Year-Round Presence of Microcystins and Toxin-Producing Microcystis in the Water Column and Ice Cover of a Eutrophic Lake Located in the Continuous Permafrost Zone (Yakutia, Russia).

This study aimed to test the hypothesis of the year-round presence of toxigenic Microcystis and cyanotoxins in the water and ice of the shallow eutrophic Lake Ytyk-Kyuyol located in the continuous permafrost zone. Three independent approaches-mass-spectrometry, molecular methods and light microscopy-were applied in the study. The cyanobacterial biomass ranged from 1.0 × 10-4 to 4.8 mg L-1. Microcystis flos-aquae and M. aeruginosa were the dominant morphospecies in plankton throughout the observation. In environmental DNA, the presence of M. aeruginosa was supported and mcy gene regions responsible for microcystin biosynthesis were detected through a BLAST (Basic Local Alignment Search Tool) search and phylogenetic estimation based on newly obtained 16S rRNA, 16S-23S ITS rRNA, mcyA and mcyE nucleotide sequences. The intracellular microcystin concentration ranged from <0.1 to 803 ng L-1, and the microcystin quota in the Microcystis biomass was extremely low. For the first time, it was shown that Microcystis cells containing mcy genes and microcystins presented permanently in the water column, both during the ice-free period and under ice, as well as inside thick ice covers within 7 months of severe winter. We hypothesized that minor pelagic and ice populations of Microcystis could participate in increasing cell density in the spring. However, further studies are needed to confirm the viability of the overwintering Microcystis colonies in the water and inside the ice of Lake Ytyk-Kyuyol.

Intra- to extracellular crystallization of calcite in the freshwater green algae Phacotus lenticularis.

Phacotus lenticularis is a freshwater unicellular green alga that forms lens-shaped calcitic shells around the cell. We documented P. lenticularis biomineralization pathways in live daughter cells while still within the reproductive complex, using scanning confocal microscopy and after vitrification using cryo-scanning electron microscopy (cryo-SEM). We show that some or all of the calcium ions required for mineral formation enter the cell through endocytosis, as inferred from the uptake of calcein fluorescent dye. Ions first concentrate inside intracellular vesicles to form small crystals that were detected by birefringence, reflectance, and cryo-SEM of cells in near-native, hydrated state. The crystals later exit the cell and build up the lens-shaped shell. The small crystals first cover the outer lorica surface and later fuse to form a thin continuous shell. This is most likely followed by a second shell maturation phase in which the shell undergoes thickening and crystal reorganization. Crystal assembly within the confined protected volume of the reproduction complex allows controlled shell formation outside the daughter cell. Only two other unicellular marine calcifiers, coccolithophores and miliolid foraminifera, are known to perform intracellular crystal formation. STATEMENT OF SIGNIFICANCE: Calcium carbonate (CaCO3) deposition in aquatic environments is a major component of the global carbon cycle, which determines the CO2 content of the atmosphere. In freshwater ecosystems, the green alga Phacotus lenticularis is considered the main contributor of autochthonous calcite precipitation and the only algal species known to form its shell through a controlled process. The chemical and ecological effects of P. lenticularis are intensively investigated, but our understanding of its shell formation is limited. We used advanced confocal laser scanning microscopy and cryo-scanning electron microscopy (cryo-SEM) to provide new insights into mineral formation and trafficking in the calcifying P. lenticularis cells.

Charophytes (Charophyceae, Charales) of South Kazakhstan: Diversity, Distribution, and Tentative Red List.

The presented research was conducted during 2019-2022 in south and southeast Kazakhstan to document the species richness, distribution, and ecology of charophytes (Characeae) as a first step towards to estimate the need for species protection. Across the 54 sites, we found ten species and one variety. Chara vulgaris Linnaeus and C. contraria A.Braun ex Kützing were the most common species, followed by C. canescens Loiseleur, C. kirghisorum C. F. Lessing, C. tomentosa Linnaeus, C. dominii J. Vilhelm, C. globata W. Migula, Nitellopsis obtusa (Desvaux) J. Groves, and Nitella hyalina (De Candolle) C. Agardh. The list of localities for each species was compiled. The distribution of each taxon was mapped in relations to the ecoregions studied. The two most frequent species were found in a wide spectrum of ecoregions, whereas all other species occurred in only a few regions in Kazakhstan. The Kaskelen River Valley had the most sampled sites with the highest number of co-occurring species (up to five together). Statistical maps were plotted in attempt to outline key environmental variables explaining the distribution of each species. A comparison of species and environmental variables distribution maps lets us assume that C. vulgaris prefers low altitude habitats with higher water temperatures, organic enrichments, and color, but low oxygen and pH. Other species prefer clear, alkaline, organically unpolluted, and well-oxygenated waters in lowland habitats. The redundancy detrended analysis (RDA) defined pH and altitude as negative factors for Nitellopsis obtusa whereas an increase in water temperature was positive. Altitude and water temperatures affected Chara contraria positively while altitude negatively influenced the rare species: Chara tomentosa, C. kirghisorum, and C. dominii. The matK sequences were obtained for C. contraria and C. vulgaris to confirm their identity according to morphological traits and to compare populations of C. gymnophylla and C. vulgaris from an arid region in Israel. Our data allowed for the preparation of a tentative red list from the study region. One species was recognized as endangered, four species and one variety as vulnerable, and two species as least concern. There was insufficient data to determine the status of two species and one variety.

