Volume 18, Nº 3 (2025)

The work is devoted to the dynamics of the vegetation cover of mires formed in lake basins of the southwestern part of Western Siberia having a limnogenic stage in their development. Based on the analysis of two stratigraphic sections made on peat bogs of the Tyumen Region, the role and diversity of macrophytes of the lake stage is shown, and the further development of mires as a result of peat accumulation is described. Comparison of data on the composition of lake paleovegetation from sapropel deposits with modern vegetation of primary mire lakes in the study area showed their significant similarity in species composition.

The biomorphological features of Scolochloa festucacea (Willd.) Link in the central part of European Russia have been studied; the modular and structural-functional organization of the shoot system has been considered and the life form has been clarified. It was found that S. festucacea is characterized by the resumption of a mixed type (a combination of intra- and extravaginal types) and a combination of silleptic and cataleptic types of branching. The presence of an extravagant type of branching is manifested in the potential for the formation of partial bushes, the presence of which contributes to a stronger fixation of the plant in space. The combination of two types of branching leads to heterochrony, the development of buds at different times. The possibility of shoots lies down, their further rooting in nodes and the subsequent development of axillary buds into orthotropic shoots has been shown, which contributes to the correction of the spatial structure of the clone, the growth of its total assimilating surface and a potential increase in reproductive function. A comparative analysis of the modular organization of S. festucacea has shown its similarity in the number and types of elementary modules with those of long-rhizome sympodial the growth of long-shoot helophytes. The analysis of the structural and functional organization of S. festucacea monocarpic shoots revealed the presence of three variants differing in a set of structural and functional zones.

The material for the study of fungi from the bottom sediments of the Black Sea was collected on the voyages of the NIS “Professor Vodianitsky” (2013, 2016, 2017) at 64 stations in the depth range of 18–2080 m. Mushrooms were isolated by the culture method. 42 species of terrigenous fungi have been identified, the most represented families are Aspergillaceae and Pleosporaceae – 52.4% of the total number of species (17 and 5 species, respectively). A low abundance and frequency of occurrence of all species was recorded, Stachybotrys chartarum was most often noted (29.7%). 1–16 taxa were isolated from the samples for nutrient media, the number varied from 12–25363 (on average 2579 ± 4882) CFU/g of dry soil. The species composition and structure of mycocomplexes of sediments of various depths and different granulometric composition have been revealed. The highest indicators of species richness and abundance were recorded at depths of <100 m and in muddy sediments. The preservation of the viability of fungi in the sediments of the hydrogen sulfide zone has been confirmed. The influence of sediment depth, temperature, and salinity on the structure of mycocomplexes has not been established.

This review is devoted to cyanobacterial metabolites with allelopathic activity. The allelopathic properties of cyanobacteria have been studied relatively recently, and many aspects of this problem remain controversial. The chemical structure of allelochemicals produced by cyanobacteria is diverse (alkaloids, phenolic compounds, organic acids, cyclic peptides, fatty acids, etc.), and the spectrum of biological action is extremely wide and covers almost all aquatic inhabitants. Allelopathy is considered a strategy for regulating phytoplankton communities, helping to maintain species diversity in aquatic ecosystems. Cyanotoxins, including microcystins, exhibit high allelopathic activity towards aquatic organisms. In addition to the effect of cyanobacterial allelochemicals on phytoplankton, they exhibit antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory and antitumor activity, which indicates their potential for application in agriculture and pharmacology. The ecological role of allelochemicals, the mechanisms of action, and the influence of environmental factors are discussed.

The analysis of materials of researches conducted by E.R. Trufanova in 1966–1969 on aquatic vascular plants of water bodies of the lower reaches of the Kolyma River, original data collected in 2015 and 2020, and multi-temporal satellite images showed a number of changes in the vegetation cover of water bodies. Seven species previously reported for the studied lakes were not found and 10 taxa not recorded or not recognized were found. A scheme for identification the successional stage of water bodies is proposed. Most of the studied water bodies are in the “old” stage. The greatest diversity of aquatic plants is characteristic for the stage “mature lakes” and “old lakes with a single water area”. The example of Zhirkovo 1 Lake showed that for >50 years it has remained at the same stage of development, but the species composition has changed significantly (K_J = 0.41). While maintaining the current trends of climate change (increase in average annual temperature and precipitation), the studied water bodies will continue unidirectional aging and overgrowing, which will be accompanied by a decrease in depths and a gradual decrease in species diversity of aquatic plants. The old lakes of low and middle floodplain level can be in a state of dynamic equilibrium for a longer period of time and maintain high diversity of aquatic vascular plants due to periodic flushing by flood waters, while their drainage will occur more frequently.

