Stevens High School Students Collect Dragonflies to Study Mercury Levels in Aquatic Ecosystems
Robin Tymula, Environmental Science teacher at Stevens High School in Claremont, brought her students out to Sullivan County's Marshall Pond Property to collect dragonfly nymphs for the Twin States Mercury Project, part of a larger national project that started in 2011 to assess the level of mercury in aquatic ecosystems.
The project was started through a partnership between the National Park Service, US Geological Survey, the University of Maine, and a few other labs, including Dartmouth College, because of growing concerns about the amount of toxins coming out of coal-burning power plants accumulating in ecosystems through atmospheric deposition (air pollution). Air pollutants can travel long distances before they settle at ground level. In aquatic ecosystems, some mercury can be transformed from an inorganic form to an organic form by microbial processes. The organic form, methylmercury, is a neurotoxin and endocrine disruptor that affects the health of humans and wildlife.
Dragonfly nymphs were chosen, because can live for 7-9 years in aquatic ecosystems, so they build up higher levels of toxins than other insects. They are in the middle of the food chain and are easy to collect. Fish eat dragonfly larva and accumulate even higher levels of mercury, but are harder to catch and large to process.
Armed with nets, buckets and water quality testing equipment, Tymula's students hiked down to Marshall Pond. They collected water samples and caught dragonflies from muddy areas near the shoreline. The dragonflies were then cleaned, identified to family, and placed in clear plastic bags for transport to Dartmouth College where they will be processed and the level of mercury accumulated in their bodies will be measured.
These students will get the results of this testing this fall and will create a scientific poster to share their findings. Other Upper Valley schools that have also participated in this study will do the same thing and they will all come together at a poster session documenting the students’ research this winter. Many schools have been collecting data for the Twin States Mercury Project for years now and are able to share patterns or trends that they have noticed in specific bodies of water.
This project allows high school students to use scientific practices to investigate human impact on aquatic ecosystems and communicate what they have learned with others. If you would like to use Sullivan County Lands as a field study site for your students, be sure to contact us.