Acta Biologica Sibirica 11: 937–967 (2025)
RESEARCH ARTICLE
Influence of tributaries on the species richness
of silica-scaled chrysophytes in the Angara River
(Russia, Eastern Siberia)
Anna Y. Bessudova1, Alena D. Firsova1, Yuri P. Galachyants1, Darya P. Petrova1, Maria A. Nalimova1, Maria V. Sakirko1, Yelena V. Likhoshway1
1 Limnological Institute, Siberian Branch of the Russian Academy of Sciences, 3 Ulan-Batorskaya st., Irkutsk, 664033, Russia
Corresponding author: Alena D. Firsova (adfir71@yandex.ru) Academic editor: R. Yakovlev | Received 3 July 2025 | Accepted 1 August 2025 | Published 19 September 2025
http://zoobank.org/51390B37-9789-405D-892C-37C6B52A9474
Citation: Bessudova AY, Firsova AD, Galachyants YuP, Petrova DP, Nalimova MA, Sakirko MV, Likhoshway YeV
(2025) Influence of tributaries on the species richness of silica-scaled chrysophytes in the Angara River (Russia, Eastern Siberia). Acta Biologica Sibirica 11: 937–967. https://doi.org/10.5281/zenodo.17132371
Abstract
The escalating impact of climate change requires comprehensive monitoring of aquatic microeukaryotic communities. Specifical y, it is essential to study their successional dynamics under natural thermal fluctuations and identify organisms particularly sensitive to these changes. During the hydrological spring (early June), the watercourses of the Angara region differ in the intensity of water warming and can serve as promising model systems for studying such variations. Chrysophytes, which form siliceous scaled shel s, serve as indicators of water temperature changes. In this study, we analyzed the influence of the main tributaries in the upper reaches of the Angara River–Irkut, Kuda, Kitoy, Belaya, and Ida–on the species richness of silica-scaled chrysophytes in the river channel, which is mainly affected by the cold, oligotrophic waters of Lake Baikal. During research performed in June 2024, a total of 57 silica-scaled chrysophytes species were identified in the study area using scanning and transmission electron microscopy. Among these, 11 species are potential y new to science, while one rare species Paraphysomonas capreolata and the form Synura peterseni f. columnata were recorded for the first time in Russian water bodies. The analysis demonstrated a positive correlation between the species diversity of silica-scaled chrysophytes and both water temperature and silicon concentration, alongside a negative correlation with pH levels. Statistical analysis of silica-scaled chrysophytes occurrence revealed two main profile groups: those from the main channel of the Angara River and those from its tributaries. Thus, it was determined that tributaries considerably increase the species richness of silica-scaled chrysophytes communities in the large river system, thereby increasing the Copyright Anna Y. Bessudova et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC
BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
938 Anna Y. Bessudova et al. / Acta Biologica Sibirica 11: 937–967 (2025) overall stability of the aquatic ecosystem. This research is important for understanding the underlying mechanisms of the formation of biodiversity in freshwater ecosystems.
Keywords
Chrysophyceae, tributaries, Baikal Region, environmental factors