| Title |
Stratified Distribution of Nutrients and Extremophile Biota within Freshwater Ice Covering the Surface of Lake Baikal |
| Author |
Nina A. Bondarenko1*, Olga I. Belykh1, Ludmila P. Golobokova1, Olga V. Artemyeva1, Natalia F. Logacheva1, Irina V. Tikhonova1, Irina A. Lipko1, Tatyana Ya. Kostornova1, Valentina V. Parfenova1, Tamara V. Khodzher2, and Young-Gun Zo3 |
| Address |
1Limnological Institute, Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya, 3, 664033 Irkutsk, Russia, 2Depatment of Environmental Science Kangwon National University, Chunchon 200-701, Republic of Korea, 3Depatment of Biology, Kyungsung University, Busan 608-736, Republic of Korea |
| Bibliography |
Journal of Microbiology, 50(1),8-16, 2012,
|
| DOI |
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| Key Words |
freshwater ice, chemical composition, ice organisms, picoplankton, actinomycetes, diatoms |
| Abstract |
Biological entities and gradients of selected chemicals within
the seemingly barren ice layers covering Lake Baikal were
investigated. Ice cores 40–68 cm long were obtained from
inshore and offshore sites of Southern Lake Baikal during
the cold period of a year (March-April) in 2007 and 2008.
In microscopic observations of the melted ice, both algae
and bacteria were found in considerable numbers (>103
cells/L and >104 cells/ml, respectively). Among all organisms
found, diatom was generally the most predominant taxon
in the ice. Interestingly, both planktonic and benthic algae
were present in considerable numbers (2–4×104 cells/L).
Dominant phototrophic picoplankton were comprised of
small green algae of various taxa and cyanobacteria of
Synechococcus and Cyanobium. The bacterial community
consisted mostly of short rod and cocci cells, either freeliving
or aggregated. Large numbers of yeast-like cells and
actinomycete mycelium were also observed. Concentrations
of silica, phosphorus, and nitrate were low by an order of
magnitude where biota was abundant. The profile of the ice
could be interpreted as vertical stratification of nutrients and
biomass due to biological activities. Therefore, the organisms
in the ice were regarded to maintain high activity while
thriving under freezing conditions. Based on the results, it
was concluded that the freshwater ice covering the surface
of Lake Baikal is considerably populated by extremophilic
microorganisms that actively metabolize and form a detritus
food chain in the unique large freshwater ecosystem of
Lake Baikal. |
