Detailed results of diatom analysis of bottom sediments from lake Big Miassovo (Chelyabinsk region, Russia)

Diatoms are good indicators of a variety of lake water conditions including salinity, pH, light availability, temperature and nutrient levels, but diatoms as palaeoindicators are relatively poorly studied in the Chelyabinsk region. The diatom results of analysis a 498 cm long continuous sediments core from the Lake Big Miassovo (Southern Urals, Russia) are presented. The core was collected in July 2018 from central part of the lake from a depth of 24 m. Diatom analysis of 51 samples revealed 124 taxa, belonging to 47 genera. Diatom diagram has been divided into two diatom zones and five subzones on the basis on changing diatom abundances and taxa composition. The predominance of cosmopolitan, alkaliphilic benthic, oligogalobic species with the growth under the moderate temperatures is noted. The prevalence of Handmannia comta diatom in sediments have been established. The first period reflected the stage of an oligotrophic-mesotrophic lake with a low water level. The second period is characterized by an increase in the number of planktonic species and diversity of diatoms communities, the formation of a deep water body in a warm climate.