The body shape variability of minnow populations in different-size watercourses in the Sylva River basin (the Middle Urals) was investigated by geometric morphometrics. 26 homologous landmarks were used to describe the body shape variability of fish. Four geographically adjacent minnow populations isolated by artificial and natural dams were studied. More than 56% of the variance of inter-group morphological differences in minnows is due to the minnow inhabiting the large watercourse of the main stem (the Sylva River) and its small tributaries (the Lomovka River, the Musorka River, and the Sarga River). The main-stem minnows are distinguished by relatively large eye size, low body, and small short jaws. The tributary minnows are characterized, on the contrary, by relatively high body, small eyes, and long jaws. Along with the revealed significant differentiation of the isolated minnow populations from the main stem and its tributaries, a high level of individual morphological differences was discovered, which indicates some directed change of the fish development trajectory in the population from each stream. The discrimination level of individuals reached 97.9%. A low intra-group diversity of body shape was identified for the minnow population in the large watercourse of the Sylva River with its multi-species ichthyologic diversity. The minnows from the small watercourses of the Lomovka, Musorka and Sarga rivers with their low specific diversity have an increased intra-group body shape diversity. It may indirectly indicate some ontogeny change in the individuals from the small tributaries, related to the formation of a wide range of ontogenetic trajectories and suggests a high phenotypic plasticity of the species. The role of the hydrological regime in small watercourses and the taxonomic diversity of fish communities in the formation of the minnow morphological diversity is hypothesized.

The paper considers the main natural changes associated with climatic fluctuations and economic activity in a clayey semidesert of the Volga-Ural interfluve over the past 250 years. The authors distinguish four climatic periods determined by the humideness of the territory, namely: the mid-18^th century - 1820s; 1830s - 1950s; 1960s - the end-1980s; and 1990s - 2010s. For each period, features of the area are described, related to humidification and human economic activity, and, as a result, changes in flora and fauna characteristics of the region. In the clayey semi-desert in the Trans-Volga region, only the existence and character of aquatic and near-water communities is shown to directly depend on climatogenic factors. Most changes in the animal world of other community types reflect various stages and forms of the economic use of the territory and are only corrected by climatic changes. The ravine forests in lake depressions existed until the 19th century ensured the presence of a complex of ravine-forest species in the regional fauna. After the deforestation of these communities, some part of the species of this complex completely disappeared from the region, some part became synanthropes, and the other one firstly disappeared but later returned to the region, after the appearance of polydominant tree-bush communities in lake depressions and artificial forest belts and gardens on the plain. Because of the strong grazing during an arid climatic period, there was a change of steppe plant associations on the plain to desert ones, so that some steppe animal species also disappeared from the region with some desert ones having come to their place. The plowing of plain areas has led to the appearance of species in the region, which use plowing as their feeding sites. Various forms of human development of the territory have led to the arrival of a number of species from other regions.

The microbiological pattern of the salons of urban public transport is described for the first time with 41 buses of 16 routes as examples. According to orographic features of the Nizhny Novgorod city, all the bus routes were split into three model groups, namely: the high-bank one, the low-bank one, and the inter-district one. The abundance and species composition of microorganisms were estimated using a MALDI mass spectrometer Autoflex (Bruker Daltonics, Germany) and the BioTyper software. 85 microorganism species were detected, identified and assigned to one of the following three groups according to their degree of pathogenicity, namely: 1) conditionally pathogenic microorganisms, often causing infectious diseases; 2) conditionally pathogenic microorganisms causing infectious diseases rarely, and 3) non-pathogenic microorganisms. To characterize the ecological structure of the microbial community of urban public transport, two similarity indices were calculated, namely, Sorensen’s index and Koch’s biotic dispersion index. The species composition was analyzed at two hierarchical levels of the bus route groups (the intragroup and intergroup ones). At the intragroup level, a small number (1-3) of common species were found in each route group represented by S. epidermidis, S. haemolyticus and Acinetobacter lwoffii, which corresponds to a low Koch index value (0.1). At the intergroup level, just 15 common species of microorganisms were found, which corresponds to the value of Koch’s index calculated for the three route groups (0.26). In other words, 26% of species were common for the three route groups analyzed. All the three groups of microorganisms were represented most fully in the inter-district route group, namely: Group 1 - 45%, Group 2 - 53.8%, and Group 3 - 58.1%. Community structure analysis carried out with few ecological indices (Shannon’s species diversity index, Simpson’s index of dominance, Margalefs species richness index, and Pielou’s species evenness index) showed that an increase in the specific diversity of microbial communities is accompanied by a regular decrease in dominance and an increase in evenness. Analysis of the group of dominant species identified in the buses of the three route groups revealed that the species similarity of the dominant species, estimated by the value of Koch’s index, was only 0.14, which could be explained by the presence of only one common species (Acinetobacter lwof-fii). Studies of the microbial community of urban transport present a perspective for solving the sanitary, hygienic and environmental aspects of the integrated problem of ensuring the ecological safety of the urban environment.

