Taxonomic diversity of diatoms of the epilithon of Lake Itkul (Republic of Khakassia)

УДК 582.26:581.93(285.2)(571.513)

Abstract

The article presents data on the taxonomic composition of diatom algae of the epilithon of Lake Itkul (Republic of Khakassia) under the conditions of water level rise in recent years (2018-2023). We recorded the fact of movement of quagmires with Phragmites australis (Cav.) Trin. ex Steud. along the lake. They were detached from the waterlogged western shore of the lake and rooted on shallow areas of other shores. In this regard, the article discusses possible reasons for the emergence of new species that were not previously recorded in the lake. 95 species (96 species and intraspecific taxa) were identified in the epilithon of Lake Itkul in 2023. 25 species of diatoms were new for the lake. Most species in the epilithon (65.6 % of the total number of species and infraspecific taxa) were low-active and inactive (occurrence 0-20 %). Mastogloia lacustris was an especially active species with 100 % occurrence. The species Mastogloia lacustris, Meridion circulare, Achnanthidium minutissimum dominated in the epilithon of the lake in 2023. We compared the results of our studies with data from 2006-2009. On the one hand, the composition of the epilithon is characterized by relative constancy: there are coincidences in the head part of the spectrum of leading families, in the composition of leading genera, and part of the dominant and co-dominant species. On the other hand, there were some transformations in the family and genus spectra, previously inactive species became dominants, the number of halophobes increased among salinity indicator species, acidophiles and acidobionts appeared among the groups related to pH of the environment. These changes may have occurred due to rising water levels. Further observations on the composition of diatom complexes are required.