Vol 17, No 4 (2024)

By using mathematical modeling methods, a systematic study of the interaction of hydrobiological, hydrochemical, hydrological and hydrophysical processes that occur in the ecosystem of the Vistula Lagoon (VL) of the Baltic Sea was carried out, taking into account the processes in the active layer of bottom sediments (BS). The features of the dynamics of nitrogen and phosphorus compounds, the turnover time and the components of the balance of compounds of biogenic elements in the VL ecosystem, as well as the degree of their temporal variability have been analyzed. It is shown that the variability of nitrogen and phosphorus compounds in the aquatic environment increases in spring and autumn periods. This is due to an increase in river flow into the lagoon and an increase in the level of external biogenic load on the water area of the VL. Model calculations of matter fluxes allow us to state that the inputs of dissolved organic and suspended matter into the lagoon from external sources and the removal to the Baltic Sea are important processes that significantly affect their content in the VL ecosystem. It has been established that under strong winds the process of sedimentation of suspensions can be largely blocked, and the intensity of BS resuspension can increase significantly. An analysis of the main qualitative and quantitative features of the nature of the temporal dynamics of the DON and DOP turnover times, as well as the mineral compounds of nitrogen and phosphorus, indicates a close conjugation of the processes of transformation of dissolved organic and inorganic substances in the water of the VL. A quantitative assessment of the processes of consumption and excretion of compounds of biogenic elements by different groups of aquatic organisms has been performed, and the important role of heterotrophic bacterioplankton and protozoa in the processes of transformation of compounds of nutrients in the VL ecosystem has been shown. The model can be used to perform scenario modeling and analysis of possible changes in the VL ecosystem under changing climatic and anthropogenic conditions.

On own material and on the basis of literary data, a synthesis of information on the genus Tobrilus Andrássy, 1959. The diagnosis this genus has been changed; species diagnostic characteristics have been analyzed; the species structure of the genus has been examined. The genus includes 29 valid species. The key to the definition of species of genus and the summary table of morphological characteristics of valid species are given.

The composition and nature of changes in the low-molecular-weight metabolome (NM) of Potamogeton perfoliatus L., growing in 6 biotopes of Lake Ladoga with different types of the anthropogenic load has been analyzed. According to the research results, it was found that the total number of low molecular weight organic compounds (LMWOCs) in the P. perfoliatus NM composition is directly dependent on anthropogenic load, which is well marked by the development of cyanobacteria. The greater the intensity of pollution or eutrophication of waters, or the higher the number of cyanobacteria, the lower the total number of LMWOCs and their concentration. A strongly pronounced dependence of the total concentrations of groups of NM compounds on the anthropogenic disturbance of the biotope and the concentration of cyanobacteria was revealed. A decrease in the number, relative amount, total concentration of carboxylic acids, number and content of unsaturated fatty acids, and, at the same time, an increase in the composition and content of phenols and the total content of aldehydes and ketones depends on an increase in anthropogenic pressure. The specific composition of NM of pierced pondweed depends on its response to biotic and abiotic factors of the aquatic environment, including anthropogenic ones. The revealed features of the change in the composition of P. perfoliatus NM make it possible to use it as an integral indicator of the anthropogenic impact on the littoral biotopes of water bodies and the deterioration of their ecological state.

In cells of a culture of the large diatom Ditylum brightwellii (T. West) Grunow acclimated to weak light (17 μmol photons/(m² × s)), numerous chloroplasts were evenly distributed throughout the cell cytoplasm. After 10 min of exposure of algae to extremely high illumination (1100 μmol photons/(m² × s)), their aggregates gradually formed in the center of the cell, which continued until the end of the two-hour exposure period. At light intensities of 510–935 µmol/(photons/(m² × s) during short-term photoacclimation, chloroplast aggregation was noted for 20–60 min, after which their reverse movement and uniform distribution in the cytoplasm were revealed by the end of the second hour. Under conditions of a longer culture stay at a light intensity of 1100 μmol photons/(m² × s), the algae retained their viability for only six hours. Long-term photoacclimation of this species, which ended by the end of the second day, was detected when the light weakened by about 2 times. It was expressed as an increase in cell volume and C/Chl a ratio, increased aggregation of chloroplasts in the center of the cell, and a decrease in a number of fluorescent parameters reflecting the efficiency of photosystem II and culture viability.