Only two large regions with natural vegetation had remained in the Volga River valley by the beginning of the 1970s, namely, the Volga-Akhtuba floodplain and the Volga River delta. The largest part of the remaining valley had been converted to a cascade of artificial reservoirs. The conservation of meadow, marsh and forest plant communities in the Lower Volga, in the semi-desert and desert zones, is due to regular special water releases to the downstream of the Volgograd hydroelectric complex. These artificial water discharges to the Lower Volga valley in the spring-summer period took the place of natural floods. However, in the conditions of regulated water flow, the water rise height during high water diminished, and the duration of flooding of inundated ecotops shortened. In the northern part of the flood-lands, on the dam site of the Volgograd Hydroelectric Power Station, the river bed went deep along a 100 km section. They were dams which became hindering water inflow to the Volga-Akhtuba floodplain during spring and summer floods. They surround agricultural lands with artificial irrigative systems and settlements in the flood-lands. Roads are built on such dams. The recreational use of the Lower Volga valley has increased in the last decades. Before the building of the largest Volga hydroelectric complexes (the Kama, Gorky, Kuibyshev, Volgograd and Saratov ones), in 1954-1955, the Caspian expedition of Moscow State University laid five geobotanical transects in the Volga-Akhtuba floodplain. Subsequently, four of these transects were surveyed in 1982 and in 2008-2013. It was established that xerophytization and ruderalization of the vegetation occurred on all transects. These phenomena were not similar at different sections of the floodplain. They were most pronounced near the Volgograd Hydroelectric Power Station and in places where the valley is narrowing. The main causes of these xerophytization and ruderalization of vegetation are the reduction in the height and duration of floods after the beginning of water flow regulation, the high local grazing, and recreation pressure. Among the invasive species, the most important role in changes of the vegetation cover of the Volga-Akhtuba floodplain is played by Fraxinus pennsylvanica, Conyza canadensis, Bidens frondosa, and Xanthium strumarium s.l. Thus, not all phenomena related to the dynamics of the flora and vegetation of the Volga-Akhtuba floodplain were caused by the restructuring of the Volga hydrological regime after the beginning of its water flow regulation. The invasion of alien plants, the increased recreational load, and changes in the economic use of vegetation have played some role in this process.

The paper presents the results of our ecological monitoring of the status of three springs in the Atyrautsk region and twelve ones in the Western Kazakhstan region within the boundaries of Western Kazakhstan. The following properties of spring water samples are given: temperature, pH, debit, turbidity, total hardness, permanganate index, solid residue, total spring mineralization, dissolved oxygen, cations (ammonium, calcium, magnesium, sodium, and potassium), anions (nitrites, nitrates, carbonates, hydrocarbonates, chlorides, sulphates, and polyphosphates), heavy metals (copper, zinc, lead, cadmium, iron, chrome, manganese, cobalt, and nickel), petrochemicals and phenols in accordance with water quality hygiene standards of Kazakhstan Republic and Russian Federation. Microbiological indicators of our water survey are given (total microbe number, total coliform bacteria, and thermotolerant coliform bacteria) and spring bacterial contamination factors. All springs were found to have small debits except the Tilepbulak spring in the Atyrausk region (a semi-debit one). The water of almost all studied springs was neutral, except the Ainabulak spring in the Western Kazakhstan region, whose water was weakly acidic to violate the standard indicators of RF and KR. The sprigs under study differed by their hydrochemical indicators. The water in most of the springs violated the hygienic standards of RF and KR. In all the springs of the Atyraus region, the hygienic norms were exceeded by iron, chrome, manganese, nickel, and phenol. The water of one spring (the Ashituzbulak) weakly exceeded the accepted norm by petroproducts. High iron concentrations were found in two springs of the Western Kazakhstan region (Taskal-5, Serebryakov), chrome was in six ones (Taskal-5, Krasnenkoye, Tsiganovo-2 (Yegendibulak), Big Itchka, Ainabulak, Serebryakov), manganese was in two ones (Taskal-5, Serebryakov), nickel was in four ones (Taskal-5, Krasnenkoye, Tsiganovo-2 (Yegendibulak), Big Itchka, Ainabulak, Serebryakov), phenol was in five ones (Taskal-5, Krasnenkoye, Tsiganovo-2 (Yegendibulak), Big Itchka, Ainabulak). In the springs of the Atyraus and Western Kazakhstan regions, no deviations from the hygienic norms were found. The instability of microbiological indicators of water was due to the fact that most of the springs under study were located near inhabited places and actively used for living needs and watering of domestic animals. The paper suggests practical recommendations for the rational usage of springs within the boundaries of Western Kazakhstan.

