Heavy metal bioaccumulation in the tissues (fur, muscles, liver, and bones) of free-living striped field mouse (Apodemus agrarius) was studied in four Moscow parks located at different distances from the city center and in areas with varying degrees of anthropogenic impact. The content of eight heavy metals (Fe, Mn, Zn, Cr, Ni, Sr, Cu, and Pb) and metalloid As was quantitatively analyzed by X–ray fluorescence analysis. The accumulation of heavy metals in the tissues and organs of mice living in the studied parks has been shown to occur in different ways. Most of them accumulate in fur, less in muscles, liver and bones (with the exception of Sr, which did not always have the highest concentration in fur, and Ni, with the maximum in muscles). Significantly higher concentrations of the metals were found in samples from the Filevsky Park (higher concentrations were noted for Mn, Fe, Cu, Zn, Cr, and Ni). Sr and Pb accumulation in fur was higher in the Neskuchny Garden and the Ostankino Park, respectively. The Terletsky Park is the most distant from the city center; it is the least polluted one in terms of bioaccumulation in fur, muscles and liver, despite the high score of environmental disadvantage. Thus, metal bioaccumulation occurs in different ways in the tissues and organs of free-living striped field mice, while the distance from the city center and the comprehensive environmental well-being score do not always affect this indicator. To assess the environmental situation in different parts of the city, it is necessary to develop a more complex analytical panel, taking into account the seasonal and spatial dynamics of the circulation of pollutants, their cumulative effects and different metabolic mechanisms.

The big and little Baikal oilfish are endemic to the Baikal Lake, being the most numerous fish species there. Only these two species make up the group of pelagic fish of Lake Baikal. The Baikal oilfish are characterized by a dispersed vertical distribution, from the surface to a depth of 1000 m or deeper. This study provides a description of the current situation regarding parasite infestation in the big and little Baikal oilfish and, for the first time, provides an analysis of changes in the fauna and numbers of parasites in the age series of these endemics of Lake Baikal. There are 14 and 15 species in the parasite fauna of the big and little Baikal oilfish, respectively. In total, the parasite fauna of both host species is represented by 17 species, of which 12 species are common to both fish species. There is a high degree of similarity in the species composition of parasites in the Baikal oilfish, however, trematodes were found in the little Baikal oilfish only, which indicates differences in ecology between the two host species. A discrepancy was revealed in changes in the species richness of parasites in the age series of the little and big Baikal oilfish, namely: it increases in the first host, while in the second host, the species richness of parasites first increases, then decreases in older age groups. This discrepancy between the Baikal oilfish is associated with differences in the composition of the food bolus in the middle and older age groups of these fish. 

The level of genetic diversity and differentiation of populations of the Chinese sleeper Perccottus glenii from water bodies of the Volga and Irtysh basins was assessed based on ISSR markers. In the studied part of the Volga basin, the proportion of polymorphic loci (P) of the Chinese sleeper was 80.4%, genetic diversity (h) was 0.26. All studied populations of the Chinese sleeper from the Kuibyshev Reservoir area (Ulyanovsk, Samara region, Togliatti) were genetically weakly differentiated and originate from a single source of invasion. The polymorphism and genetic diversity of the Chinese sleeper in the Irtysh basin were higher than in the Volga region and amounted to: P = 98.2%, h = 0.33. Genetic differentiation between the populations of the Ipkul Lake and the Tobol River (Tyumen region) was weakly expressed (GST = 0.07), the gene flow between them was significant, which indicates their recent divergence or the origin of one population from another. The genetic differentiation between the populations of Lake Berezovo (Kurgan region) and Lake Maloe Ploskoe (Kazakhstan) was high (GST = 0.31), which may indicate different sources of invasion of the Chinese sleeper in southern Siberia and northern Kazakhstan. Data on the higher polymorphism of the Chinese sleeper in the Irtysh River basin, as well as significant genetic differentiation between its populations in the Volga and Irtysh basins (GST = 0.40), only partially confirm the generally accepted hypothesis of the colonization of Siberia by the Chinese sleeper through the South Ural invasion corridor, indicating the presence of several heterogeneous invasion sources in the Ob–Irtysh basin. 

The paper reviews the current distribution, status, and abundance of the nominate subspecies of Great bustard (Otis tarda tarda L.) within its global range. A distribution map of the Great bustard is provided based on a review of literature data on the abundance and trends in different parts of the range for the period from 2010 to 2025. According to available data, the total population size is estimated at 29,600 to 33,000 birds. Possible causes for the decline in the Great bustard numbers in different countries are discussed. The status of this species in the Russian Federation is described, with an emphasis on the Saratov and Volgograd regions, where it occurs during its nesting season. A distribution map of the European subspecies of bustards in the Russian Federation is provided. The regions of the Russian Federation are described where this species is currently found, its habitats used during the breeding season, and the routes of its migration to and from its wintering grounds. The total population of bustards in the Russian Federation is estimate as 2500 individuals, but this number is approximate since it is based on different counting methods, including both detailed and comprehensive surveys of entire territories and expert assessments. The main threats to bustard populations in the Russian Federation are the intensification of agricultural production through the use of chemicals, the development of fallow fields and virgin lands to cultivate more oilseeds and winter grain crops, collisions with overhead power lines, and illegal hunting. A significant negative role during the bustard nesting period is played by the high number of predatory mammals and birds of prey, such as the white-tailed eagle. 

