Assessment of freshwater diatoms as quantitative indicators of past climatic change in the Yukon and Northwest Territories,Canada |
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| Authors: | Reinhard Pienitz John P Smol H John B Birks |
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| Institution: | (1) Paleoecological Environmental Assessment and Research Laboratory (PEARL), Department of Biology, Queen's University, K7L 3N6 Kingston, Ontario, Canada;(2) Botanical Institute, University of Bergen, Allégaten 41, N-5007 Bergen, Norway;(3) Environmental Change Research Centre, University College London, 26 Bedford Way, WC1H OAP London, UK;(4) Present address: Centre d'études nordiques et départment de géographie, Université Laval, Québec, G1K 7P4 Québec, Canada |
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| Abstract: | We identified, enumerated, and interpreted the diatom assemblages preserved in the surface sediments of 59 lakes located between Whitehorse in the Yukon and Tuktoyaktuk in the Northwest Territories (Canada). The lakes are distributed along a latitudinal gradient that includes several ecoclimatic zones. It also spans large gradients in limnological variables. Thus, the study lakes are ideal for environmental calibration of modern diatom assemblages. Canonical correspondence analysis, with forward selection and Monte Carlo permutation tests, showed that maximum lake depth and summer surface-water temperature were the two environmental variables that accounted for most of the variance in the diatom data. The concentrations of sodium and calcium were also important explanatory variables. Using weighted-averaging regression and calibration techniques, we developed a predictive statistical model to infer lake surface-water temperature, and we evaluated the feasibility of using diatoms as paleoclimate proxies. This model may be used to derive paleotemperature inferences from fossil diatom assemblages at appropriate sites in the western Canadian Arctic. |
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| Keywords: | diatoms temperature climatic change paleoclimate proxies canonical correspondence analysis weighted-averaging Yukon Northwest Territories |
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