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A diatom-based Holocene palaeoenvironmental record from a mid-arctic lake on Boothia Peninsula, Nunavut, Canada

Department of Geography, University of Ottawa, Ottawa, ON K1N 6N5, Canada

K. Gajewski

Department of Geography, University of Ottawa, Ottawa, ON K1N 6N5, Canada, gajewski{at}aix1.uottawa.ca

P. B. Hamilton

Canadian M useum of Nature, Research Division, PO Box 3443, Station D, Ottawa, ON K1P 6P4, Canada

A 485 cm sediment core from a lake unoffcially called JR01, Boothia Peninsula, Nunavut, Canada, yielded a high-resolution diatom record documenting environmental change in the mid-arctic. Five radiocarbon dates provided the chronology. Changes in diatom composition and sediment character istics indicated distinct shifts in the Holocene climate. A more diverse and productive diatom flora implies warmer temperatures in the middle Holocene. A subsequent complete shift in diatom composition to a predominantly Fragilaria sensu lato flora and a reduction in diversity and production suggests cooler climates in this region after 4600cal. BP. Smaller-scale climatic fluctuations, such as the‘Little Ice Age’ (LIA, 600–150 cal. BP) and the‘Mediaeval Warm Period’ (MWP, 1150–600 cal. BP), caused shifts in the diatom flora and production. Subtle shifts in floristic diversity within the LIA may reflect climatic variability at a century scale. A gradual shift to a more diverse and productive flora in the last 150 years suggests a response to the recent warming trend.

Key Words: Diatom • arctic • lake sediments • climate change • ‘Little Ice Age’ • Holocene • Canada

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