Studied Water Area Research Articles

TAXONOMIC DIVERSITY OF BENTHIC ALGOFLORA OFF THE WESTERN COAST OF THE CRIMEAN PENINSULA

The article presents the results of the study of benthic flora along the western coast of the Crimean Peninsula (Sevastopol region, Black Sea) in the summer of 2020. Hydrobotanical studies covered the water areas of Cape Tyubek, Lukull, VaiVai, Margopulo, Nemetskaya and Yazykovaya Balka. The flora included macroalgae of 74 species from the departments Chlorophyta, Heterokontophyta and Rhodophyta. The identified taxonomic composition was characterized by high species saturation of suprageneric taxa and low genus coefficient (1.1–2.0), coincidence of the proportion “order/family” in the divisions and in the whole algoflora, as well as “order/family/genus” in Heterokontophyta and Rhodophyta. The basis of taxonomic diversity was the following Rhodophyta (Ceramiales, Corallinaceae, Rhodomelaceae, Ceramiaceae), Chlorophyta (Cladophorales, Ulvales, Cladophoraceae, Ulvaceae), Heterokontophyta (Ectocarpales, Chordariaceae). Multispecies orders and families united from 55 to 88% of the total number of species found. High species diversity was characteristic of the genera Cladophora, Ulva, Polysiphonia and Ceramium. Seventeen species included in the national Red Data Books and international lists were found in the studied areas of the western coastal zone, which indicates the conservation significance of the study area. The large proportion of permanent species, their high joint contribution with additional species, the presence of maximum occurrence in a quarter of species (100%), and the average value of Jaccard’s coefficient (60%) testified to the spatial homogeneity of the species composition in the studied water area, which corresponded to relatively uniform habitat conditions of hydrobionts along the open sea coasts. Spatial changes in taxonomic composition were moderate (Cv = 9–26%). The difference in the extreme values of the absolute number of taxa was insignificant (by 30-50%). Among the departments, Chlorophyta was characterized by the lowest variation in the number of taxa, and Rhodophyta – by the highest. The increase in the difference between the extreme values of the absolute number of taxa was realized in the direction of orders < families < genera < species. The results of phytoindication indicate the warm-water character of the flora and the emerging trend of increasing trophicity of algal habitat in the study area.

To the assessment of green sea urchin stocks in the coastal zone of the Barents Sea

The purpose of the work is to assessment the state of stocks of the green sea urchin (Strongylocentrotus droebachiensis) in the coastal zone of the Barents Sea.Methods used — to achieve the set goal, standard methods for collecting hydrobiological material and calculating the abundance and biomass of hydrobionts were used.Novelty — the data obtained as a result of the research made it possible to update information on the state of the green sea urchin stocks on the coasts of Western and Eastern Murman.Results — the total and commercial reserves of sea urchin were determined on an area of 2812 thousand m2. The total stock of sea urchins was 3.58 thousand tons, the commercial one — 2.17 thousand tons. The total density of urchins in the studied water area was 32 specimens/m², the commercial one — 10.3 specimens/m². The most promising areas for fishing have been identified.Practical significance — thanks to the use of the research results, adding them to materials from other sources, it will be possible to more accurately predict the volumes and timing of fishing. Mining companies will receive more complete information about promising fishing areas and possible catch volumes.

Assessment of the influence of abiotic environmental factors on the distribution of bream and carp in the Northern Caspian

Changing habitat conditions is an important driving force affecting the distribution of fish in the range. A quantitative assessment was made of the influence of environmental factors on the distribution of bream Abramis brama Linnaeus, 1758 and carp Cyprinus carpio Linnaeus, 1758 in the waters of the eastern part of the Northern Caspian. The number was estimated based on the results of research net catches. The preferred temperatures and habitat depths of bream and carp in the shallow zone of the Northern Caspian are shown. The colleof field material was carried out during complex expedition observations in 2014 and 2020. The installation of nets with a mesh of 30–200 mm was carried out in the shallow-water zone of the eastern part of the Northern Caspian. Bream and carp in the Northern Caspian Sea form concentrations in areas with depths up to 6–8 m. In the time interval from the end of April to October, bream was observed in the temperature range from 7.0 to 28.5 °C, carp — from 5.5 to 28.0 °C. A mathematical assessment of the influence of depth, temperature and water transparency on the number of these fish species was carried out. The obtained regression models took into account from 44.9 to 80.1% of the factors determining the number of fish in the studied water area. Carp are more sensitive to the effects of temperature, depth and transparency compared to bream. The obtained results provide a theoretical basis for predicting changes in the habitat of fish due to abiotic environmental factors, which is relevant in connection with pronounced climatic changes

