The Question: Is atmospheric deposition of nitrogen to park lakes changing algae communities?
The alpine lakes in the park are generally thought of as undisturbed ecosystems. There is, however, considerable evidence based on more than 20 years of study that a signifi cant amount of anthropogenic (i.e., originating from human activities) nitrogen is being deposited through rain and snow falling on the park. Sources of nitrogen include motor vehicles, power plants, factories, oil and gas wells, fertilizer, and animal feedlots. Significant emissions from all of these sources are transported in air masses from the Front Range urban corridor and other locations to the park. Past research eff orts have linked changes in the chemistry of park soils and Engelmann spruce needles to rising anthropogenic nitrogen inputs. This study investigated whether changes in diatom species and abundance occurred as a result of anthropogenic nitrogen deposition. Diatoms, a type of algae, have cell walls made from silica (just like window glass). Individual species are very sensitive to specific changes in water chemistry making them excellent indicators of water quality. They can remain in lake sediments as identifi able organisms for thousands of years. Distinctive shapes make identification relatively easy. Dr. Alex Wolfe of the University of Alberta, Edmonton, Canada, was the lead investigator.