DISTRIBUTION OF DIATOMS IN SURFACE SEDIMENTSOF LAKE BAIKAL
E.V. Likhoshway, G.V. Pomazkina, A.O. Kostyukovskaya, V.N. Sergeeva, and O.V. Levina*
Limnological Institute, Siberian Branch of the RAS, 3 ul. Ulan-Batorskaya, Irkutsk, 664033, Russia
* Institute of Geochemistry, Siberian Branch of RAS, 1a ul. Favorskogo, Irkutsk, 664033, Russia
Keywords: Diatoms, surface sediments, biogenic silica, Lake Baikal
Pages: 34-49
Abstract
Contributions of various diatom species to deposition were investigated in surface sediments (0-1 cm) sampled at eighty two geographically dispersed stations in the three subbasins of Lake Baikal. The species composition shows the highest contribution of planktonic diatoms, especially the endemic species of Aulacoseira baicalensis , Cyclotella minuta and Cyclotella baicalensis , in pelagic regions. The contribution of pennate benthic algae that are delivered by the Selenga and live near the delta is restricted to shallow waters along the shore. Aulacoseira baicalensis amount to 87% of the diatom and cyst total in northern North Baikal and to 60% in Central Baikal. Spores of Aulacoseira skvortzowii have rather high percentages in the Selenga delta region (about 30%) and in South Baikal (up to 20%) but are within 5% in the Northern and Central subbasins. Thick-wall frustules of Aulacoseira baicalensis reach the highest weight percent, up to 0.4 g per 1 g of dry sediment. The density of diatoms simulated in a 3D model on the basis of mean sedimentation rates and mean cell sizes correlates with mean annual particle fluxes to the three Baikal subbasins and the Selenga delta region.
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