The status of the populations and breeding groups of the Demoiselle Crane Anthropoides virgo (Linnaeus, 1758) depends on changes in the agricultural landscapes stronger than for other cranes, as economic development has affected almost the entire breeding part of its range in the steppes and semi-deserts of Eurasia. The large-scale and intense expansion of agricultural landscapes in the USSR in the 1950-1960s, accompanied by a strengthening complex of limiting factors, caused a sharp decrease in the number of the Demoiselle Crane and its redistribution within its breeding area. In the 1970-1980s the species, took advantage of the agricultural landscape expansion due to the mass transition to breeding on cultivated fields. After the collapse of the USSR in 1991, the reaction of the Demoiselle Crane to the withdrawal of a huge area of agricultural fields and pastures from economic usage in different areas of its distribution proved to be ambiguous. The decrease in the numbers in the south, west and east of the habitat was compensated by its increase or stable status in the central and northern parts of the breeding areas. As a result, the world population has changed insignificantly, from 200,000-240,000 to 170,000-220,000 individuals.

Little is known about the dormouse species distribution in the Middle Volga region. The habitats of the edible dormouse Glis glis L. and the hazel dormouse Muscardinus avellanarius L. are fragmented and mainly lost in the agricultural landscape of the right Bank of the Volga River and in the coniferous forests of the right Bank of the Lower Oka River in the Nizhny Novgorod region. New data are given of features of the habitats of two sympatric dormouse species at a patch of a lime-oak forest surrounded by coniferous forests. Within the studied area, 80 wooden nestboxes were put up in places with well-connected tree canopies and well-developed understory. During three years of our study (2016-2018), preliminary data were obtained on the dynamics of nest-boxes use, relative abundance and reproduction of both dormouse species. The patch of the lime-oak forest, about 20 ha, is divided into two parts by a road and a 50 m-wide vista. Both parts did not differ in vegetation, but the edible dormouse was found in the southern part only. The hazel dormouse was found through the whole lime-oak patch, except for the woodplot no 1 (1.5 ha) occupied by edible dormice with a high density. On the basis of the data obtained, management actions are suggested to raise the level of connectivity and immigration in the population of isolated broad-leaved patches in coniferous forests, in particular, to develop a network of “key habitats”.

Comparative observations of the growth dynamics of various trees planted in the arid conditions between the Volga and the Urals were carried out taking into account the current change of natural and climatic conditions. The conditions and causes of sudden changes of the growth rates of trees were analyzed. The growth rates of adult species of the oak and the Pennsylvanian ash cultivated on clay soils, and those of the Scots pine cultivated on sandy soils were studied. The results were utilized of the previously revealed correlation between the width of annual tree rings and the hydrothermal conditions of the vegetation period, with due account of different functional significance in its annual formation of spring water recharge (precipitation in the cold season), the precipitation during the vegetation period and groundwater level, as well as the limiting influence of air temperature in the spring and summer on the gain. The possibility of a sudden change of the oak growth dynamics caused by strong long-term soil and atmospheric drought during an extremely dry year (1972) is shown, when the trees of all ranks had significantly suppressed growth not only in this year but in the next 6-7 ones. This may happen due to, for example, malfunction of the cambium or the death of a large number of lateral and absorbing roots. A significant change of the growth rates of trees during long-term annual climatogenic lowering or raising of the fresh groundwater level is shown, when the lower boundary of the root systems separates from the capillary border or saturates with moisture from it, significantly changing the moisture provision of plants. The obtained results could explain the causes of the sudden change of tree growth during studies of tree rings.

In July 2018, in the estuary area of the Sura River (a tributary of the first order of the Cheboksary reservoir, Nizhny Novgorod oblast, Russia) was record a tropical alien co-pepod Thermocyclops taihokuensis Harada, 1931 (Copepoda: Cyclopoida). Information about the discovery of this species in the European part of Russia is extremely scarce. There is only one report of the discovery of this species in the lower reaches of the Volga River. The main habitat of T. taihokuensis is distributed in East and Central Asia, as well as tropical regions. The paper presents a brief description of T. taihokuensis with updated drawings. The records in the estuarine area of the Sura River T. taihokuensis females had an average size of 1060±20 pm. The spread of tropical crustaceans beyond their natural habitat appears to be linked to human activities and the transport of ballast water by ships. In addition, the concept of zoochoria suggests that the settlement of this species may be associated with the transfer of resting stages of T. taihokuensis by migratory species of waterfowl. Thus, migration routes of various bird species from the Arctic and temperate climatic zones to subtropical and tropical regions pass over European Russia. Alien species have high phenotypic and ecological plasticity and are able to introduce ecosystems into imbalance. That is why new studies of the Sura River and the Cheboksary reservoir will help not only to judge the success of the naturalization of T. taihokuensis, but also about the environmental consequences of the penetration of this species into the territory of the European part of Russia.