Structure of poaching sturgeon species in the Irtysh River in 2013-2020 (according to ichthyologic examinations)

The study was carried out on the basis of the analysis of poaching sturgeon species in the lower reaches of the Irtysh River (the Tyumen region and Khanty-Mansi Autonomous Okrug), according to the results of forensic ichthyologic examinations over the period from 2013 to 2020. The size and weight ratio of Siberian sturgeon and sterlet in catches, the average weight of one fish species, the number of examinations performed, as well as the dynamics of these indicators for the considered time period were evaluated. As a result of the analysis performed, there has been seen an upward trend in the number of expert examinations (from 10 in 2013 to 25 in 2020). Among sturgeon species sterlet dominates in size, with the exception the period of 2017-2018. There has been stated the dynamics of increasing mass of Siberian sturgeon and, accordingly, a decrease for sterlet, with the average share of sturgeon to be less 50%. The average mass of a Siberian sturgeon species has increased from 0.8 to 1.2 kg, as well as a positive trend for the above period is noted when analyzing the total mass of sturgeon species during yearly examinations. Body mass of poached sterlet species hasn’t increased over the 8-year period, and its average value made 0.11–0.13 kg. Over the investigated period the number of forensic ichthyologic examinations has increased, the average mass growth dynamics in a Siberian sturgeon species has been stated, with predominating of immature species in both of sterlet and Siberian sturgeon catches.

The spatial and temporal variability of convective instability in the south of Western Siberia according to ERA5 reanalysis data

Представлены результаты сравнительного анализа пространственно-временной изменчивости конвективной неустойчивости на юге Западной Сибири по данным индексов неустойчивости K-Index и Total Totals, полученных из реанализа ERA5. Показано, что по значениям обоих индексов максимум конвективной неустойчивости над югом Западной Сибири приходится на Кулундинскую равнину и пойму верхнего течения р. Иртыш. Кроме того, высокие значения индексов наблюдаются над юго-востоком Урала и северо-востоком Васюганской равнины. Северная граница со значениями KIQ1 ≥ 30 ◦C и TTQ1 ≥ 50 ◦C, указывающими на вероятность образования гроз 70%, простирается до 62◦ и 61◦ с.ш. соответственно. За период 1990–2019 гг. в динамике среднегодовых значений KIQ1, в целом по территории, преобладает положительный тренд, а в динамике TTQ1 на большей части территории значимые изменения отсутствуют, однако отмечается цикличность с периодом ∼ 10 лет. A comparative analysis of the spatio-temporal variability of convective instability in the south of Western Siberia according to the K-Index and Total Totals index obtained from the ERA5 reanalysis is presented. Related to both indices, the Kulunda plain and the upper Irtysh River floodplain have the highest level of convective instability in the south of Western Siberia. In addition, high index values are observed over the southeastern Urals and the northeastern Vasyugan plain. The northern boundary extends to 62◦ and 61◦ N, respectively, with KIQ1 ≥ 30 ◦C and TTQ1 ≥ 50 ◦C, indicating a thunderstorm probability greater than 70%. The dynamics of annual average KIQ1 values for the territory as a whole are dominated by a positive trend for the period 1990–2019, and there are no significant changes in TTQ1 dynamics for most of the territory, but there is cyclicality with a period of ∼ 10 years.

Phytoplankton as an indicator of the current ecological status of the Ob River

The species composition, taxonomic structure, and the dominant complex of algae, and the distribution of phytoplankton abundance in the studied watercourse were identified based on data obtained for phytoplankton from the Ob River (from Tomsk to Salekhard) in summer 2019. Green algae (division Chlorophyta) make up the basis of the phytoplankton abundance in the river. The dominant complex is represented mainly by centric diatoms (genera Aulaсoseira, Cyclotella, Stephanodiscus) and non-heterocyst forms of cyanoprokaryotes (genus Aphanocapsa). The numbers and biomass of phytoplankton gradually decrease downstream of the Ob River; below the confluence of the Irtysh River, the edge effect occurs: increase in the diversity and density of organisms at the boundaries of ecosystems. Compared to the previous studies, the proportion of green and euglena algae, and cyanoprokaryotes in the taxonomic spectrum of phytoplankton increased, the composition of the dominant complex enriched, including due to non-heterocyst forms of cyanoprokaryotes, and the trophic status of the river increased to the category of eutrophic waters.

