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  • 1
    ISSN: 1573-0417
    Keywords: diatoms ; temperature ; climatic change ; paleoclimate proxies ; canonical correspondence analysis ; weighted-averaging ; Yukon ; Northwest Territories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: diatoms ; limnology ; paleolimnology ; canonical correspondence analysis ; weighted-averaging ; dissolved organic carbon ; dissolved inorganic carbon ; subartic ; treeline ; Northwest Territories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between diatom (Bacillariophyceae) taxa preserved in surface lake sediments and measured limnological and environmental variables in 22 lakes near Yellowknife (N.W.T.) was explored using multivariate statistical methods. The study sites are distributed along a latitudinal gradient that includes a strong vegetational gradient of boreal forests in the south to arctic tundra conditions in the north. Canonical correspondence analysis (CCA) revealed that lakewater concentrations of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) each accounted for independent and statistically significant proportions of variation in the distribution of diatom taxa. Weighted-averaging (WA) models were developed to infer DIC and DOC from the relative abundances of the 76 most common diatom taxa. These models can now be used to infer past DIC and DOC concentrations from diatom assemblages preserved in sediment cores of lakes in the Yellowknife area, which may provide quantitative estimates of changes in lakewater chemistry related to past vegetational shifts at treeline.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 173 (1989), S. 231-242 
    ISSN: 1573-5117
    Keywords: rotifers ; high arctic linmology ; Ellesmere Island ; Northwest Territories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five small ponds on Cape Herschel, Ellesmere Island, N.W.T. (latitude 78° 37′ N; 74° 42′ W) were investigated, and their rotifer fauna discussed. Although the number of individuals is very low, the rotifer assemblage is remarkably rich (33 species), especially considering the harsh environmental conditions, and the short ice-free period of only six weeks. The shallow ponds are all alkaline, and the rotifer species are either cosmopolitan, or very rare. Proales kostei n. sp. is described.
    Type of Medium: Electronic Resource
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