The role of anthropogenic impact and natural habitat conditions in the reproduction of semi-passable and mass river fish of the lower reaches of the Volga River according to retrospective data

2021 ◽  
pp. 34-46
Author(s):  
Natalia Ivanovna Chavychalova ◽  
Dina Germanovna Taradina ◽  
O.M. Vasilchenko ◽  
Raigul Sadyakhovna Mukhanova
Keyword(s):  
Water Content ◽  
River Flow ◽  
Juvenile Fish ◽  
Natural Habitat ◽  
Hydrological Regime ◽  
High Water ◽  
Food Competition ◽  
Volga River ◽  
Spawning Grounds ◽  
River Fish

A retrospective review of the main factors that caused the decline in the reproduction of semi-passable fish in the lower reaches of the Volga River is given. Long-term data on the yield of juvenile semi-passable and river fish are presented, on the basis of which the current state of natural reproduction of roach, carp is estimated as low; bream, bluefin and perch — satisfactory; crucian carp, gaster and rudd — safe. Overregulation of the Volga River flow near Volgograd violated the natural conjugacy of water and temperature regimes. In the regulated period, the timing of the onset of spawning temperature in most cases is ahead of the flooding of the strips. The lag of the delta spawning grounds begins when the runoff is less than 120 km³ and reaches the maximum values (up to 27 days) in years with extremely low water content. The delay in flooding of spawning grounds in conditions of unsatisfactory water content leads to the accumulation of producers in limited areas of strips and simultaneous spawning of fish with different ecology. This leads to increased food competition of the larvae and reduced survival. After the flow was regulated, the rates of rise and fall of the hollow waters increased by 2 times, the hatching of the larvae, as a rule, coincided with the onset of the flow of the hollow waters. The mass removal of larvae into the delta watercourses at the early stages of ontogenesis, due to their lack of viability in river conditions, leads to a decrease in the productivity of spawning grounds. In the modern period (2003– 2019), due to the predominance of unfavorable hydrological regime, the duration of high water and flooding of the poloi years, and in order to clarify the yield of juvenile fish in the lower reaches of the Volga, its accounting was carried out not only in the poloi of the delta, but also in the coastal watercourses (where a large number of larvae and fry that rolled off the poloi and from local spawning), in the kultuch zone and on the poloi of the lower zone of the Volga-Akhtuba floodplain.

Dependence of efficiency of natural fish reproduction in water bodies of Kazakhstan from water level

2021 ◽  
pp. 32-41
Author(s):  
K.B. Isbekov ◽  
E.V. Kulikov ◽  
S.Zh. Asylbekova
Keyword(s):  
Water Content ◽  
Water Regime ◽  
Juvenile Fish ◽  
Hydrological Regime ◽  
Water Bodies ◽  
Fish Reproduction ◽  
Data Set ◽  
Commercial Fish ◽  
Level Of Significance ◽  
The Impact

The article deals with the relationship between the hydrological regime of water bodies and the efficiency of fish reproduction. The hydrological regime of water bodies in years of different water content influences the reproduction and, accordingly, the quantitative and qualitative composition of ichthyocenoses. The easiest way to assess the efficiency of fish reproduction is by such an indicator as the productivity of juveniles, i.e. the number of juvenile fish per unit area or volume. The material for this work was carried out in large fishing reservoirs of the Republic of Kazakhstan in the process of fishery research (2013–2018). Comparison of hydrological parameters and productivity of juveniles by years shows their relationship. Correlation coefficient between water content (runoff) of the river Zhaiyk and juvenile yield +0.73 (data set for 11 years, reliable for the level of significance p = 0.01). The yield of juvenile fish from Lake Balkhash has a high correlative dependence on the inflow of water into the lake (r = +0.826) (massif 2013–2018, reliable for the level of significance p = 0.05). Correlation analysis showed that the productivity of juvenile fish in the Kapshagai reservoir has an average degree of dependence on water content (average annual level) (r = +0.641, reliable for the level of significance p = 0.05). Regular relationships between the water regime and the efficiency of reproduction (productivity of juveniles) of fish have been established. The efficiency of natural reproduction of commercial fish species in modern conditions of the water regime, water withdrawal for economic needs and the impact of fishing is significantly reduced, but with the implementation of the reclamation measures proposed in the work, its partial restoration is possible.

scholarly journals The Change of the Water Regime of the Volga River in the Area of the Protected Island Bakhilovsky

2020 ◽  
Author(s):  
Keyword(s):  
Water Content ◽  
Water Regime ◽  
High Water ◽  
Ecological State ◽  
Spring Flood ◽  
Volga River ◽  
High Water Period ◽  
Average Water ◽  
Annual Water

The ecological state of the protected Islands Seredysh and Shalyga (now Bakhilovsky island) depends on the water content and flow of the Volga River. We have analyzed the long-term changes in the water flow of the Volga River for the period 1958-2017 in the alignment Zhiguli dam, located 12 km upstream from the island. According to the average annual water consumption, there are three periods that differ from each other in water content: low-water period (1958–1976), high-water period (1977–1997) and the period of average water content (1998–2017), with extremely low-water (1967, 1973, 1975, 1976, 1977, 1996) and extremely high-water (1966, 1979, 1981, 1990, 1991, 1994) years. In highwater years, during the passage of the spring flood, the island is almost completely flooded, and in low-water years, during the summer low water, the area of the island increases and changes its configuration.

