Analysis of Diatom Algae of the Water Column and Bottom Sediments of Lake Shira
G. N. BOLOBANSCHIKOVA1, D. Yu. ROGOZIN1,2, A. D. FIRSOVA3, E. V. RODIONOVA3, N. N. DEGERMENGI4, A. V. SHABANOV5
1Institute of Biophysics SB RAS, 660036, Krasnoyarsk, Akademgorodok str., 50/50
2Siberian Federal University, 660041, Krasnoyarsk, Svobodny ave., 79
3Limnological Institute SB RAS, 664033, Irkutsk, Ulan-Batorskaya str., 3
4Krasnoyarsk State Medical University nаmed after V. F. Vojno-Yasenetsky, 660022, Krasnoyarsk, Partizanа-Zheleznyaka str., 1
5L. V. Kirensky Institute of Physics SB RAS, 660036, Krasnoyarsk, Akademgorodok str., 50/38
Keywords: paleolimnology, diatoms, meromictic lake, sedimentation, Cyclotella choctawhatcheeana, Aulacoseira valida, Aulacoseira ambigua
Abstract
Meromictic lakes are interesting objects for paleolimnological study, and Lake Shira is one of such lakes. In May 2011 core samples were collected from the bottom of Lake Shira and the species composition of diatom algae, which serve as bioindicators of the state of the lake, were studied. Moreover, in the year 2012 seasonal water samples and material from sediment traps were collected and the species composition of diatoms in them was analyzed. The results of the analysis showed that the lake, as in previous years of research, was dominated by Cyclotella choctawhatcheeanа Prasad. Diatoms were found twice in the studied core, above the white carbonate layers and were absent in other layers. Down to the first white layer the species living in the lake at present time were observed, including the predominant Cyclotella choctawhatcheeana. This fact, presumably, proves the consistency of the species composition of diatoms and the overall stable condition of the lake since 1946 [Popova, 1946]. Down to the second white carbonate layer the dominant species were Aulcosira valida (Grunow) Krammer and Aulcosira italica (Grunow) Simonsen. Besides them, Nitzchia sigmodea (Nitzsch) W. Smith, Fragilaria construens var. venter (Ehrenberg) Grunow were also observed at these depths, dating approximately to 1655-1690. These are freshwater species that belong to the diatoms of arctic, alpine and temperate latitudes which develop in shallow waters under moderate temperature conditions. This fact suggests that Lake Shira was less salty in the middle and the end of the 17th century than today.
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