The article presents the results of a comprehensive study of two components of the aquatic biocenosis: its floristic component and benthos in the shallow waters of the Gorky reservoir within the water area of the Yaroslavsky nature reserve. The composition and structure of plant communities at the boundary of the macrophyte belt was assessed, followed by the identification of dominant associations. In parallel, the taxonomic composition and quantitative characteristics of macrozoobenthos were assessed in the main plant biotopes. Plant communities in the water area are represented by two ecological groups: helophytes and hydrophytes. Macrophytes occupy up to 25% of the water area of the shallow area of the studied water body. Most of the plant communities are concentrated in the northern and northeastern parts of the reserve. 11 species of macrophytes belonging to 10 genera and 9 families were noted. In macrophyte communities, 8 typical associations were identified, where benthos sampling was carried out. In the benthos of typical macrophyte associations, 35 lower definable taxa (LTOs) were identified, of which 17 LUTs are chironomid larvae. In the biotope, 11 HOTs were found out of vegetation. The highest species richness of benthic invertebrates was noted in the communities of Butomus umbellatus L. (1753) and Sparganium erectum L. The benthos of plant communities in August 2021 can be characterized as chironomid-oligochaete, while chironomids dominated in the open littoral. Mollusks played a significant role in the formation of benthos in plant communities. The maximum quantitative indicators of benthic invertebrates in general and the abundance of chironomids of the river. Glyptotendipes in particular have been noted in the community of the burr Sparganium erectum. This is probably due to the morphological structure of this plant and the specifics of the formation of the community by this species. The benthos of plant communities was dominated by phytodetritophages–filterers and phytodetritophages–filterers + gatherers, while in the open littoral, phytodetritophages–filterers prevailed. In all studied biotopes, there were no detritophages–gatherers. In general, according to the abundance of macrozoobenthos, the areas of plant communities can be classified as high-nutrient and very high-nutrient.

As a result of global warming, the average annual water temperature has significantly increased in the Upper Volga reservoirs. Warming and the subsequent deterioration of the oxygen regime had a significant effect on most of the fish populations inhabiting temperate waters. This led to changes in the population structure of many fish species. Such phenomena as the disappearance or a sharp decline in the abundance of cold-water species (European smelt, vendace, burbot and pike) in the Rybinsk reservoir coincided with the period of warming. The disappearance of European smelt in the Rybinsk Reservoir and the favorable temperature regime contributed to the appearance and rapid increase in the abundance of the Caspian invader, the Black Sea sprat, which occupied the empty niche of the European smelt and became instead the dominant species in the pelagic zone of the Upper Volga reservoirs. Warming resulted in a decrease in the abundance and the growth rate of burbot and pike. Climate warming had an indirect effect on many species through oxygen deficiency or transformation of the forage base (ruff, zander, perch, roach), which also led to a decrease in abundance and the growth rate.

The article presents data on polymorphism of intermicrosatellite sequences in the sterlet Acipenser ruthenus of the lower reaches of the Irtysh River and the middle reaches of the Ob River. We assessed intra- and interpopulation variability and genetic differentiation of A. ruthenus and revealed a high ISSR polymorphism in the species from the central part of the Ob-Irtysh basin. The proportion of polymorphic amplicons was 0.966, genetic diversity was 0.355, and the average number of alleles per locus was 1.97. The highest polymorphism was typical for the sterlet from the Tobol River at the confluence with the Irtysh River. Genetic differentiation between the sterlet groups of the Irtysh and Ob rivers is well pronounced, the interpopulation component accounts for 42% of variability (Gst = 0.42), gene flow is limited (Nm = 0.67). The sterlet groups inhabiting the Lower Irtysh from the mouth of the Tobol River to the mouth of the Konda River do not differ genetically and form one population (Gst = 0.08–0.12, Nm = 3.76–5.55). The sterlet from the Irtysh River within the Vagay region is genetically different from the other Irtysh samples (Gst = 0.22, Nm = 1.68) and belongs to a different population group. The differentiation between samples of sterlet from the Ob basin is higher than between samples from the Irtysh basin. Groups of sterlet from the Ob River and the Yuganskaya Ob canal are genetically different (Gst = 0.30, Nm = 1.19) and form various subpopulations. Spawning migrations, as well as confinement to wintering pits, play a decisive role in the formation of the sterlet population structure in the studied part of the distribution area. The identified sterlet population groups should be considered as separate units of environmental and economic management.