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

For the first time, we investigated species composition, phytoplankton community structure, and hydrochemical parameters in the artificial cooling reservoir of a major thermal power plant (TPP) in northeastern Europe located in the Pechora River basin (Komi Republic). Our research, conducted during June and August, revealed a total of 81 species of algae and cyanobacteria, with cyanobacteria predominating. Among these cyanobacteria and microalgae (Bacillariophyta and Chlorophyta), algae that serve as reliable indicators of water quality were identified. The assessment of water quality based on abundance and species composition of indicator phytoplankton species revealed that the waters of the Pechorskoe Reservoir belong to the III class (ß-mesosaprobic or moderately polluted). This indicates that water quality is satisfactory, and the reservoir retains the ability to self-purify. The power plant's discharges heat the surface layers, increasing plankton communities' diversity, abundance, and biomass. Such stable warming in the upper layers throughout the season, uncommon for natural water bodies in the north, results in a slight increase in the trophic status of the studied reservoir, supported by hydrochemical analysis. These results provide valuable information about ecosystem functioning under temperature increasing for predicting changes in the phototrophic biota of small northern reservoirs facing the impacts of climate change.

Freshwater as a Sustainable Resource and Generator of Secondary Resources in the 21st Century: Stressors, Threats, Risks, Management and Protection Strategies, and Conservation Approaches.

This paper is a synthetic overview of some of the threats, risks, and integrated water management elements in freshwater ecosystems. The paper provides some discussion of human needs and water conservation issues related to freshwater systems: (1) introduction and background; (2) water basics and natural cycles; (3) freshwater roles in human cultures and civilizations; (4) water as a biosphere cornerstone; (5) climate as a hydrospheric 'game changer' from the perspective of freshwater; (6) human-induced stressors' effects on freshwater ecosystem changes (pollution, habitat fragmentation, etc.); (7) freshwater ecosystems' biological resources in the context of unsustainable exploitation/overexploitation; (8) invasive species, parasites, and diseases in freshwater systems; (9) freshwater ecosystems' vegetation; (10) the relationship between human warfare and water. All of these issues and more create an extremely complex matrix of stressors that plays a driving role in changing freshwater ecosystems both qualitatively and quantitatively, as well as their capacity to offer sustainable products and services to human societies. Only internationally integrated policies, strategies, assessment, monitoring, management, protection, and conservation initiatives can diminish and hopefully stop the long-term deterioration of Earth's freshwater resources and their associated secondary resources.

Remote sensing and in-situ approach for investigation of pelagic communities in the reservoirs of the electrical power complex.

BACKGROUND: Two closely located reservoirs on the Southern Bug River and its tributary in the southern region of Ukraine were compared to study the impact of temperature on hydrobionts and pelagic communities, a major ecologic issue in the climate warming context, using in-situ and satellite remote sensing data. These reservoirs are parts of the South-Ukraine electric power-producing complex. The Tashlyk reservoir is a cooling reservoir for the nuclear power plant, and Oleksandrivske reservoir is used for production of hydroelectricity and irrigation. The cooling reservoir is replenished by pumping water from the upper part of the Oleksandrivske reservoir. METHODS: The relationships of temperature, transparency, and distribution of phytoplankton and zooplankton communities were established based on satellite remote sensing data and in-situ during 2013-2021. The main variables of phytoplankton and zooplankton were compared, and for improved understanding features, spatial distribution maps were created. RESULTS: It was found that the distribution of coenotic groups of phytoplankton and zoonplankton in the cooling reservoir (Tashlyk) corresponds to thermal conditions. Three communities of phytoplankton and two communities of zooplankton were identified in the Tashlyk reservoir. However, in the Oleksandrivske reservoir, separate communities of phytoplankton and zooplankton were reported along its length. CONCLUSIONS: It was shown that both on land and in the Oleksandrivske reservoir, there is an increase in temperature in summer, an increasing trend in the global warming context, but that was not observed in the cooling reservoir of the nuclear power plant (NPP). It let us assume that the factors such as temperature or nutrients impact can be assessed as external significant factors related to the catchment area for the reservoirs with different types of using.

Assessment of water quality condition and spatiotemporal patterns in selected wetlands of Punjab, India.

Wetlands are one of the most productive aquatic ecosystems on earth, and their water quality is an indicative of their suitability for maintaining various ecosystem services. In this study, different statistical techniques and water quality index (WQI) were employed to access the status and spatiotemporal patterns in water quality of seven selected (two natural and five manmade) wetlands of Punjab. The results revealed that the status of water quality in the selected wetlands was between good and poor during studied seasons (summer, monsoon, and winter) of year 2019. The principal component analysis identified three groups of wetlands with distinct water quality characteristics with spatial patterns: Kahnuwan Chhamb and Keshopur Miani having nearly similar values of pH, total dissolve salts, electrical conductivity, chemical oxygen demand, total alkalinity, bicarbonate and ammonium content; Ropar, Kanjli, and Harike having higher value of nutrients than the other wetlands; and Ranjit Sagar and Nangal with low value of measured water quality characteristics. Further, analysis of variance revealed that all analyzed water quality parameters showed temporal patterns in water quality except water pH, electrical conductivity, dissolved oxygen, biological oxygen demand, and phosphate content. This comparative study enhanced our knowledge about the spatiotemporal patterns in water quality and in the future will be helpful to the policymakers and concerned authorities for developing better water quality management strategies for these wetlands.