Results of the Study of Resonant Oscillations in the Northern Part of the Shelf of the Peter the Great Gulf, the Sea of Japan

To study the features of resonant oscillations in the water column of the Peter the Great Gulf of the Sea of Japan, in situ measurements were carried out on its shelf, combined with numerical simulation of these processes. The observational data were obtained from autonomous bottom pressure gauges in Novik Bay in the winter of 2016. In the calculations, a spectral-difference model was used, modified to account for the ice cover, and implemented on an irregular triangular grid. The atmospheric forcing used in the model had periods from 15 to 55 min. As a result, characteristic series of spatio-temporal parameters for resonant oscillations of the studied water area were determined. The locations of the peaks on the simulated resonance curves correspond to the locations of well-defined maxima of the energy spectrum according to in situ measurements, hence indicating the possibility of a significant resonant amplification of level fluctuations by wave and periodic wind effects. The novelty of this study is inclusion of the winter period, when the surface of the bay is partially covered with ice.

ПАЛЕОБИОГЕОГРАФИЧЕСКИЕ РЕКОНСТРУКЦИИ ДЛЯ КОНЦА ПОЗДНЕГО КАМПАНА ПО ПЛАНКТОННЫМ ФОРАМИНИФЕРАМ В ТИХОМ ОКЕАНЕ

The paper considers the results of the analysis of the taxonomic composition of planktonic foraminifera (PF) from the end of the Late Campanian in the Pacific Ocean. To identify the latitudinal-zonal faunas of the PF, an assessment was made of the species similarity and differences of the PF complexes of the same age from different wells. Based on the difference in species composition, the fauna of the PF is divided into non-arctic regional and oceanic latitudinal-zonal: subtropical western, tropical central and subtropical central oceanic faunas. To reconstruct the climatic fluctuations that occurred at the end of the Campanian century in the Pacific Ocean, the systematic composition of the shells of planktonic foraminifera was studied from the core samples of eleven deep-sea drilling wells.The identified PF thanatocenoses were assigned to two types (Tethyan, intermediate) and one subtype (thermal-boreal). Based on the spatial distribution of thanatocenoses, the position of climatic zones for two sections of the late Campanian was determined. Within the studied water area, two climatic zones were developed during the studied age interval: intermediate and Tethyan. In the middle of the Late Campanian, the boundary between them passed in the paleoequator region. At the end of the late Campanian, it became sharply colder. The intermediate and Tethyan zones narrowed. In the northern part of the studied water area, a warm-boreal subzone was revealed, in the southern part, the Tethyan subzone was replaced by an intermediate zone. The obtained reconstructions are confirmed by our own and published data of oxygen isotope analysis.

The current ecological and ichthyotoxicological state of the Svir bay of Lake Ladoga

A significant part of the water area of the bay is represented by a shallow littoral, which is characterized by the highest biodiversity and bioproductivity. Approximately 90% of benthic organisms known for Lake Ladoga are inhabitants of the littoral zone. The littoral and water areas gravitating towards it are a spawning and feeding place for all fish species living in the lake. The Svir Bay of Lake Ladoga is located in the southeastern part of the lake water area. Its area is 260 km2. The present study in the water area of the Svirskaya Bay with an assessment of the state of the ichthyofauna was carried out in the summer of 2022, and the previous one - in the eighties of the last century The article presents the materials of biological and chemical-analytical studies in the Svir bay of Lake Ladoga, which is of great fishery importance. The ecological and ichthyotoxicological state of the studied water area and the most important importance of the ichthyofauna in assessing the state of its individual sites are shown. Thus, the shallow littoral zone turned out to be more polluted compared to the more remote from the coast and more deepened southern part of the lake. A higher level of pollution of the littoral, which occupies a significant part of its water area, negatively affected the ichthyofauna of the reservoir and its reproduction, which led to an impact on fish stocks, especially valuable species, and the structure of the ichthyocenosis of the lake as a whole. The results of the research also showed that the condition of the lip as a whole has improved somewhat compared to the eighties of the last century, when the last ichthyotoxicological studies were conducted in this water area. Taking into account the state of the ichthyofauna and other indicators of the study, the pollution level of the Svir Bay of Lake Ladoga can be characterized as weakly expressed sublethal.

