Species composition, taxonomic structure and dominant phytoplankton complexes of rivers and streams of the Krasnoyarsk Pillars National Park

The Krasnoyarsk Pillars National Park is located in the suburbs of Krasnoyarsk. The geographical coordinates of the park are 55°38'-55°58' N, 92°20'-93°20' E, the territory is part of the Altai-Sayan fold system. The territory of the national park is experiencing increased anthropogenic impact associated with high recreational load due to the location of the park. The study of biodiversity of special protection natural areas is currently very relevant; phytoplankton occupy a special place among the main components of aquatic ecosystems as a basic element in the formation of trophic status and water quality. Research on the phytoplankton of rivers and streams in the territory of the Krasnoyarsk Pillars National Park was not carried out until 2021. The purpose of this article is to characterize the species composition, taxonomic structure and dominant complexes of phytoplankton in the rivers and streams of the Krasnoyarsk Pillars National Park. The article uses materials from the processing of phytoplankton samples from rivers and streams of the Krasnoyarsk Pillars National Park, collected in August 2021-2023 (see Fig. 1). Selection, fixation and processing of samples were carried out using generally accepted methods. Diatom species were identified on permanent preparations and from images obtained on a JSM-6510LV scanning electron microscope (SEM). Species whose abundance was at least 10% of the total were classified as dominant. The choice of the abundance criterion is due to the greater metabolic activity of small organisms compared to large ones. Dominant complex analysis was performed using frequency of occurrence (pF), dominance frequency (DF), and dominance order (Dt). As a result of the research, 253 species and intraspecific taxa (SIT) of algae were identified, including the nomenclatural type of species, from 7 departments, including: Cyanoprokaryota - 8, Chrysophyta - 6, Dinophyta - 1, Euglenophyta - 12, Bacillari-ophyta - 188, Chlorophyta - 35, Charophyta - 3. The predominant importance in the taxonomic structure belongs to Bacillariophyta (74.31%), the share of other departments ranges from 1-14% (see Table 1). The taxonomic spectrum of phytoplankton demonstrates a clear predominance of diatoms at all levels: classes (Bacillari-ophyceae, 68.77% of the total number of SIT), orders (Cymbellales - 20.95%, Navicu-lales - 18.18%), families (1st to 6th place - 46.24%) and genera (from 1st to 6th place -30.83%) (see Table 2). The species composition and taxonomic structure of phytoplankton in rivers and streams of the Krasnoyarsk Pillars National Park have features typical of mountain streams. The dominant phytoplankton complex is diverse, it is formed by 22 SIT from 4 departments, including: Cyanoprokaryota - 3, Bacillari-ophyta - 6, Chlorophyta - 11, Chrysophyta - 2 (see Table 3). The dominants include 8.70% of the total number of SIT found in the water bodies of the National Park, they are dominated by species from the Chlorophyta department (50.0% of the total number of dominants). The maximum indicators of order and frequency of dominance are characteral of the cyanoprokaryote Aphanocapsa holsatica (DF = 68.72, Dt = 100), the second and third places in importance of these indicators are occupied by the diatoms Cocconeis euglypta (DF = 59.09, Dt = 68.42) and Meridion circulare (DF = 31.82, Dt = 77.80). The composition and structure of the dominant phytoplankton complexes vary significantly over the years of research; particular specificity is inherent in the dominant complex in 2021. The dominant phytoplankton complex of rivers and streams of the National Park is characterized by polydominance, significant interannual differences in composition and structure, dominance of heterocyst-free small-celled cyanoprokaryotes and random planktonic species of diatoms, a significant proportion of chlorococcal algae, including small-celled species, among the minor dominants. This indicates the presence of negative processes developing in aquatic ecosystems, which is undoubtedly associated with increased anthropogenic impact due to high recreational load. The current situation requires further biomonitoring of the water bodies of the Krasnoyarsk Pillars National Park and assessment of the level of recreational load on its territory. The article contains 1 Figure, 4 Tables, 57References. The Authors declare no conflict of interest.