Holocene paleoenvironmental changes inferred from diatom assemblages in Kusawa Lake, Yukon Territory, Canada

Diatom community composition and primary production in Kusawa Lake, Yukon Territory, Canada, over the Holocene were assessed and related to inferred environmental variables in order to determine the factors responsible for influencing species assemblages in a large, deep, sub-Arctic lake. The Kusawa Lake record was dominated by planktonic species with Cyclotella ocellata and Cyclotella pseudostelligera showing the highest abundances throughout the record. Holocene temperature changes as inferred from pollen data, ice core data, and oxygen isotope values, were found to influence changes in diatom community composition and were positively related to primary production. The peaks in diatom primary production and species diversity observed in the Kusawa Lake record indicate that the end of the Holocene Thermal Maximum (HTM) occurred around 7,000 cal. BP in the southwest Yukon region.