A comparison of oligochaete communities of different landscapes in the upstream water of two large rivers, which flowing through the European Northeast of Russia – Pechora and Vychegda. A high diversity of oligochaetes (42 taxa) was found, with species common to both rivers comprising only 26% of the fauna. The family Naididae prevailed in species richness in both rivers. Dominant species included Lumbriculus variegatus, Nais communis, and Propappus volki in the Pechora River and in the Vychegda River – Nais bretscheri, Stylodrilus heringianus, Spirosperma ferox, Limnodrilus hoffmeisteri, and Potamothrix hammoniensis. It was shown that the diversity in the studied parts of the rivers is primarily based on a large number of rarely encountered species. Calculations of diversity indices revealed opposite trends for the oligochaete communities in the upper reaches of the Pechora and Vychegda rivers. For the Pechora River, an increase in alpha diversity, expressed by the Shannon (H_N) and Simpson (1-D_S) indices and species richness, was observed from the upper (mountainous) to the lower (plains) section. Conversely, for the Vychegda River, a decrease in diversity downstream was noted. The comparison of faunas between the rivers (beta diversity), expressed by the Whittaker index, showed higher diversity of oligochaete communities in the upper reaches of the Pechora River.

Based on 10 microsatellite loci of nuclear DNA, the analysis of the genetic variability of perch Perca fluviatilis (L., 1758) from four reservoirs of the Sebezhsky National Park, Sebezhsky district of the Pskov region, which are part of a single lake-river system, was carried out for the first time. The average estimates of the allelic diversity of microsatellite loci and the observed heterozygosity were A = 8.87 and H_E = 0.694 and did not significantly differ between the studied localities. The overall genetic differentiation of perch was θ = 0.002. 95% CI (–0.0007; 0.005) and was non-significant. The population-genetic structure based on the studied multilocus genotypes has not been revealed by the Bayesian analysis method. The data obtained indicate a high level of gene flow in perch throughout the studied water area and make it possible to assume the presence of a genetically unified panmix population in the system of Sebezh lakes and rivers.

Blood parameters of Siberian roach affected by Haff disease from Lake Kotokelskoye (Lake Baikal basin) are presented for the first time. In 2008, the lake experienced an ecological catastrophe: for the first time in Eastern Siberia, an outbreak of Haff disease occurred. After the onset of toxicosis, the studied individuals showed signs of dyserythropoiesis and disturbances in leukopoiesis – degenerative changes in erythrocytes and leukocytes, the development of anemia, inflammatory processes and a decrease in the number of lymphoid cells, initiated by a combination of negative environmental factors, including, probably, the impact of cyanobacterial products. Comparison of the hematological parameters of roach from the transformed lake with those of roach from a healthy area (Chivyrkuisky Bay of Lake Baikal) 6 years after the outbreak of Haff disease showed the presence of destabilization processes in the immune and hematopoietic systems.

In ten small anthropogenic reservoirs located in the Cis-Urals, fish were caught and water samples were taken to analyze the content of dissolved mineral forms of the nitrogen. Fluctuating asymmetry indicators of the seismosensory canals pores number in four paired dermal head bones of European perch individuals were determined. It was found that these indicators are positively and statistically significantly related to the average nitrate content in the studied reservoirs in late spring. It was also noted that the relative abundance of the European perch in fish communities of these reservoirs decreases with an increase in the content of dissolved mineral nitrogen. The identified trends are discussed in two aspects of the possible effect of nitrates on individuals of this fish species: toxicological and trophological.

A new species of diatoms, Hippodonta makarovae sp. nov., is described using scanning electron microscopy. The new species has a valve shape similar to other species of the genus, Hippodonta hungarica Grunow and Hippodonta pumila Lange-Bertalot, Hofmann & Metzeltin, but differs from them in the main diagnostic quantitative features: the length and width of the valve, the number of striae and lineolae in 10 µm.

The composition of leucocytes in peripheral blood, head kidney (pronephros) and spleen of European pink salmon was studied. In peripheral blood and pronephros, lymphocytes predominate among leucocytes, while in spleen immature or blast forms of cells prevail. The proportion of content of different forms of leukocytes depended on sex and structural and functional characteristics of tissues and organs. It was found for the first time that after the change of habitat from marine to freshwater there are significant changes in the blood leucogram. The detected decrease in the proportion of lymphocytes with simultaneous increase in the number of neutrophils and blast cell forms indicates a decrease in lympho- and increase in myelopoiesis. Similar changes were recorded earlier in the leukogram of young pink and chum salmon during smoltification. It is assumed that these differences are one of the mechanisms of adaptation of salmonid fish to habitat change.