HOLOCENE REGIONAL CLIMATE INFERRED FROM DIATOM ASSEMBLAGES OF YELLOWSTONE LAKE

As the largest alpine lake in North America, Yellowstone Lake provides a unique opportunity for multi-proxy regional climate reconstruction. Long-term climate records provide context for modern climate changes. Reconstructing past climate and ecological responses to various conditions is vital to modeling and preparing for manifestations of modern climate change. The objective of this study is to reconstruct the Holocene climate of Yellowstone Lake utilizing diatom assemblage changes. An 11 m sediment core was collected from the northern basin of Yellowstone Lake in September 2016. Diatoms were enumerated at high resolution throughout the core using standard methods. The record is dominated by planktonic species including Aulacoseira subarctica, Stephanodiscus yellowstonensis, Stephanodiscus minutulas, and Asterionella Formosa. S. yellowstonensis and A. subarctica maxima are associated with low N:P ratios and drought periods. S. yellowstonensis, which blooms in summer, outcompetes S. minutulas under conditions of high light and low nutrients. Potential drivers for species abundance include changes in mixing depth and allochthonous input.