Характеристика прибрежной ихтиофауны губ Восточного Мурмана в летний период 2020 года

In the article was considered species composition of fish in the littoral and sublittoral zones of Yarnyshnaya and Zelenetskaya bays (Barents Sea) during summer 2020. For the first time, the kelp snailfish Liparis tunicatus was recorded in the studied water area. At whole was discovered 15 species of fish and most abundent between them is staghorn sculpin Gymnocanthus tricuspis and shorthorn sculpin Myoxocephalus scorpius. Also quantitative characteristics of the distribution for each fish species are represented. The dynamics of abundance and diversity of coastal fish communities were analyzed. Comparing of perennial data with 2020 indicates that at the present observed relatively rich species composition, low fish distribution density, low abundance of young Gadidae, but high indicators of biodiversity in coastal communities.

Оценка состава водных масс восточной части Баренцева моря с использованием современных данных о параметрах δ18O и δ2Н

This paper presents the results of measurements of δ18O and δ2H stable isotope values in the waters of the Barents Sea, which were carried out in March–April 2021. Based on the data presented, the ratio of base water content – atlantic (fa), river (fr) and melt water (fi), as well as the volume of water withdrawn for ice formation in the studied water area was assessed. The comparative estimation of base water content, calculated on values “δ18O–salinity” and “δ2H–salinity” is presented and obtained values do not exceed limits of mean value ±sd. However, average values of Atlantic and ice water content calculated using δ2H parameter are higher than those using δ18O, and river water content is lower. The use of δ18O and δ2H parameters in oceanographic studies in the calculation of balance characteristics is preferable to temperature and salinity because of their greater conservativity.

The current ecological and ichthyotoxicological state of the shlis-selburg bay lake Ladoga

The article presents the materials of biological and chemical-analytical studies of the Shlisselburg Bay of Ladoga lake, that plays an important fishery and sanitary-hygienic role as a source of water supply of St. Petersburg. The dominant role of ichthyo-fauna in the assay of the ecological and toxicological state of the studied water area is shown. The purpose of the conducted research is to assess the ecological and ichthyo - toxicological state of the Shlisselburg Bay of Ladoga lake, as one of the main fishery water areal and the only source of water supply of St. Petersburg (the source of the Neva River). Biological and chemical analytical studies of the water area of the Shlisselburg Bay in laboratory conditions were carried out in the summer-autumn period in 2022 in three water areas. A feature of the Shlisselburg Bay is the presence of a runoff flow, that initiates the removal of pollutants and the nature of bottom sediments, which makes the Bay less vulnerable to anthropogenic impact. Currently, the methods used to assess water quality for the fisheries perspective are biological – bioindication and biotesting, as well as the results of chemical analysis in comparison with the standards for the content of harmful substances in water, sediments, precipitation and fish. Preference is given to “express’ methods: biotesting and bioindication of fish research results. Analysis of materials from previous studies have given reason to consider a gradual decrease in anthropogenic load (exposure to pollutants) on fish, as generally recognized indicators of water quality, given from fisheries positions. The results of the research showed that the ecological and toxicological condition of the Shlisselburg Bay has now improved, but cannot be considered satisfactory. Taking into acount the state of the ichthyo fauna and the level of its pollution, it can be characterized as weakly expressed sublethal with a possible transition to medium-expressed, conditionally sublethal in the spring period.

Assessment of contamination of marine sediments and their potential toxicity in the Uglovoy Bay, Peter the Great Gulf, Sea of Japan/East Sea.

The content of harmful heavy metals in the bottom sediments of the Uglovoy Bay (Peter the Great Gulf, Sea of Japan/East Sea) was studied based on the surveys carried out in 2016-2021. The contamination of the sediments in the bay was compared to the background concentrations of elements and to common contamination indices. The degree of contamination was calculated using the contamination factor (Cf), modified overall degree of contamination (mCd), and index of geoaccumulation (Igeo). The toxicity of marine sediment samples for each metal was evaluated using the threshold effect level/probable effect level (TEL/PEL) values and the sediment quality guideline quotient (SQG-Q). The sources of pollutants entering the studied water area were analyzed. It is shown that the contamination of the Uglovoy Bay occurs continuously as a result of economic activities on its coast. The dynamics of contamination of the bay for the period 2016-2021 is presented.

