UNDERGRADUATE LACUSTRINE RESEARCH FOCUSING ON ENVIRONMENTAL CHANGE AT GLACIER NATIONAL PARK, MONTANA

Glacier National Park, Montana (GNP), is sensitive to environmental changes from natural and human forcing, yet because few lacustrine records from the northern U.S. Rockies spanning the entire Holocene, our knowledge of the timing and causes of major environmental shifts in this region are incomplete. In summer 2010, a research team of seven undergraduate students and several faculty and researchers, sponsored by the Keck Geology Consortium, collected sediment cores in three lakes located downstream of Grinnell Glacier, following up on previous research conducted in 2005. Each student then worked on an independent research project at his/her home institution during the 2010-11 academic year. Several projects that focused on a continuous core from Swiftcurrent Lake spanning over 12,900 years demonstrate a strong link between global climate and local ecosystem responses in GNP, including changes in forest composition, charcoal abundance, total carbon flux, and biogenic silica (i.e., diatom) production. Two additional studies focused on changes over the timescale of the National Park, founded in 1910, using lead-210-dated records. One established a strong correlation between clastic sedimentation rates and the retreat record of Grinnell Glacier, demonstrating faster deposition rates when the glacier was larger. The other study found geochemical signatures of human impacts near the Many Glacier Hotel, one of the oldest lodges in the park. For example, δ¹⁵N measurements indicate changes in the nitrogen cycle from septic systems associated with a nearby campground from the 1930s to 1970s. Anthropogenic influences can be separated from natural background effects by comparison of the core taken near the hotel with another dated core collected near the inlet of the same lake. Three large historic floods are also distinguishable in the C/N and δ¹³C records, likely because of influx of terrestrial biomass. Our results provide important constraints on both natural and anthropogenic change in GNP. Natural processes affecting lake sedimentation include glacial erosion, forest fires, and flooding. Human activities that have a primary effect on lake chemistry include land use changes (e.g., deforestation and lakeshore development), increased traffic, and changing strategies for wastewater management.