Volume 50, Nº 1 (2019)

We have studied the upper layer of a peat deposit that was formed in the gradient of a gas flare impact on an oligotrophic bog in Western Siberia more than 20 years ago. Changes in the temperature parameters of surface air and the rooting peat horizon, as well as an increase in the degree of decomposition and ash content, a decrease in the bog water level and acidity of the upper layer of the peat deposit in the impact zone of flare, have been recorded. The relationship of changes in the hydrological and temperature regimens with changes in the peat composition and properties is shown. The botanical and spore-and-pollen analyses have revealed a trend in the reciprocal development of the upper horizon of the oligotrophic peat deposit towards eutrophication: the change in the fuscum peat for moss–dwarf-shrub peat.

The present study was conducted to investigate the n-alkane composition of typical alpine meadows. Plant and soil samples were collected and analyzed to characterize the n-alkane components. The results show that the n-alkane with maximum concentration (C_max) was C₂₂ in Ligularia virgaurea and Aconitum pendulum, C₂₉ in Elsholtzia densa, Pedicularis kansuensis and Oxytropis kansuensis, and C₃₁ in Potentilla anserine and Leontopodium nanum. Furthermore, the C₂₉ and C₃₁ concentrations in the surface soil from typical alpine meadow were higher than that in sub-layer soil; however, the opposite relationship was seen in soil from degraded alpine meadow. In addition, the correlation between the long chain n-alkanes in soils and plants was strongly significant (p < 0.01, r = 0.816). The change of the C₂₉ and C₃₁ concentration with soil depth could be related to the plant succession of the alpine meadow.

Parameters of hematopoietic tissue and peripheral blood in the Caucasian snow vole (Chionomys gud Satunin, 1909), a typical mountain species of small mammals, have been studied for the first time along a latitudinal–longitudinal (rather than altitudinal) gradient. It has been found that the blood of snow voles living at the same elevation (1800 m a.s.l.) in the maritime climate of the Western Caucasus and in the continental climate of the Central Caucasus has similar oxygen-carrying capacity, but this is provided by different mechanisms. The results of this study suggest that the natural conditions of the Western Caucasus are most optimal for the species.

It has been shown that the main drivers of the dynamics of cladoceran and copepod abundances can be predators (fish), the quantity and/or quality of food in terms of the contents of eicosapentaenoic acid, phosphorus and nitrogen in the seston under eutrophic conditions. In experimental mesocosms under eutrophic conditions, we found that, fish did not affect the quantity and quality of food resources for crustaceans. In the second half of experiments, however, dominance shifted from copepods to cladocerans. This was due to the improvement of the food quality for cladocerans in terms of the carbon-to-phosphorus ratio in the seston rather than to fish predation. Under eutrophic conditions, fish reduced the biomass of both cladocerans and copepods without changing the ratio between them.

The study of macrozoobenthos in the Middle and Lower Volga reservoirs has revealed stable cenotic complexes of Ponto-Caspian and Ponto-Azovian species, which are characterized by consortium interactions. It has been shown that the leading environment-forming role in bottom communities is played by dominant mollusk species: Dreissena polymorpha (Pallas, 1771) and D. bugensis (Andrusov, 1897). Patterns of the formation of interconnected pairs of species in the Ponto-Caspian and Ponto-Azovian complexes in waterbodies of different types are analyzed.

There are increasing evidences documenting the negative impact of exotic species including mosquitofish, Gambosi affinis, in Iran. Meanwhile, recent climate change in freshwater ecosystems in arid and semi-arid regions such as Iran is expected to cause undesirable impact. We conducted experiments in 2 levels of temperature and predator density including: high temperature/high predator (HT/HP), high temperature/ low predator (HT/LP), low temperature/high predator (LT/HP), and low temperature/low predator (LT/LP) that carried out within 20 days. Larval growth rate was highest at the HT/HP (0.29 mm/day), development stage was slowest at the LT/HP treatment (Gosner: 28.33 ± 0.33), and survival rate was lowest at HT/HP treatment (0.00%). Except for the significant impact of predator density on survival, B. variabilis was tolerant of both predator density and increased temperature and there was no interaction between predator density and increased temperature in term of growth, development and survival. But, combined effects of temperature and predator density showed significant effects on growth, metamorphosis, and survival over time.

The gray crow stay at the Polar circle latitude in Western Siberia lasts approximately six months, from the beginning and middle of April to the beginning and middle of October. The timing of the arrival of the gray crow to the Lower Ob region shifted to earlier calendar dates from 1970–2017. The breeding season starts in May and lasts 2.5–3 months, until late July. Postbreeding moulting starts in June and is combined with the feeding of chicks, with an ending in September. The postjuvenile moulting starts at the age of 50–55 days, in August; it lasts 2.5–3 months until the middle and end of October and is combined with migration. The departure for wintering takes place in September and the first half of October. One-year-old birds stay in the wintering area in the basins of the Kama and Volga Rivers until March–April and return to the hatching region in April–May. The space of the East European Plain is the area where crows of the northern, northeastern, and eastern populations are concentrated in winter, replacing the nomadic and migratory areas of local populations.