Planktonic Communities in the Torey Lakes (Zabaikalsky Krai) in a Low Water Year

Lakes Barun-Torey and Zun-Torey are the largest water bodies in Zabaikalsky Krai, and they are characterized by long-term cyclic changes in the water level. Samples of the planktonic community (algae and invertebrates) were collected from the Torey Lakes in June, August, and October in the dry 2016. Collection and processing of the samples was carried out using standard hydrobiological methods. The aim of the study was to investigate the planktonic communities in the Torey Lakes. The lakes were in different hydrological phases: Barun-Torey was in the initial filling phase (with isolated small lakes present on the dried bed), and Zun-Torey was in the shallowing phase. Considerable differences were observed between the compositions and structures of the planktonic communities, which were determined by the mineral content of the water. Diverse littoral plankton developed, consisting of 2-25 taxa of algae (total number of taxa – 46) and 2-15 species of invertebrates (total number of species – 29) in the oligohaline small lakes on the bottom of Lake Barun-Torey. The abundance and biomass of aquatic organisms varied within very wide limits: for phytoplankton – from 0.7 × 103 to 1260.0 × 103 cells / L and from 0.1 to 1271.0 mg / m3, and for zooplankton – from 9.2 × 103 to 19370.0 × 103 individuals / m3 and from 3.8 to 361.7 g / m3. Freshwater and euryhaline species were dominant. In polyhaline Lake Zun-Torey, the phytoplankton consisted of 3-12 taxa of algae (total number of taxa – 18), and the invertebrate fauna included only 3 species. The abundance of phytoplankton varied from 12.4 × 103 to 310.7 × 103 cells / L and a biomass from 1.0 to 14.7 mg / m3, and the abundance of zooplankton varied from 55.1 × 103 to 1656.0 × 103 individuals / m3 and a biomass from 1.1 to 85.5 g / m3. Euryhaline and halophilic species dominate

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

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

Plankton community and the relationship with the environment in saline lakes of Onon-Torey plain, Northeastern Mongolia

The plankton community of sixteen saline lakes located on Onon-Torey plain (Northeastern Mongolia) during the filling phase and the raising of the water level was investigated in July 2011. Thirty-five taxa of phytoplankton and thirty-one species of zooplankton were found. For phytoplankton, blue-green algae (Merismopedia elegans, Anabaenopsis elenkinii, Arthrospora fusiformis, Spirulina major, Lyngbya sp., Oscillatoria sp.) and green algae (Monoraphidium minutum, Tetrastrum komarekii, Ankyra ocellata, Oocystis sp.) were dominant. For zooplankton, Filinia longiseta, Brachionus plicatilis, B. variabilis, Hexarthra mira (Rotifera), Daphnia magna, Moina brachiata, M. mongolica (Cladocera), Arctodiaptomus bacillifer, Mixodiaptomus incrassatus, Metadiaptomus asiaticus (Copepoda) dominated. Mineralization, active hydrogen ratio, dissolved oxygen and water temperature were the main factors influencing the diversity, structure and distribution of plankton organisms in the steppe lakes during low water level. The RDA analysis for phytoplankton and zooplankton from different lakes was carried out for selected two groups which included lakes and a subset related species. The first group is of oligohaline and mesohaline lakes in which mostly green algae, rotifers and copepods inhabit. The second group is of mesohaline and polyhaline lakes with mainly blue-green algae, some crustaceans and rotifers inhabiting. High abundance and biomass of Spirulina major, Oscillatoria sp. and Brachionus variabilis were observed in lakes with high mineralization, pH and temperature

Особенности планктонных сообществ Торейских озер (Забайкальский край) в маловодный год

Lakes Barun-Torey and Zun-Torey are the largest water bodies in Zabaikalsky Krai, and they are characterized by long-term cyclic changes in the water level. Samples of the planktonic community (algae and invertebrates) were collected from the Torey Lakes in June, August, and October in the dry 2016. Collection and processing of the samples was carried out using standard hydrobiological methods. The aim of the study was to investigate the planktonic communities in the Torey Lakes. The lakes were in different hydrological phases: Barun-Torey was in the initial filling phase (with isolated small lakes present on the dried bed), and Zun-Torey was in the shallowing phase. Considerable differences were observed between the compositions and structures of the planktonic communities, which were determined by the mineral content of the water. Diverse littoral plankton developed, consisting of 2-25 taxa of algae (total number of taxa – 46) and 2-15 species of invertebrates (total number of species – 29) in the oligohaline small lakes on the bottom of Lake Barun-Torey. The abundance and biomass of aquatic organisms varied within very wide limits: for phytoplankton – from 0.7 × 103 to 1260.0 × 103 cells / L and from 0.1 to 1271.0 mg / m3, and for zooplankton – from 9.2 × 103 to 19370.0 × 103 individuals / m3 and from 3.8 to 361.7 g / m3. Freshwater and euryhaline species were dominant. In polyhaline Lake Zun-Torey, the phytoplankton consisted of 3-12 taxa of algae (total number of taxa – 18), and the invertebrate fauna included only 3 species. The abundance of phytoplankton varied from 12.4 × 103 to 310.7 × 103 cells / L and a biomass from 1.0 to 14.7 mg / m3, and the abundance of zooplankton varied from 55.1 × 103 to 1656.0 × 103 individuals / m3 and a biomass from 1.1 to 85.5 g / m3. Euryhaline and halophilic species dominatedОзера Барун-Торей и Зун-Торей являются самыми крупными водоемами в Забайкальском крае, для них характерна хорошо выраженная цикличность, проявляющаяся в многолетних изменениях уровня воды. Материалом для работы послужили пробы, собранные на Торейских озерах в июне, августе, октябре в маловодный 2016 г. Сбор и обработка материалов проводилась согласно стандартным гидробиологическим методам. Целью работы стало изучение особенностей развития планктонных биоценозов Торейских озер, одновременно находящихся в разных гидрологических фазах: Барун-Торей – в начальной фазе наполнения, Зун-Торей – в фазе снижения уровня воды. В районе северной оконечности высохшего Барун-Торея в пределах дна его ложа отмечались мелкие водоемы, источником питания которых служила многолетняя мерзлота и разгрузка подземных вод по разлому, проходящему по западному берегу озера. В Зун-Торее продолжался процесс обмеления водоема, который закончился практически полным его высыханием осенью 2017 г. Состав и структура фитопланктона и зоопланктона в разные гидрологические периоды имели существенные различия, определяемые уровнем минерализации озерных вод. В олигогалинных водоемах котловины Барун-Торея развивался литоральный планктоценоз, состоящий из 46 таксонов водорослей (при колебаниях от 2 до 25) и 29 видов беспозвоночных (при колебаниях от 2 до 15). Значения численности и биомассы гидробионтов колебались в очень широких пределах: фитопланктон – от 0,7 до 1260,0 тыс. кл/л и от 0,1 до 1271,0 мг/м3, зоопланктон – от 9,2 до 19370,0 тыс. экз/м3 и от 3,8 до 361,7 г/м3. Доминировали пресноводные и эвригалинные виды. Альгофлора полигалинного оз. Зун-Торей состояла из 18 таксонов (при варьировании от 3 до 12), фауна беспозвоночных – из 3 видов. Количественные показатели варьировали от 12,4 до 310,7 тыс. кл/л и от 1,0 до 14,7 мг/м3 для фитопланктона, и от 55,1 до 1656,0 тыс. экз/м3 и от 1,1 до 85,5 г/м3 – для зоопланктона. Преобладали эвригалинные и галофильные вид