Evaluation of Suspended Matter Content in the Coastal Zone of the Northeastern Part of the Black Sea by Relative Transparency

Based on the materials of 20 expeditions of the IO RAS conducted in various areas of the coastal zone of the Russian sector of the Black Sea in the period from 1999 to 2021, empirical equations the relationship between the relative transparency (depth of visibility of the white disk Zd) and the mass concentrations of the total suspended matter-SM and its mineral – SMM and organic – POM fractions (Csm, Csmm and Csom, respectively) were obtained. The values of Zd were recorded in the range from 0.1 to 21 m, the concentrations of SMM – from 0.11 to 104 mg/L, POM – from 0.09 to 2.0 mg/l and chlorophyll a (Ca) – from 0.03 to 4.4 mcg/l. The relative abundance of the POM in the suspension ranged from 1.1 to 48.7%. The estimation of the error in the calculations according to these equations is carried out. The coefficients of determination r2 = 0.85 (for lgCsm and lgCsmm ) and 0.72 ( for lg Csom). The influence of the concentration of POM – on the accuracy of the calculation of Csmm and the concentration of chlorophyll a on the accuracy of the calculation of Csom was revealed. It is concluded that it is possible to use empirical formulas related to the entire array to calculate the concentrations of these fractions of suspension in the entire studied water area. It is proposed to consider the method of estimating the content of suspension fractions based on the obtained empirical equations as a regional variant of the method of passive sounding of the upper layer of the sea using a white disk.

Composition and structure of diatoms in the zone of influence of the Nizhny Novgorod hydroelectric station

During the present research, the analysis of the floristic composition and structural indicators of the diatoms in the Volga river’s phytoplankton in the zone of influence of the Nizhny Novgorod hydroelectric station in the growing season of 2022 was performed. In the list of algoflora of the studied water area, diatoms occupied the third place, giving way to green and blue-green algae, and numbering 55 species and intraspecific taxa. The dominance of diatoms was observed in May and October due to the contribution of colonial centric diatoms. The presence of invasive brackish–water species - Thalassiosira incerta I.V. Makarova, Skeletonema subsalsum (A. Cleve) Bethge is noted.

Role of glacial and lithodynamic factors in the formation of the sedimentary cover structure of the Great Salma Strait (White sea)

New data on the bottom relief in the waters adjacent to the Belomorskaya Biological Station of Moscow State University (Kandalaksha Bay), obtained with the help of a multipath echo sounder (MBE), allowed us to study the bottom relief in detail and clarify the structure of Quaternary sediments in this area, significantly detailing the previously obtained data of continuous seismoacoustic profi ling (CSP). In the western part of the studied water area, the de Geer moraines were first identifi ed in a complex of glacial deposits, which were formed during the retreat of the glacier in the late Pleistocene in an easterly direction towards the modern deep-water part of the White Sea. In the deep-water part of the water area, according to the data of the MBE and CSP, sediments were studied, the genesis of which is due to the intensive manifestation of gravitational processes at the end of the Late Pleistocene — Holocene. The new data obtained may indicate the existence of “dead” ice in the Belomorskaya Depression.

Field studies of bioluminescence in Bransfield Strait in 2022.

In January 2022, during scientific cruise 87 on the RV Academic Mstislav Keldysh in the Atlantic sector of the Southern Ocean, three hydrobiophysical cross-sections were performed in the Bransfield Strait. Bioluminescent signals were measured in a layer of 0-200 m at each of the 24 stations located at three sites. For the first time, a new hydrobiological system 'Salpa MA +' was used, which made it possible to obtain novel data in the photic layer of the studied water area. Bioluminescence studies were accompanied by simultaneous measurements of background indicators: temperature, electrical conductivity, photosynthetically active radiation, and they were compared with the data from plankton samples processing. Bioluminescent potential was registered at almost all the stations. The maximum level of bioluminescence was registered in the area of the archipelago of the South Shetland Islands, where the maximum accumulation of Salpa thompsoni, Foxton 1861 was noted. The purpose of this work is to identify the main factors and patterns affecting the intensity of the bioluminescence field in the region under study.

