An abrupt ecosystem change in Lake Beloye, southern Western Siberia: Palaeoclimate versus local environment

An abrupt ecosystem change in Lake Beloye, southern Western Siberia: Palaeoclimate versus local environment

Sediment structure, rock-magnetic and bio-geochemical records obtained from sapropel core samples in Lake Beloye, southern Western Siberia, indicate an abrupt ecosystem change at 3.4 calibrated ka BP. The lake changed from eutrophic to oligotrophic, its vegetation — from carbon-fixing macrophytic an...

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Bibliographic Details
Published in:Palaeogeography, palaeoclimatology, palaeoecology Vol. 331-332; pp. 194 - 206
Main Authors: Krivonogov, Sergey K., Yamamuro, Masumi, Takahara, Hikaru, Kazansky, Alexey Y., Klimin, Mikhail A., Bobrov, Vladislav A., Safonova, Inna Y., Phedorin, Mikhail A., Bortnikova, Svetlana B.
Format: Journal Article
Language:English
Published: Elsevier B.V 01-05-2012
Subjects:
Biochemistry
Environmental changes
Geochemistry
Holocene
Rock magnetics
Sedimentology
Small lakes
Western Siberia
Sedimentology
Rock magnetics
Small lakes
Geochemistry
Environmental changes
Biochemistry
Western Siberia
Holocene
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Summary:Sediment structure, rock-magnetic and bio-geochemical records obtained from sapropel core samples in Lake Beloye, southern Western Siberia, indicate an abrupt ecosystem change at 3.4 calibrated ka BP. The lake changed from eutrophic to oligotrophic, its vegetation — from carbon-fixing macrophytic angiosperms to calcium-fixing macrophytic algae and angiosperms, and, as a result, the type of sedimentation shifted from peaty sapropel to carbonate-rich sapropel. Those changes could be induced by climate, which was warmer and wetter before 3.4ka BP and cooler and drier after this. Nevertheless, our data show that those ecosystem changes occurred when the lake became shallower to get about 1m depth and started to freeze to the bottom in winter time. The full freezing of the lake led to the deposition of carbonates, which resulted in: i) death of carbon-utilizing macrophytic angiosperms; and ii) winter precipitation of calcium carbonate. In summer, additional portions of Ca2+ and HCO3− ions come into the lake from the surrounding CaCO3 rich loess sediments with ground water. The Beloye Lake thus represents an example of interrelated regional climatic and local ecological factors, which combination resulted in the 3.4cal. ka BP dramatic change of its ecosystem. ► An abrupt ecosystem change occurred in Lake Beloye at 3.4cal. ka BP. ► The lake changed from eutrophic to oligotrophic. ► Its vegetation changed from carbon-fixing to calcium-fixing. ► Sedimentation changed from peaty sapropel to carbonate-rich one. ► Lake's winter full-freezing broke its ecosystem.
ISSN:0031-0182
1872-616X
DOI:10.1016/j.palaeo.2012.02.030