Aim. The aim of this work was to briefly summarize the current understanding of the phenomenon of echolocation in the order of bats (Chiroptera Blumenbach, 1779).
Discussion. The paper discusses: the place of bats among other taxonomic groups of animals that have the ability of echolocation; the history of the discovery of "ear vision" in bats by L. Spallanzani in the 18th century; the first scientifically based assumptions regarding the use of ultrasound by bats and the discovery of this phenomenon in the middle of the last century; methods for emitting and receiving ultrasound by various taxonomic groups of bats; physical patterns underlying the propagation of ultrasonic waves; characteristics of the returned echo and algorithms for echolocation in bats; echolocation interactions between insectivorous bats and nocturnal moths and possibilities for ultrasonic monitoring of bat populations.
Conclusion. The inclusion of ultrasound monitoring of bat populations in integrated ecological and virological studies could form a new point of growth in systems to ensure biological security at both national and global levels.

Aim. Analysis of the first data regarding the arrival of the predatory ctenophore Beroe cf. ovata in the Caspian Sea and assessment of possible effects of its introduction for the Caspian ecosystem.
Material and Methods. The material was obtained in the deep-water region of the western shelf of the middle Caspian Sea in the first ten days of October 2020. Zooplankton samples were collected using a Juday plankton net (0.1 m² opening, 180 μm mesh size). Large ctenophores were collected using a big cone plankton net (CB) with a 0.5 m² opening, 500 μm mesh size. Samples were taken at five stations in the 0-40 m layer. Combs larger than 5 mm were counted and measured on board the ship. The number and size of small ctenophores, larvae and eggs were determined in zooplankton samples fixed with formalin to a final concentration of 4%.
Results. The presence of a new alien Beroe cf. ovata was recorded in the Dagestan shelf waters of the Caspian Sea in the beginning of October 2020. The average number of Beroe cf. ovata for five stations was 22 ind/m² and the biomass was 6.15 g/m². Larvae and small individuals from 5 to 20 mm in size predominated. Mnemiopsis leidyi was absent in the area investigated. The structure of mesozooplankton was dominated by the small copepod Acartia tonsa, which accounted for 92% of the zooplankton community and 78% of its biomass.
Conclusion. The size structure of the B. ovata population with a predominance of larvae and small individuals indicates a recently completed breeding cycle and adaptation of the ctenophore to the conditions of the Caspian Sea. The first impacts of the new invasive ctenophore on the population of M. leidyi were demonstrated. This event may be the beginning of a new stage in the evolution of the Caspian Sea ecosystem and the restoration of its bio resources affected by the invasion of Mnemiopsis leidyi. The structure of mesozooplankton with total dominance, in abundance and biomass, of the small copepod Acartia tonsa did not differ from that in the previous period, indicating that the Caspian zoocenosis did not respond to the short-term reduction of the impact of M. leidyi. A brief analysis of the history of the introduction of ctenophores to the Black and Caspian Seas is presented and their impact on ecosystems and biological resources of these seas is studied. Based on longterm observations of the invasive ctenophores' interactions in the Black Sea, the possible outcomes of the penetration of Beroe cf. ovata in the Caspian Sea are discussed.

Aim. To identify the structural features and assess the current condition of woody species in the beech forests of Dagestan, Russia.

Material and Methods. Research was based on the analysis of data from 69 sampling areas located in various physical-geographical regions of Dagestan. A detailed accounting of individual specimens of all age groups of each species was undertaken in the sampling areas. The total area surveyed was 43,125 m². In total, 11,446 individuals of different species were involved in the statistical analysis, of which 1,974 form a tree tier, in which each individual is evaluated according to a scale of condition categories.