Study of Free Oscillations of Bays in the Northwestern Part of Posyet Bay

To study the specific features of free surface oscillations in the northwestern part of Posyet Bay (the Sea of Japan), a series of experimental works using an installation with a laser meter for measuring hydrosphere pressure variations were carried out in 2012 and 2014. In the course of the joint analysis, measurement results for oscillations with periods of 10–30 min and the results of calculations using a numerical model of shallow water with a difference approximation on an irregular triangular space grid, datasets of the space–time parameters for the resonance oscillations of the studied water area were obtained. The results of the numerical simulations confirm the manifestation of the resonance properties of Novgorodskaya, Expedicii, and Reyd Pallada Bays water areas on the oscillations singled out during the experimental studies. The positions of the peaks on the model resonance curves are consistent with the positions of the clearly pronounced peaks of the energy spectrum in the field data.

ВЛИЯНИЕ АНОМАЛЬНО ВЫСОКОЙ ТЕМПЕРАТУРЫ ВОДЫ НА ГИДРОХИМИЧЕСКИЙ РЕЖИМ УСТЬЕВОЙ ОБЛАСТИ МАЛОЙ РЕКИ (НА ПРИМЕРЕ ПРИТОКА РЫБИНСКОГО ВОДОХРАНИЛИЩА)

The increase in water temperature in the summer of 2010 affected the change in some hydrochemical characteristics in the water of the mouth area of the river. Ild, a tributary of the Rybinsk Reservoir. The maximum water temperature in the studied area was recorded in May and the second half of summer 2010. A high significant correlation between temperature and organic matter indicators was noted. During the period of maximum warming up in 2010, the total amount of organic matter, its labile fraction, and suspended solids were significantly higher than the period close to the long-term average. A large amount of atmospheric precipitation in June 2010 determined the maximum concentrations of OM, total and dissolved iron. The organic matter is represented mainly by freshly formed compounds, the suspended form of iron prevails over the dissolved one. The organic nature of iron in water is evidenced by a significant correlation between iron and OM in both years studied, r = 0.89–1.0, p <0.05. At the same time, temperature anomalies did not affect the content of dissolved oxygen and an increase in water salinity. The macrocomponent chemical composition of the water in the studied areas is dominated by hydrocarbonate ions, calcium and magnesium ions. In 2009, the relative content of HCO3 and Mg from the section of the free flow of the river to the reservoir is higher than in 2010. At the same time, the relative content of SO4, Cl, and Ca ions, on the contrary, is lower. From spring to autumn, a tendency towards a decrease in the relative content of HCO3 in both studied years was noted in the entire studied water area. The content of hypothetical salts NaHCO3 and MgHCO3 in 2009 exceeded those in 2010 by 3.4 and 5.0 times, respectively. In zones I – IIc, the content of calcium ions is 1.5–2.0 times higher than that of magnesium in 2009, and in 2010, 1.7–2.4 times. In the deep-water section of the reservoir in both years under study, the concentration of calcium ions is, on average, 2 times higher than that of magnesium. In both studied years, the potassium content in the studied water area is noticeably lower than the sodium content. During the spring flood, the K/Na ratio reaches its maximum values (up to 0.58). R. Ild is located in a zone of excessive moisture and is characterized by good soil leaching, especially from readily soluble salts (sulfates and chlorides), groundwater has extremely low concentrations of sulfates (less than 2 mg/dm3) and chlorides (2–4 mg/dm3). In 2009, the concentration of chlorides in the water of the studied water area does not exceed 8.0 mg/dm3 on average, in 2010 – 13.0 mg/dm3. In the place of mixing of river and reservoir waters, a decrease in the content of chlorides in water by dilution is observed. The concentration of sulfates in the water of the studied water area in 2009 averaged 3.6–13.3 mg/dm3, in 2010 – 3.6–22.9 mg/dm3. Due to the active biogenic absorption of sulfates, their minimum concentrations are inherent in the summer low-water period in both studied years. The content of hypothetical salts also shows that the amount of MgSO4 in June–July is less than in other periods.