Migration of the Oirats in the first quarter of the 17th century on the eve of returning to Dzungaria

In 1541 the Oirats managed to form the Middle Confederation, which was led by the Khoshuts as the most powerful people. In the second half of the same XVI century the Oirats, suffering from attacks of their neighbors - the Turkic peoples from the west and south and the eastern Mongols from the east, began to move towards southern Siberia. Earlier they used to roam along the Black Irtysh river and north of the lake Zaysan, but now they began to move below the lake Yamysh. Opinions on the migration routes of the Oirats, existing in the literature, need clarification. The author offers his vision based on the archival materials and the Mongolian sources: the Hoyt Oirats, driven out of Kharakhoto by the Tumat Altan Khan, were the first to go towards the Altai Mountains. The next were the Torgut Oirats, who crossed the Altai, and then, together with the Derbets, they moved down the Irtysh river. The Elelets, the future Dzungars, left Western Mongolia for the Yenisei river sources. Already in the second decade of the 17th century the Oirats wandered along Om, Kamyshlov, Tobol and Ishim rivers, that is, they were roaming along the middle reaches of the Irtysh river. In 1623, at lake Yamysh, they defeated the troops of the Hotogoit Altyn Khan Sholoi Ubashi-Khuntaiji, but this victory did not exclude an internal struggle in the ruling house of the Khoshuts, which resulted in weakening of this people. Further civil strife forced the Torguts to move towards west, and in the early 1630s they reached the Volga river. Migrations over such long distances were possible only if there was an effective management apparatus, while maintaining traditions and identity.

Lower–Middle Pleistocene Stratigraphy of the Southern West Siberian Plain: New Data

—The Quaternary stratigraphy of the southern West Siberian Plain is considered in the context of the updated International Chronostratigraphic Scale, with the Neogene/Quarternary boundary at 2.588 Ma. New geological, lithological, paleontological, and paleomagnetic data from a reference Quaternary section in the Irtysh River valley near Isakovka Village provide more rigorous constraints on the Lower–Middle Pleistocene stratigraphy and the respective deposition conditions. The Isakovka outcrop exposes two stratigraphically expressed and paleontologically characterized units that were deposited during regional Pleistocene interglacial events of different ages: the Strunino and Serebryanoe alluvium beds lying over eroded surfaces. The species of the Corbicula genus coexisting with numerous species of Palearctic molluscs, small mammals Allophaiomys deucalion, Mimomys reidi, and last rooted lagurids Borsodia found in the Strunino alluvium are known also from continental equivalents of the warm upper Gelasian Stage in different parts of northern Eurasia. Judging by the presence of extant corbicules, the Strunino alluvium was deposited in a warm climate, with a mean annual air temperature above +16 °C and a mean winter temperature no colder than –8 °C, in rivers that remained free from ice all year round. On the basis of fauna constraints for the Serebryanoe alluvium, along with the first appearance of the European Pisidium clessini molluscs in West Siberia, the unit can be correlated with one of the earliest Middle Pleistocene interglacial events. The faunal assemblages and spore-pollen patterns of the two units indicate that the climate during the Serebryanoe deposition was slightly cooler and wetter than during the Strunino deposition, though steppe landscapes predominated on watersheds in both events. The two alluvial beds, which are traceable in river bluffs, at 30 m above the modern water level in a tectonically stable part of West Siberia, mark the hypsometrically higher position of the river network during the Early Pleistocene and early Middle Pleistocene interglacials.

Recommendations on the state of the sturgeon population of the irtysh river and its optimal extraction from the natural environment for reproduction

The results of studying the current state of the Siberian sturgeon population, clarifying the range of its distribution, the number and size-age groups in various sections of the Irtysh River are presented. Preliminary recommendations are given on the possibility of obtaining a small part of the population for the purpose of artificial reproduction. Ecological monitoring was carried out by the route-expedition method, by examining the Yertis River and the estuary areas of large flowing tributaries and reservoirs for the presence and distribution area of rare fish species. The work uses materials of research reports on the program 037 "State accounting and cadastre of fish resources" for 2004-14, data from the archives of Kazniirh LLP.When conducting research, we were guided by the provisions of Normative and methodological documentation. The research is funded by the Ministry of Ecology, Geology and Natural Resources of the Republic of Kazakhstan (Grant no. BR10264205)