Results. A study of the structure of beech forests showed the participation rate of Fagus orientalis Lipsky to be from 7.5 to 8.5 points. The average age of the upper sub-level of beech in the foothills was 110 years and in the highlands 160 years. For most woody species the age spectrum was sinistral and incomplete. Beech with a full-membered age spectrum were observed in the beech forests of the southwestern sub-region and in the high mountain region. A general trend is observed of deterioration of the condition of individuals in the transition from the upper to the lower sub-level. The average condition of beech individuals within the tree tier is 1.4 points. The condition categories of other species are characterized as being generally closer to 'weakened'.

Conclusion. The results obtained regarding the structure and condition of woody species in the beech forests of Dagestan confirm the highly edifying role of beech. The greatest negative impact is exerted by the anthropogenic factor, which is confirmed by the incompleteness of the beech age spectrum and the low participation rate of the old-growth generative group and of the post-generative period.

Aim. To investigate the effect of certain antibiotics - tylosin, oxytetracycline and benzylpenicillin - on the potential nitrifying and cellulolytic activity of gray forest soil using laboratory model research methods.
Material and Methods. The object of the research was agricultural gray forest medium loamy soil. The study was carried out by conducting laboratory model experiments. The analysed samples were incubated at 27°C and in the absence of illumination for 30 days and then subsequently analysed for cellulolytic activity (by the application method) and nitrification activity (by the potentiometric method). The taxonomic composition of the bacterial community of the studied soil was established based on analysis of amplicon libraries of fragments of ribosomal operons of 16S rRNA genes by the NGS method.
Results. The largest number of nitrification organisms in the soil studied were archaea of the family Nitrososphaeraceae which are autotrophic ammonium oxidants. Most resistant to the effects of the antibiotics used was cellulolytic activity which was suppressed only by the addition of tylosin and its admixture with oxytetracycline. The nitrification activity of the soil varied depending on the concentration and preparations applied, the greatest inhibitory effect being exerted by tylosin. Antibiotic mixtures slightly enhanced the nitrification process at 50-100 mg/kg and were suppressed in the range of 150-700 mg/kg.
Conclusion. Once in the soil, the antibiotics studied are capable of both stimulating and inhibiting enzymatic processes. Mixtures of antibiotics rather than their individual applications produce the greatest impact. In medium loamy gray forest soil the presence of antibiotics is more dangerous to nitrification activity.

Aim. The study of temperature anomalies in the western Caspian Sea based on space imagery materials in order to detect upwelling phenomena.
Materials and Methods. We used temperature indicators of seawater for the summer season of 2017 when a sharp decrease by more than 2 °C in average daily temperature occurred. Space images were obtained from the specialized centres of Ocean Color NASA, Earth Science Data Systems NASA and SATIN. Remote sensing data were processed using SeaDAS and ArcGIS programs. Ground data were obtained from the resources of the Unified State System of Information about the Situation in the World Ocean (ESIMO). An ArcGIS database was created and maps compiled.
Results. The first upwelling occurred on 9-17 June 2020. The minimum water temperature in the Makhachkala area was 14°C with an increase in salinity to 12%o over an area of 1,500 sq.km. An increase in the content of dissolved oxygen of up to 9.70 mg/l and pH 8.64 was recorded. A second upwelling of medium intensity occurred from 19 June-July 1 with a minimum temperature of 17.9C. The decrease in temperature was 2.8°C with an increase in salinity by 1%o. The surface area was 454 sq.km. A third case of upwelling was recorded from 26 August-September 1 and was characterised by a decrease in water temperature of 7.4C (near the coast, 17.1°C). The average salinity increase was 0.32%o while the 0₂ concentration was 8 mg/l over an area of 500 sq.km.

Conclusion. Due to its large size, the Caspian Sea is characterised by spatial inhomogeneity of oceanological parameters, which can be recorded based on the results of processing satellite images and their verification using ground data. In the western part of the sea the upwelling is periodic and of different scales.

