The article presents the results of an anatomical study of vegetative shoots of North American Acer negundo L. found in Khabarovsk. It was found that annuals remained covered with epidermis during the winter and are not replaced by periderm. Formation of periderm is observed in shoots starting from the second year of vegetation. The formation of phellogen is noted in the subepidermal layer. Periderm appears in separate fragments, and not as a continuous ring around the circumference of the shoot. It was concluded that this species lacks complete maturation of the integumentary tissues of annual shoots. Presumably, this feature is constitutional and taxon-specific.

Understanding the impacts of alien species on nature and man is crucial to setting priorities for managing invasions, and classification by impact type and ranking of species on this basis is a prerequisite for such decisions. The impact on native species, natural communities, and human life was assessed for 147 invasive alien plant species of European Russia using the Generic Impact Scoring System (GISS). The GISS protocol includes both ecological and socioeconomic criteria and is based on published data (in this study, 689 publications were used for scoring), taking into account the maximum impact in the secondary range. Among all the indicators, the impact on agriculture (crop production) prevails, while among the ecological indicators, the highest scores are for the impact on ecosystems and indirect impact on different biotic groups, including competition. An measure of species invasiveness is proposed taking into account the spread of the species as invasive in the regions of European Russia. Ranking of species by the indicators obtained revealed a relatively good correspondence with the list of species recommended by experts as the most dangerous alien species in Russia, but the choice of priorities among them is difficult without an objective impact assessment. In general, the use of standardized impact scoring schemes and a transparent procedure for determination of the impact status of alien species provide a more reliable approach to setting priorities in management and assessing the risks of invasions than expert opinion alone. A list of species has been suggested for which legislative and practical measures in order to limit their distribution are necessary first of all.

The invasion of the species of the genus Tachycines into Russia occurred at the end of the 19th century, when T. asynamorus was discovered in St. Petersburg. Almost 100 years later, another species of this genus, T. coreanus, was found in the Russian Far East. Data on the history of the distribution of these two synanthropic species are presented, as well as information about their behavior, biology and ecology.

The impact of the invasion of Viviparus viviparus (Linnaeus, 1758) into the lower reach of the Ob River Reservoir on the biochemical quality of the fish food resources was assessed. In the invasion of V. viviparus, a decrease in the weighted average content of essential polyunsaturated fatty acids—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—was observed in the biomass of zoobenthos. However, the biomass, production, and productivity of EPA and DHA in native zoobenthos remained unchanged, as the invasive mollusk occupied a vacant trophic niche. In the river area under study, benthivorous fish after the invasion of V. viviparus can potentially receive the same amount of polyunsaturated fatty acids—essential for their growth and development—from zoobenthos production as before.

The neutral genetic diversity (cytochrome b gene and 12 microsatellite loci) was assessed for populations of the semi-commensal species striped field mouse (Apodemus agrarius Pallas, 1771) in five parks of Moscow located in areas with different degrees of urbanization and in two suburban locations in the Moscow Region. It is shown that the most genetically isolated population is the one which represents a distinct genetic cluster with a reduced level of diversity and is revealed from the park located closer to the city center (Neskuchny Garden). The level of genetic differentiation among populations inhabiting other city parks was much lower. This pattern differs from from that previously observed for the allelic diversity of the adaptively significant exon 2 of the DRB gene (MHC). It is assumed that the rate of accumulation of changes in neutral genes is significantly lower than that for genes responsible for the formation of adaptations, for example, to a parasitic load. The data obtained on the genetic diversity of the striped field mouse in Moscow suggest that the condition of city populations of the species more closely aligns with the “urban facilitation” model, rather than the “urban fragmentation” model (according to Miles et al., 2019). Given this, as well as the potential epidemiological risks, it is important to pay attention to the need for ongoing monitoring of urban striped field mouse populations in Moscow and other cities where this species inhabits.

The first finding of the boring polychaete Dodecaceria concharum in the shells of the Icelandic scallop Chlamys islandica from the Barents Sea is reported. The species identification of the polychaete was established using molecular genetic analysis. It was found that the polychaetes form Y-shaped passages in the shells of the mollusks in the overwhelming majority of cases, which can lead to a violation of the integrity of the shell and a decrease in their physiological activity. An association was found between the polychaete infestation and the presence of boring sponges of the genus Cliona, indicating a complex destructive effect on mollusks. The results obtained emphasize the need for further research into the dynamics of infestation of the scallop and assessment of its consequences for the commercial population.