The Secret History of Bagley Basin: Snow Algae and the Millennia Long Story They Tell

Alpine Lake sediments can preserve biological records of organisms that live in or on seasonally snow-covered lakes whose biomass sinks and is deposited over time. These organisms include snow algae that grow on the surface of alpine lakes in the late spring and early summer. Bagley Lake in the North Cascade Mountains is a site that has regular recurring snow algae blooms. A sediment core from Bagley Lake was examined to determine the changes in snow algae diversity and abundance over the past few millennia. Microfossils in the laminated sediments of the cores include snow algae, diatoms, testate amoebae and other unidentified cells. Analysis of the core by scanning electron microscopy and carbon-14 radioisotope dating indicates that the abundance and diversity of all these groups of microfossils has varied substantially over the past 2700 years. Historic photos and sedimentologic evidence (e.g., clastic laminae) indicate that a small cirque glacier likely existed in the Bagley Lake Basin for nearly the entire time period represented by the core, only disappearing in the last ca. 70 years. This glacial history may allow us to reconstruct the ecological history of snow algae in this area as well their response to the demise of the glacier historically. (This abstract is published as a placeholder for work that will be submitted for publication elsewhere. The eventual publication will be linked back to this page.)