Aim. To summarise and analyse data on the species diversity, distribution and substrate spectra of wood-inhabiting basidial macromycetes growing on fruit trees in the Belgorod, Voronezh, Kursk, Lipetsk, Oryol and Tambov Regions.
Material and Methods. The work involved a critical examination of literature sources, LE, OHHI, and VU herbaria. We undertook field researches in 2019-2020, identified specimens collected based on light microscopy techniques and isolated the basidial fungi in a pure culture.
Results. Data on 97 species of basidial macrofungi from 68 genera associated with Malus, Pyrus and Prunus wood in the Central Black Earth Region are summarised. Antrodia serpens and Ceriporia torpida are newly known to Russia. 65 new dikaryot-ic strains for 22 species of Agaricomycetes have been introduced into the LE-BIN. A total of 65 species are associated with Malus, 34 species with Pyrus and 29 species with Prunus. Five species (Lyomyces crustosus, Stereum hirsutum, Trametes hirsuta, T. ochracea and T. versicolor) grow on all three genera of host. These species specialise in fruit trees include Sarcodontia crocea and Phellinus pomaceus.
Conclusion. Pathogenic activity has been clearly observed for 32 species of fungi found on trunks and branches of living trees, causing necrosis and trunk rot. Furthermore, it is recommended that regular phytopathological monitoring of orchards should be carried out, taking the group of xylotrophic fungi into account.

Aim. To estimate the humus content and stocks of arable chernozems of two soil-ecological zones (Predcaucasia and Yuzhno-Russkaya) within the Rostov region, as well as the possibility of the optimization of the state of their humus under current conditions.
Material and Methods. The following data sources were used: soil and general geographic information accumulated in the Soil-geographic Database of the Russian Federation information system, the Red Book of the Rostov Region Soils database, digitised archived soil survey data of 1977-1995 and agrochemical monitoring data of 2012-2017.
Results. The stabilisation of the humus content of the arable chernozems of the Predcaucasian zone in recent decades has been demonstrated and can be explained by a decrease in the dehumification rate under minimal tillage. The average humus content in the soils of the Yuzhno-Russkaya zone decreased by approximately 0.5% during the same period, which may be caused by the high proportion of row-crops cultivated in an erosion-prone area. The current average humus content in arable chernozems is very low, it is close to the critical level, below which crop yield is decreased despite of sufficient mineral fertilizers using.
Conclusion. The main causes of soil dehumification in the region are agrogenic humus mineralization due to a constant deficit of compensating amounts of fresh organic matter, deflation of fine soil material from ploughed surfaces and water erosion. The optimisation of land use structure and crop structure, which takes into account the characteristics of these territories, is required to reduce the intensity of these processes under current conditions.

Aim. To demonstrate the high adaptive abilities of dairy cattle to various ecosystems and natural zones of the Lower Volga at different times of the year. For the study we selected farms located in the steppe and semi-desert natural zones of the Volgograd region where animals of different breeds are reared.
Material and Methods. Analysis was undertaken of the main indicators of raw milk quality, amino acid composition and environmental safety. Animals of all farms studied showed fairly high indicators of milk productivity in the climatic conditions of the Volgograd region, according to the standards of the breeds investigated.

Results. The content of essential amino acids in cow milk for all groups varied depending on the breed and period of the year, generally reaching maximum values in winter. The calculation of amino acid scores showed that lysine is a limiting amino acid in animals of the Holstein-Friesian breed in the summer and autumn periods of lactation. The determination of chemical elements in milk during the summer period of lactation showed that all indicators are within acceptable concentrations, including heavy metals (lead, arsenic, cadmium, mercury).
Conclusion. The research conducted confirms compliance of raw milk with standards in all farms studied for the main controlled indicators of quality and amino acid composition, content of chemical elements and allows recommendation of the milk produced for the production of all types of dairy and fermented milk products.

