Temperature and Dragonfly Larvae Mercury Levels. B. Beaudoin , R. Geiger, G. Zito.
B. Beaudoin, R. Geiger, G. Zito
The objective of the experiment was to determine if the temperature affects the mercury concentration in dragonfly larvae in national parks across the United States. Our hypothesis stated that dragonflies living in national parks with warmer climates would have a higher mercury concentration due to the bacteria responsible for methylation thriving in optimal temperatures. The data on the graph shows that national parks with warmer climates contain dragonflies that have higher mercury concentrations, and the colder the national park, the lower the mercury concentrations in the dragonflies. The averages of these parks ranged from around 38 ppm wet weight in Big Cypress to around 8 ppm wet weight, in North Cascade.The mercury concentrations ranged from 9.2 ppm wet weight to 40.2 ppm wet weight, and the parks varied from a warm and wet climate in Florida to a frosty, elevated climate in Alaska. We also had two data points that were outliers. According to the data, the frigid heights of Alaska yielded more mercury than the more temperate park in Washington. This may be caused by pollution from China drifting up into Alaska, or mercury coming to rest and becoming inert in the heavy soil of the mountains. Also, high rising mountains could catch mercury drifting in the atmosphere. In Washington, mercury could be spread out more due to violent storms. Some limitations in our data was the quantity of readings and the quantity of parks. If there were more parks tested that covered more of the United States property, the data would have been more accurate. Overall, the relationship between mercury concentration and temperature showed that national parks with warmer climates tend to have dragonflies with a higher mercury concentration than national parks with cooler climates.
This study is important because it brings awareness to a current and pressing situation. As you may have heard, there is methylmercury in the environment. The mercury collects in anaerobic conditions through runoff, wet deposition, and dry deposition, and then gets converted by bacteria to a highly toxic form called methylmercury. Us, as a group chose to research methylmercury in the environment because it seemed interesting and we could easily relate to that topic because mercury is in the environment where we live. Some background information that we have on this topic was a presentation from a scientist at Dartmouth and a few research assignments during science class. During our research assignments we found that bacteria prefer warmer climates (The Fascinating World of Bacteria). Bacteria also like climates that are moist and have slowly moving water (Chemical of the Week). We then decided to look at how much mercury different national parks across the United States had, using dragonfly larvae as an indicator species. We chose Big Cypress(FL), Denali(AL), Saint Croix(WI), Acadia(ME), and North Cascade(WA), due to their spread out placement across the U.S.
Mercury Concentration (ppb, ww) in National Parks
A special thanks goes out to Dartmouth College, University of Maine, Acadia National Park, Marsh Billings Rockefeller National Historical Park, Big Cypress National Park, Denali National Park, North Cascade National Park, Saint Croix National Park, and the National Park Service for helping us with our research.
"The Fascinating World of Bacteria." The Fascinating World of Bacteria. Home Training Tools, Ltd, 2013. Web. 25 Nov. 2013.
"Chemical of the Week -- Mercury." Chemical of the Week -- Mercury. N.p., n.d. Web. 25 Nov. 2013.
Students from Woodstock Union High School went to Marsh Billings Rockefeller National Historical Park (MBRNHP) to collect dragonfly larvae. After collecting the data the students sent their findings to Dartmouth College for them to be tested. At Dartmouth the larvae were tested for their mercury level and concentration. Other data that is being used in this project came from Acadia, Big Cypress, Denali, North Cascade, and Saint Croix National Parks. We used one site’s data from every park. All of the information collected from the parks was sent to the University of Maine where it was processed.
Materials and Methods