The influence of low-intensity electromagnetic fields (EMF) on the sensitivity of Daphnia magna Straus, 1820 to two model toxicants, namely, potassium dichromate (K2Cr2O7) and cadmium sulfate (3CdSO4ꞏ8H2O), was investigated. Two EMF exposure modes with a frequency of 30 MHz were used, namely: with a constant amplitude and an amplitude modulation (AM) mode with a frequency of 50 Hz. The EMF effect on the sensitivity of Daphnia was assessed by observing changes in the survival of the crustaceans placed into toxicant solutions after EMF ex- posure. Differences in the sensitivity of Daphnia exposed to EMF to the studied toxicants were manifested in the dynamics of survival reduction in salt solutions over a 96-hour exposure period. The most noticeable differences between the effects of cadmium and dichromate on the crustaceans were observed in the AM mode. To analyze the inheritance of traits, a comparison was made of the effects of heavy metals on the survival of offspring from directly exposed females (series I) and the unexposed offspring of exposed females (series II). The offspring of Daphnia from exposed females (series II) exhibited higher resistance to еру toxicants compared to series I. To explain the increased resistance of the offspring from exposed crustaceans, the possibility of adaptive mechanisms being triggered in response to the damaging informational impact of EMF on the genetic material of the females is discussed.

The article presents the results of our research on the population size, distribution, and characteristics of thrushes in Northern Eurasia within the 1990 USSR boundaries. The study utilized data from the Zoological Monitoring Laboratory’s database, collected intermittently between 1880 and 2022 (primarily since 1960) during bird surveys conducted from May 16 to July 15 along routes with a total length of approximately 165,000 km. Based on factor classification, six types of thrush populations were identified, whose boundaries correlate with climatic and geographical environmental features. Additionally, seven subtypes of communities were distinguished, varying in boundaries depending on forest coverage and thermal conditions. It was found that thrush population density and species richness increased in southern and western regions, while thrushes are absent in polar deserts and Arctic tundras. The research methodology, including cluster analysis data processing and the introduction of null species to account for extreme habitats, enhanced the informativeness of the classifications. The study results can be applied in conservation activities and ecosystem health assessments.

Data on the spatial dynamics of the content of chlorophylls a, b and c, carotenoids and pigment indices of phytoplankton and periphyton in small rivers (tributaries of the western coast of Lake Ladoga) are presented. The chlorophyll a content of river phytoplankton varied from 1.8 to 49.8 mg/m3, in periphyton – from 8.5 to 262 µg/g of substrate, that corresponded to a mesotrophic status, and in some river parts – to a eutrophic status. The chlorophyll a content of phytoplankton decreased towards the river mouth in the Avloga and Vyun rivers, in the Morye river it increased downstream, and in the Sosnovka river it was distributed relatively evenly. The chlorophyll a content of periphyton increased downstream in the Avloga and Sosnovka rivers, while in the Morye and Vyun rivers it decreased. In the total of chlorophyll pigments in both algocenoses, chlorophyll a prevailed, its fraction being 56–96%. The ratios of additional pigments (chlorophyll b and c) indicated the predominance of green algae, diatoms, and euglenoid algae in the studied communities. In general, comparison of pigments and carotenoids has revealed favorable conditions for the functional activity of both phytoplankton and periphyton communities, that allows classifying the studied rivers as slightly polluted.  

The influence of lanthanum, copper and their mixture on the larval form of chironomid midges Chironomus riparius Meigen, 1804 was assessed. An insignificant increase in the mortality of larvae with increasing concentration of La³⁺ in water was shown (rs = 0.70, when p = 0.19). The maximum mortality of 47% was recorded in a solution containing 160 µmol/L La³⁺. A comparison of low concentrations of La³⁺ and Cu²⁺ and their equimolar combinations (0.8 and 0.16 μmol/L) showed that all solutions reduced the survival rate of individuals (2.3 to 5.2 times), except for the solution where the copper concentration was 0.8 μmol/L. The survival rate of larvae was 3 times higher than the control values (essential effect). The linear dimensions of the test organisms in all experimental variants were significantly lower than in the control. The maximum decrease in morphometric parameters (length) under the influence of a mixture of the salts was 18–19% compared with the control. Consequently, the danger of lanthanum and its combination with copper for benthic organisms is shown using the example of Ch. riparius, which has not previously been reported. 

Data on the mercury (Hg) content in the muscle tissue of some fish species (Perca fluviatilis, Rutilus rutilus, Blicca bjoerkna, Alburnus alburnus, and Clupeonella cultriventris) are presented, they live in the Gorky reservoir, as depends on their body length. The research was conducted in 2023 at eleven stations of the river, lake-river and lake sections of the Gorky reservoir. Differences in the Hg content in small and large perch individuals were revealed, a more in- tense mercury accumulation being observed in young individuals. The metal content in the muscles of the studied fish species decreased in the following sequence: Perca fluviatilis ≥ Clupeonella cultriventris ≥ Alburnus alburnus ≥ Blicca bjoerkna ≥ Rutilus rutilus. The Hg concentration in the muscles of the fish from the Gorky reservoir is shown to be at a level comparable to the data recorded in other reservoirs.

The work analyzes the bottom and lithophilic vegetation of coastal cliffs of the Abrau Peninsula within the Abraussky Natural-Historical Reserve and its eastern border. Extreme unevenness in the distribution of phytocenoses was noted, associated with the relief heterogeneity. Landscape profiling was carried out with a detailed description of transects, which made it possible to assess features of the spatial distribution of plant communities on abrasion-accumulative banks. 70 species of vascular plants and 17 species of algae were found, including 15 endemics, 27 species included in the Red Data Book of the Krasnodar region, and 9 species from the Red Data Book of the Russian Federation. An analysis was carried out for the purity of coastal waters using saprobity coefficient (1.94) and Cheney’s coefficient (1.42). The environmental protection coefficient (16.4) was calculated. Measures are proposed to optimize the environmental regime of the nature reserve.