Aim. Selection and analysis of index images suitable for deciphering the vegetation cover in the conditions of inner mountain Dagestan.
Methods. The study was carried out on the basis of multi-temporal satellite images of high spatial resolution, obtained by the imaging system of the Sentinel-2 series satellite, using methods of digital processing of geoimages. Processing was carried out using the capabilities of the Google Earth Engine geoservice.
Results. Multi-temporal index images were obtained for the territory of inner mountain Dagestan. The time series of seasonal changes in the indices (NDVI, SAVI, EVI) were analyzed, making it possible to reveal the phenological patterns of vegetation and to map the vegetation cover on this basis. Schemes for decoding vegetation have been created by which areas are distinguished according to the following characteristics: devoid of vegetation, herbaceous vegetation of varying degrees of density or woody (deciduous and coniferous).
Conclusion. When studying vegetation cover using index images in a range of natural conditions, it is necessary to take into account the natural features of the territory, as well using additional sources of spatial information including field research methods.

Aim. The aim of the research has been: to study the theoretical basis of the application of assessment of economic damage from environmental pollution in the field of environmental auditing and accounting, to identify problems in existing methods and approaches and to propose specific ways to solve them taking into account current legislation and international experience.
Material and Methods. The research carried out by the authors was based on the provisions of current legal regulations in the fields of environmental safety and environmental protection, damage assessment in the environmental sphere together with data from scientific articles by both domestic and foreign experts in the field of environmental auditing. The study was conducted using theoretical methods of research including analysis, deduction and prediction.
Results. The authors propose moving away from traditional cost (taxation) methods to the consolidation in regulatory practice of a single approach to the assessment of economic damage taking into account actuarial valuation methodology, application of sanctions instruments to those unscrupulously infringing environmental regulations and the possibility of discounting the costs of restoring the environment and damage done to public health.
Conclusion. Adoption of common approaches and principles in the assessment of economic damage will help eliminate negative manipulations when imposing economic sanctions on those unscrupulously engaged in activities impacting on the environment and will provide an opportunity to improve the environmental situation and public health in the long term.

Aim. The study of the genus Melanotus from the collection of the Institute of Zoology of the Scientific Center of Zoology and Hydroecology of the National Academy of Sciences of the Republic of Armenia taking into account new taxonomic and chorological data.
Material and Methods. Scientific material was identified after desktop processing and preparation of genitalia according to current data on the genus Melanotus.
Results and Conclusion. We determined 21 species of the genus Melanotus in the collection from Europe, the Caucasus and Middle Asia, 12 species being recorded from the territory of Armenia. The collection of the genus Мelanotus in the Institute of Zoology includes species endemic to Armenia (M. gedeoni Mardjanyan, 2015, M. platiai Mardjanyan, 2015, M. khnzoriani Mardjanyan, 2015), to Tajikistan (M. fragilloides Dolin, 1988, M. vidualis Gurjeva, 1988) and to Iran (M. dichroides Platia & Gudenzi, 1999, M. richterae Mardjanyan, 2015). Three species, M. castanipes Paykull, 1800, M. fulvus Reitter, 1891 and M. sladkovi Dolin & Atamuradov, 1986 are recorded for the first time for Armenia. M. rustamovi Dolin & Atamuradov, 1987 is the first record for Tajikistan and M. persimilis Dolin & Latifi, 1988 for Turkmenistan.

Aim. To analyse seasonal changes in the frequency characteristics of wind speed and direction in coastal Dagestan, namely the urban districts of the cities of Makhachkala and Derbent, from the point of view of wind power potential.
Material and Methods. The research was based on time series of wind speed and direction for the period 2011-2018, obtained as a result of observations at the Makhachkala and Derbent weather stations. As a mathematical research tool, a continuous wavelet transform with a complex Morlet wavelet function was used.
Results. According to the results of analysis, it was found that the main frequency of fluctuations in the time series is one day and one-day periodicity in the time series has pronounced seasonal changes. Also, differences in seasonal changes of one-day periodicity for wind speed and direction between the regions of Makhachkala and Derbent were established and described.
Conclusion. The parameters considered in assessing seasonal changes in the dynamics of wind speed and direction can be used as additional parameters for the classification and clustering of regions to identify the best areas of wind power potential.

