Diatom complexes in the bottom sediments of big Miassovo lake (South Ural, Russia)

Abstract

© SGEM 2019. The diatom method is a useful tool for reconstructing the history of lakes and for understanding the nature of changes in their water level that occurred in the past. It also shows the periods of freshwater and brackish phases in the development of water basins. A long core was taken in the deepest part of Lake Big Miassovo in July 2018. The core covered the time span of 13 500 years. Following the analysis of 14 core samples from Lake Big Miassovo, 97 diatom taxa belonging to 44 genera were identified. The dominance of cosmopolitan, alkaliphilic benthic, and oligogalobic species with the growth under moderate temperatures was revealed. The results of the diatom analysis demonstrated that the lake passed through three main periods in its development. The first period is the stage when the lake had a low water level. The increased number of Ellerbeckia arenaria specimens during that time shows that the near-stream vegetation was well-developed, probably with occasional moss species. The second period is characterized by the higher abundance of species that preferred acidic conditions, which can indicate that there were water-logged areas in the studied territory. The mass development of benthic diatoms was recorded in the upper part of the core, thereby demonstrating sufficient water transparency and depth values ranging within the middle ones.