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| Titel |
Sub-fossil cladoceran remains from the sediment of the lakes in Arctic Siberia, Russia: relationship to physical and chemical variables |
| VerfasserIn |
Larisa Frolova, Larisa Nazarova, Ulrike Herzschuh |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042527
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| Zusammenfassung |
| The lakes examined in this study are located on the catchment area of Anabar river in the
north-west part of Yakutia (Russia), just west of the Lena River. All presented samples and
data were obtained in frame of a joint Russian–German expedition to Yakutia in summer
2007. The study sites included 35 lakes that were distributed along a broad north–south
transect across northwest Yakutia, Russia, ranging from latitude 71Ë 50′ to 73Ë 39′. This
transects captures considerable changes in geology, vegetation, and climate. The studied lakes
are shallow thermokarst lakes with maximal depths of about 10 m (mean 4.27±0.76). The
waters were dominated by Ca–Mg, Fe and HCO3, but the ion concentration was generally
low in all studied waters.
From the initial 35 localities, only 31 contained a sufficient number of cladoceran remains
for reasonable quantification. From these, a total of 28 cladoceran taxa representing 14 genera
were identified, comprising predominantly littoral chydorid species. Species richness (i.e. the
total number of taxa per lake) ranged between 5 (07-SA-05, 07-SA-14, 07-SA-18) and 20
(07-SA-24), with a mean of 9, and was not significantly correlated with any of the measured
environmental variables.
With forward selection and Monte Carlo permutation tests (999 permutations), RDA
identified a minimal subset of four environmental variables that explained a significant (p -¤
0.05) amount of the variation in the species data. These variables are TJuly, water depth,
SO42-, Si4+. RDA axis 1 (λ = 0.174) and axis 2 (λ = 0.157) were both significant and
explained almost all of the relationships between the cladoceran taxa and measured
environmental variables (85.8%).
Distributions of the cladoceran taxa, however, revealed major shifts in abundance in
relation to the temperature along our transect. Constrained cluster analysis (CONISS), based
on the structure of cladoceran community, disclosed three groups of lakes in the tundra and
forest-tundra zones of the north-western part of Yakutia. Frontiers of divisions, separated on
the basis structure of sub fossil cladoceran assemblages along a temperature gradient
completely coincided with landscape zoning on the basis vegetative communities (typical
tundra, southern tundra, forest-tundra). |
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