The dynamics of capture of 4 Sturgeon species (family Acipenseridae): Russian sturgeon Acipenser gueldenstaedtii, Sterlet A. ruthenus, Stellate Sturgeon A. stellatus, Beluga Acipenser (Huso huso) in the IUU catches of the Ural (Zhaiyk) River within of the Republic of Kazakhstan borders is done. The annual number of Sturgeons estimated by arrested IUU catches in the period 2012–2018 which demonstrate the fluctuation of the Ural River Sturgeons number as well as male dominance is given. The biological indicators of Ural’s Sturgeons during the period of maximum catches in 2018: sex ratio, age, weight, length, length-weight relationship are given.

Under experimental conditions, the larval development of a fish parasite, Acanthocephalus tenuirostris was studied. This species is common in the eastern regions of Russia from Primorye Territory to the upper reaches of the Kolyma River. The material for the experiments was collected in different areas of the Magadan region which is located mainly in the subarctic climate zone. In several series of experiments, the infection and maintenance of intermediate hosts, the isopod Asellus hilgendorfii, took place at a constant temperature 15°C. In all cases, no more than 45 days were required for the formation of the final cystacanth stage. At the same time, in the hemocoel of isopods a large number of other larval stages were present simultaneously with cystacants. An additional experiment was conducted for the first 45 days at 15°C and the next 207 days at 4–6°C, showed the possibility of further development of larvae at low temperatures. Based on the comparison with the data available in the literature on the development times of European Acanthocephalus species living in temperate climates, it is concluded that the A. tenuirostris has anadaptation to a cold climate, whichprovides a twofold acceleration of the rate ofits development relative to larval A. lucii in Europe.

The presence of a complex of biologically active steroid compounds (BASC) – hydrocortisone, corticosterone, progesterone, testosterone and estrogens (vertebrate hormones) in invertebrate hydrobionts of different phylogenetic levels was revealed in the experiments. The features of the quantitative content of BASC in different organs/tissues of hydrobionts and their changes at different stages of development are shown. The level of BASC in organisms or their organs is largely due to their own steroidogenesis, but at the same time, organisms can accumulate exogenous steroid compounds. The adaptive role of ALS in some invertebrates in changing conditions of the aquatic environment has been found. The similarity of the concentration of steroid compounds in different groups of bionts leads to the idea of a certain “physiological constant” of this complex of compounds in all organisms.

The results of an experiment on oral exposure of polychlorinated biphenyl (PCB) 118 into fish Danio rerio (Hamilton, 1822) (F0) with food at calculated doses of 5, 20, 80 μg/ind. are presented. In the first generation F1, there is a decrease in survival rate and a shift in the sex ratio, predominantly towards females. In the second generation F2, the same effects are noted as in F1, but they are not as pronounced. It has been hypothesized that the effects seen in the F2 generation may be caused by epigenetic mechanisms, which are still poorly understood. It is possible that the feminization of animal populations and a decrease in their survival rate are very strong factors in reducing the populations of living organisms, including humans, especially near sites of distribution of PCBs. It is necessary to study epigenetic mechanisms in order to develop measures to eliminate and prevent problems with the biotic degradation and depopulation of fish exposed to PCBs in the sites that arise as a result of the improper disposal of electrical engineering waste containing PCBs.

The low molecular weight metabolome (LMWM) of Lobelia dortmanna L. (Campanulaceae, Magnoliophyta), a relic aquatic macrophyte listed in the Red Data Books of the Russian Federation and Republic of Belarus, was studied for the first time using the GC/MS technique. It is a macrophyte that grows in oligotrophic lakes in the northwest of the Vologda Region, Russia. Thirteen major chemicals were among the 127 volatile low molecular weight organic compounds (VOCs) discovered, which accounted for 77.23% of the overall VOC content (198.75 µg/g dry plant weight). The main components of LMWM were carboxylic acids and hydrocarbons. The presence of a large number of biologically active metabolites with a high concentration in L. dortmanna LMWM may indicate a significant effect of this plant on the hydrobiocenoses of the littoral zone of oligotrophic lakes. Further research into the LMWM of aquatic macrophytes in oligotrophic lakes, a valuable renewable resource, is needed to assess the background characteristics of the natural environment for more effective monitoring of the ecological state of water bodies in the Russian Federation's North-West and the rational use of their biological resources.