
Wildlife risk benchmarks indicate levels above which animals consuming them may be affected by mercury. Preliminary analyses suggest that dragonfly larvae with mercury concentrations above around 300 ppb, dry weight may pose toxicological risks to fish and wildlife that consume them or their predators. This proposed benchmark - denoted by the red, dashed, horizontal line in the bar chart - reflects potential toxicological risk to fish and wildlife based on a combination of published effects thresholds and trophic enrichment factor estimates. It is important to note that this benchmark only addresses potential risk to fish or wildlife that directly consume dragonflies and likely underestimates risk to fish-eating fish because of food web biomagnification. Expanding the analysis beyond direct dragonfly consumers would require site-specific information on food web structure and community composition. Please keep these considerations in mind when interpreting environmental health risk.
Last updated: May 29, 2020