MONITORING OF TRITIUM POLLUTION OF THE SHAGAN RIVER WATERS

The article presents the results of monitoring the waters of the Shagan river on the change in the specific activity of tritium for 2016–2020. The Shagan river is the longest surface watercourse on the territory of the Semipalatinsk Test Site, flowing along the eastern part of the Balapan site, where, together with the tributary, the Ashisu, flows into the “Atomic Lake”. Further, at a distance of 110 km downstream, the river forms a left-bank tributary of the Irtysh river. Previous studies have revealed and repeatedly confirmed the fact of radioactive contamination of the surface and ground waters of the Shagan river technogenic radionuclide 3H. It was revealed that the main source of pollution is groundwater entering the surface waters of the river. In this regard, in order to ensure long-term monitoring of 3H pollution of river waters, seasonal monitoring was carried out in three sections of the river located along its channel, starting from the outlet from the “Atomic Lake” heap and further downstream to the confluence with the Irtysh river.As a result of the observations, it was found that the specific activity of 3H in surface and ground waters, depending on the observation time, varies in a wide range of values. So, in the area of maximum pollution, the content of 3H changes from the minimum – 8 Bq/kg in the spring, to the maximum 370 000 Bq/kg in the summer-autumn period. At the exit points of the Shagan river outside the landfill, the concentration of 3H varies from 90 Bq/kg to 12 400 Bq/kg. In the area of the confluence of the Shagan river in Irtysh river content of 3H does not exceed 110 Bq/kg.

Landscape, Soil, Lithology, Climate and Permafrost Control on Dissolved Carbon, Major and Trace Elements in the Ob River, Western Siberia

Assuming that climate warming in the WSL will lead to a northward shift of the forest and permafrost boundaries, a “substituting space for time” approach predicts an increase in concentration of DIC and labile major and trace elements and a decrease of the transport of DOC and low soluble trace metals in the form of colloids in the main stem of the Ob River. However, an unknown factor is the change in hydrochemistry of the largest southern tributary, the Irtysh River, which is impacted by permafrost-free steppe and forest-steppe zone. Overall, seasonally-resolved transect studies of large riverine systems of western Siberia are needed to assess the hydrochemical response of this environmentally-important territory to on-going climate change.

Identification and characterization of hybrids of Acipenser ruthenus and Acipenser baerii (Actinopterygii, Acipenseriformes) from the Irtysh River

Two sturgeon species, Acipenser ruthenus (Linnaeus, 1758) and Acipenser baerii (Brandt, 1869), inhabit the Irtysh basin. In 2018, we received some “atypical” specimens of sturgeon, which were similar to A. ruthenus but had a number of pronounced external differences. The hybrids A. ruthenus × A. baerii, named “oster”, can sometimes be caught in natural habitats in the Ob and the Yenisei rivers. Despite the development of methods for the genetic identification of sturgeons, the molecular genetic characteristics of the hybrids of A. baerii and A. ruthenus have not been carried out. The purpose of this study is to develop a complex of morphological and genetic characters to identify the hybrid of A. ruthenus and A. baerii from the Irtysh River. We used a complex of morphological and genetic methods to compare the putative hybrids with parental species The putative hybrids were similar to A. ruthenus in the number of dorsal scutes, the number of rays in the dorsal and anal fins, the structure of stamens on the first gill arch, and the presence of fringe on the tendrils. The hybrids were similar to A. baerii in size and weight values, the structure of dorsal scutes, the number of lateral and ventral scutes, and the number of gill rakers on the first gill arch. Genotyping of putative hybrids by using the Inter Simple Sequence Repeat (ISSR) markers revealed the presence of sites characteristic of both parental species. The fragment of the control region of mitochondrial DNA in the hybrids matched to that of A. baerii that allowed us to identify females of A. baerii as maternal individuals of the hybrids. Possible causes and factors promoting interspecific hybridization of A. ruthenus and A. baerii were studied. This is the first described fact of the appearance of sturgeon hybrids in the Ob-Irtysh basin. It is necessary to continue monitoring studies to identify the number of these hybrids in the ecological system of the Irtysh River. The data set of morphological characters and genetic methods can be used to identify the hybrids of A. ruthenus and A. baerii.