Development of algorithms for assessing risks and vulnerability to anthropogenic impacts

The paper presents currently used approaches to the assessment of water pollution by various types of pollutants. Based on the existing criteria, an algorithm for assessing risks and vulnerability to anthropogenic impacts is proposed. The software package obtained on their basis makes it possible to model the processes of the spread of pollutants in the studied water area, to detect and evaluate the power of sources of pollutants and manage them, to assess risks and vulnerabilities in relation to anthropogenic impacts, to carry out zoning of the water area of a shallow water body in accordance with the levels of anthropogenic loads, to carry out environmental design from the standpoint of sustainable development.

Influence of fish farming on the chemical composition of Lake Veljo water in 2015-2021

Lake Velie is one of the largest reservoirs in the Novgorod region. It is part of the Valdai National Park and is located on the Valdai Moraine Ridge. However, environmental risks caused by pollution of the aquatic environment in areas where commercial aquaculture is grown, as well as the negative impact of fishery activities on the environment, can become an obstacle to further use of the lake water area for fishery purposes. Summarizing the data obtained, we can state the following: within a radius of 100 meters from the cages, the chemical composition of the water in the column is practically the same as in the central part of the lake.The dispersion of the introduced substance obtained, both empirically and experimentally, corresponds to 50 m. At a distance of 50 m from the cages, water quality class 3 (moderately polluted). However, in a 10-meter zone, the water acquires the characteristic contaminated. In this part of the studied water area, the normative indicators for the content of biogenic substances on the surface and at the bottom are exceeded, and in the near -bottom horizon the numerical indicators are slightly higher than at the surface. This is most likely due to the accumulation of excessively introduced artificial feeds in the bottom horizon. Even with a favorable temperature and oxygen regime of the reservoir, such a situation does not contribute to the cultivation of healthy marketable fish. And the lack of comprehensive monitoring studies may leave unnoticed the prerequisites for the deterioration of water quality in Lake Velje.

Meander reshaping – the formation process of a wintering riverbed depression of fish

The study of the spatiotemporal distribution of fish is an important and poorly studied aspect of the ecology of aquatic organisms. The research work was performed using the modern hydroacoustic method and geographic information systems. A section in the lower reaches of the Irtysh, a large transboundary Siberian river (in Western Siberia, Russian Federation), was studied. It has a strong development of meandering. The merging (i.e., reshaping of closely spaced meanders and erosion-accumulating channel processes) results in development of wintering riverbed depression, which is a critical “temporal bottleneck” during the winter period of the fish life cycle. The average density of fish in the study area in summer and autumn was 8,031 and 9,194 individuals per ha, respectively. Analysis of the distribution of fish showed that the distribution in the horizontal aspect had a more aggregated character in the autumn. In the vertical aspect, it had a more surface (pelagic) character. The ichthyofauna in the water area of the riverbed depression is mainly represented by cyprinids. The loop-shaped evolution of the channel formed a section of the river with multidirectional, circulating, and counter-current flows. It also created zones with depths exceeding 20 m and aggregations of fish. These features characterize the studied water area as a wintering riverbed depression of the fish of the Lower Irtysh. This section of the river should be included in the list of protected wintering biotopes of fish in the West Siberian fishery basin, which will ensure the conservation of fish at the critical stage of the life cycle.

Meander reshaping – the formation process of a wintering riverbed depression of fish

The study of the spatiotemporal distribution of fish is an important and poorly studied aspect of the ecology of aquatic organisms. The research work was performed using the modern hydroacoustic method and geographic information systems. A section in the lower reaches of the Irtysh, a large transboundary Siberian river (in Western Siberia, Russian Federation), was studied. It has a strong development of meandering. The merging (i.e., reshaping of closely spaced meanders and erosion-accumulating channel processes) results in development of wintering riverbed depression, which is a critical “temporal bottleneck” during the winter period of the fish life cycle. The average density of fish in the study area in summer and autumn was 8,031 and 9,194 individuals per ha, respectively. Analysis of the distribution of fish showed that the distribution in the horizontal aspect had a more aggregated character in the autumn. In the vertical aspect, it had a more surface (pelagic) character. The ichthyofauna in the water area of the riverbed depression is mainly represented by cyprinids. The loop-shaped evolution of the channel formed a section of the river with multidirectional, circulating, and counter-current flows. It also created zones with depths exceeding 20 m and aggregations of fish. These features characterize the studied water area as a wintering riverbed depression of the fish of the Lower Irtysh. This section of the river should be included in the list of protected wintering biotopes of fish in the West Siberian fishery basin, which will ensure the conservation of fish at the critical stage of the life cycle.