Environmental Factors Affecting Distribution and Diversity of Phytoplankton in the Irkutsk Reservoir Ecosystem in June 2023

Abstract

Studying correlations between phytoplankton communities and environmental factors is critical for understanding how aquatic ecosystems function. The high sensitivity of phytoplankton to changes in these factors makes it possible to control the state of the ecosystem of water bodies. Artificial lakes often demonstrate increased trophic status, inducing changes in phytoplankton structure. In this paper, we studied phytoplankton in June 2023 (hydrological spring) in two ecosystems, South Baikal and the Irkutsk Reservoir, that are connected by a water course but have different environmental parameters. The gradient of environmental parameters from the lake towards the reservoir revealed peculiarities in the distribution of some microalgae species. Microscopy and statistical analysis showed that water temperature was the most important factor affecting the structure of the communities. The warmer water of the reservoir, in contrast to the lake, demonstrated a twofold increase in species number, abundance, and biomass. Downstream from the reservoir, we observed a succession in the dominating Baikal species complex, its supplementation, and replacement with other species typical of the summer period and Baikal bays. The trophic status of the reservoir during the study may be described as oligotrophic, with local traits of mesotrophicity; its water refers to Class I and Class II and may be qualified as clean.

Screening of Phytoplankton Dynamics: Assessing Reservoir Ecosystem Health under Thermal Pollution from an Electrical Power Plant in the Pechora River Basin, European North

“…The abundance and biomass of these phytoplankton organisms ranged from 2.3 to 7.7 million cells per liter and 0.39 to 2.36 milligrams per liter, respectively. Species composition and quantitative data are similar to those commonly observed in northern ecosystems of the study area [22,47] and northern water bodies of other regions [48].…”

“…The mass development of this species in northern water bodies, resulting in "blooming", is quite rare [54][55][56], but cyanobacteria blooming is known even in the permafrost zone water bodies [57]. Usually, at the beginning of the growing season, species from Bacillariophyta dominate the starting of the growing season of northern water bodies [47][48][49][50]. Diatoms are known to prefer colder water and are abundant in temperate lakes and reservoirs in autumn and spring when water temperatures are cooler [58].…”

Changes in Diversity of Silica-Scaled Chrysophytes during Lake–River–Reservoir Transition (Baikal–Angara–Irkutsk Reservoir)

“…This trend supports the claim that the species diversity of silica-scaled chrysophytes in oligotrophic waters is low and may consist of only a few species [11,45]. Nevertheless, in June, Irkutsk Reservoir was also oligotrophic (with some mesotrophic traits) [46] according to its hydrochemical parameters, but it had relatively high species diversity.…”

Rapid flotation of Microcystis wesenbergii mediated by high light exposure: implications for surface scum formation and cyanobacterial species succession

“…The dominant niche of high temperature-adapted cyanobacteria genera will be further reinforced with global warming and elevated carbon dioxide in the future. The cyanobacterial dominance and succession are inherently attributed to the distinctive traits of cyanobacteria including colony formation, gas vesicles, toxin release, and nitrogen fixation ( Wang et al., 2021 ; Firsova et al., 2023 ). In the future, we will further explore the extracellular substances released by Microcystis and the physiological and biochemical effects of Microcystis .…”