Diatom-inferred lake level from near-shore cores in a drainage lake from the Experimental Lakes Area,northwestern Ontario,Canada |
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Authors: | Kathleen R Laird Brian F Cumming |
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Institution: | (1) Paleoecological Environmental Assessment and Research Laboratory (PEARL), Department of Biology, Queen’s University, Biosciences Complex, 116 Barrie St., Kingston, ON, Canada, K7L 3N6 |
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Abstract: | We inferred late Holocene lake-level changes from a suite of near-shore gravity cores collected in Lake 239 (Rawson Lake),
a headwater lake in the Experimental Lakes Area, northwestern Ontario. Results were reproduced across all cores. A gravity
core from the deep central basin was very similar to the near-shore cores with respect to trends in the percent abundance
of the dominant diatom taxon, Cylcotella stelligera. The central basin, however, does not provide a sensitive site for reconstruction of lake-level changes because of the insensitivity
of the diatom model at very high percentages of C. stelligera and other planktonic taxa. Quantitative estimates of lake level are based on a diatom-inferred depth model that was developed
from surficial sediments collected along several depth transects in Lake 239. The lake-level reconstructions during the past
~3,000 years indicate that lake depth varied on average by ±2 m from present-day conditions, with maximum rises of ~3–4 m
and maximum declines of ~3.5–5 m. The diatom-inferred depth record indicates several periods of persistent low levels during
the nineteenth century, from ~900 to 1100 AD, and for extended periods prior to ~1,500 years ago. Periods of inferred high
lake levels occurred from ~500 to 900 AD and ~1100 to 1650 AD. Our findings suggest that near-shore sediments from small drainage
lakes in humid climates can be used to assess long-term fluctuations in lake level and water availability. |
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Keywords: | Experimental Lakes Area Northwest Ontario Lake level Drought Diatoms Organic matter Transfer function |
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