Phytocenosis biodiversity at various water levels in mesotrophic Lake Arakhley, Lake Baikal basin, Russia

Abstract

Small lakes have lower water levels during dry years as was the case in 2000–2020. We sought to show the biodiversity of plant communities at various water levels in Lake Arakhley. Changes in moisture content are reflected in the cyclical variations of the water level in the lake, which decreased approximately 2 m in 2017–2018. These variations affect the biological diversity of the aquatic ecosystems. We present the latest data on the state of the plant communities in this mesotrophic lake located in the drainage basin of Lake Baikal. Lake Arakhley is a freshwater lake with low mineral content and a sodium hydrocarbonate chemical composition. Changes in the nutrient concentration were related to precipitation; inflow volume and organic matter were autochtonous at low water levels. The most diverse groups of phytoplankton found in the lake were Bacillariophyta, Chlorophyta, and Chrysophyta. High biodiversity values indicate the complexity and richness of the lake’s phytoplankton community. A prevalence of Lindavia comta was observed when water levels were low and Asterionella formosa dominated in high-water years. The maximum growth depth of lacustrine vegetation decreased from 11.0 m to 4.0 m from 1967 to 2018. Decreasing water levels were accompanied by a reduction in the littoral zone, altering the communities of aquatic plants. The hydrophyte communities were monodominant in the dry years and were represented by Ceratophyllum demersum. The vegetation cover of the lake was more diverse in high-water years and variations in the lake’s water content altered the composition of biogenic substances. These changes were reflected in the lake’s phytocenosis.

Role of Lake Aquatic–Terrestrial Ecotones in the Ecological Restoration of Eutrophic Water Bodies

“…Changes in water level can lead to changes in redox conditions in lake ecotones, and they can also exert some stress on the growth of plants. Moreover, when there is a significant difference in the lake water level, there are significant differences in the soil microbial communities in vegetation buffer zones [ 84 , 85 , 86 ]. At high water levels (a high water level for a deep lake is 40–50 m, and a high water level for a shallow lake is 10–20 m), the soil redox potential is the main factor affecting the soil microbial community composition in the vegetated buffer zone.…”

Primary production and destruction of organic matter in Lake Arakhley (Eastern Transbaikalia, Russia)

“…The fluctuations of the water level in Lake Arakhley observed since 1956 are cyclical in nature [2]. The minimum level (BHS-1977) was recorded within the latest cycle dated from 1980 to 2017 [5], when the depth of the lake decreased by 2 m.…”

“…According to the observations, Lake Arakhley is defined as a mesotrophic water body. The investigations on the lake are currently continued by [5,[9][10][11][12][13].…”