Aim. To determine the presence or absence of specific IgG antibodies against SARS-CoV-2 antigens in outpatient clinic staff and to compare clinical and immunological features from April to August 2020.
Materials and Methods. The control group comprised 386 employees of the Novosibirsk City Clinical Polyclinic №13.The determination of IgG antibodies against SARS-CoV-2 antigens in blood serum was performed by using the ELISA method. A real time method of reverse transcription and polymerase chain reaction was used to extract RNA SARS-CoV-2 from nasopharyngeal and oropharyngeal swabs.
Results. Specific IgG antibodies against SARS-CoV-2 antigens were detected in 32 (8.42%) employees of the polyclinic. Antibodies were not detected in 91.58% of employees. 9 members (28.12%) had clinical symptoms of varying degrees of disease severity in the group of employees with the presence of antibodies, 4 members of this group (12,51%) had bilateral community-acquired pneumonia with signs of COVID infection, another 5 members (15.61%) with antibodies had signs of ARVI of mild and moderate severity. RNA SARS-CoV-2 in the group of employees with the presence of antibodies and clinical implications was not detected in any case; 23 (71.88%) members with the presence of IgG-antibodies did not have clinical implications of the disease.
Conclusion. The presence of specific antibodies against SARS-CoV-2 in employees with clinical implications of COVID-19 without detection of the RNA virus in the biological material is a retrospective confirmation of the etiology of the transferred infection. The detection of specific antibodies in persons who did not have clinical implications can serve as confirmation of the asymptomatic course of the transferred coronavirus infection.

Aim. Study of the influence of drinking water quality on the ecologically-dependent morbidity of the population of the Republic of Dagestan.
Material and Methods. Methods of current and retrospective analysis of regional health indicators and methods of mathematical-statistical and medical-geographical analysis were used. Statistical processing of the results was carried out using the STATISTICA and Excel software packages. When carrying out laboratory studies on the quality of drinking water, we used a Lumex atomic absorption spectrometer "MGA-915MD".
Results. Numerous hygiene studies indicate the direct impact of unsatisfactory drinking water quality on the health of a population. The relationship between sanitary and chemical indicators and the incidence rate for a number of nosological forms has been proven. It is generally accepted that human health is influenced by lifestyle factors (working, living and relaxation conditions), heredity and the ecological condition of the area of residence, including the quality of drinking water. Although it is not possible to differentiate the share of the negative effect caused by the consumption of poor quality drinking water but the incidence of certain nosological forms (cancer of the esophagus, gastrointestinal tract and kidney diseases) in the those regions of the Republic of Dagestan under consideration correlates with the characteristics of drinking water.
Conclusion. The problem of pollution of water supply sources for the population in the dynamics of the long-term remains a priority concern. The quality and safety of drinking water are decreasing, which cannot but have a negative impact on public health. Correlation linkages between indicators of drinking water quality and oncological morbidity of the population were also established in indicators below the maximum permissible concentrations, which corresponds to a typical logistic model of causal relationships and serves as evidence of the high dependence of health disorders on chemical contamination of water supply sources.

Review of the collection of scientific articles "Assessment and geoinformation mapping of the medical and environmental situation in the city of Voronezh" (under the general editorship of S. A. Kurolap and O. Klepikov. Voronezh: Digital Printing, 2019, 219 p.) and of the monograph "Environmental risks of territories of intensive technogenic development" (S.A. Kurolap, O.V. Klepikov, T.I. Prozhorina et al / Under the general editorship of S.A. Kurolap and O.V. Klepikov). Voronezh: Digital printing, 2019. 191 p. The review was written during the period of self-isolation and remote access to the authors' work associated with the COVID-19 pandemic.