EFFICIENCY OF SEMI-ANADROMOUS AND RIVER FISHES’ REPRODUCTION IN DIFFERENT WATER MODES OF THE VOLGA RIVER

Fisheries ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 67-73
Author(s):  
Natalya Chavychalova
Keyword(s):  
Hydrological Regime ◽  
Biological Indicators ◽  
Volga River ◽  
Feeding Duration ◽  
Natural Reproduction ◽  
Runoff Regulation ◽  
Fish Spawning ◽  
Commercial Species ◽  
Efficiency Of Reproduction ◽  
River Fish

The paper shows the efficiency of natural reproduction of semi-anadromous fish, including the main commercial species such as roach and bream, and river fish species depending on the volume, hydrological regime and duration of spring flood, and the temperature regime of the Volga river during fish spawning. A comparative assessment of the conditions and results of roach and bream reproduction in different water years and periods of Volga runoff regulation is given. The dependence between feeding duration of semi-anadromous and river fry and the efficiency of reproduction, the number of viable younglings and their biological indicators in different water years is shown.

scholarly journals INFLUENCE OF RUNOFF AND FLOOD REGIME ON QUALITY CHARACTERISTICS OF BREAM JUVENILES (ABRAMIS BRAMA ORIENTALIS L.) IN THE EASTERN AND WESTERN PARTS OF THE VOLGA DELTA

2019 ◽  
pp. 22-32
Author(s):  
Natalia Ivanovna Chavychalova ◽  
Sergey Vladimirovich Ponomarev ◽  
Olga Mikhailovna Vasilchenko
Keyword(s):  
Age Distribution ◽  
High Water ◽  
Middle Zone ◽  
Volga River ◽  
Spawning Grounds ◽  
Volga Delta ◽  
Stage Of Development ◽  
Natural Reproduction ◽  
Spawning Periods ◽  
Qualitative Characteristics

The paper presents the assessment results of the influence of hydrological conditions on the qualitative characteristics of bream juveniles in the Volga delta. The influence of factors (volume, hydrological characteristics of spring flood, temperature conditions) on the spawning periods of producers, duration of feeding of juveniles at spawning grounds, including viable ones, at the end of the hollow period has been traced. There have been presented the comparative data on the age, distribution and qualitative composition of larvae and juveniles obtained in the course of the research works at spawning grounds in different regions of the lower reaches of the Volga River in 2011-2017. The most favorable conditions for feeding on young bream have been found to form in the high-water years (2013 and 2016) and in the mid-water year (2017). Years 2011 and 2015 became critical for natural reproduction; years 2012 and 2014 were unfavorable. The highest size-weight characteristics of bream juveniles were observed by the end of the hollow period in the east of the delta in the arid and middle water years, and in high-water years they were found in the Volga-Akhtuba floodplain. The qualitative characteristics of bream in the east in low-water years were maximum in the upper zone, minimal - in the middle zone, in the western spawning grounds there was observed a reverse situation. In high-water years the highest values of bream juvenile size-weight parameters were observed in the middle zone in the east of the delta. In the mid-water year (2017) in the eastern part of the delta the maximum feeding results were observed in the lower zone, and in the spawning grounds of the western delta - in the middle zone. By the end of the feeding period in high-water years practically all bream juveniles (98.4%) reached the viable stage of development, and in arid years only 28.4% of bream juveniles reached the stage.

CRITICAL FACTORS OF WATER CONTENT FOR FISH STOCKS IN THE WATER RESERVOIRS OF KAZAKHSTAN

2017 ◽  
pp. 9-18
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Evgeniy Vyacheslavovich Kulikov
Keyword(s):  
Water Content ◽  
Water Level ◽  
Water Availability ◽  
Hydrological Regime ◽  
Fishing Effort ◽  
Water Reservoirs ◽  
The Caspian Sea ◽  
Annual Fish ◽  
Commercial Fish ◽  
Fish Stocks

The hydrological regime of water reservoirs in different years has a decisive impact on the abundance of commercial fish stocks and the quality of ichthyocenoses. In this connection in 2015-2016 there was conducted a retrospective analysis and ranking of hydrological regime impact on these factors. The paper gives evaluation of catches and fish stocks under different scenarios of water availability in the main fishing ponds of the Republic of Kazakhstan that give about 80% of the annual fish catch of the country (except the Caspian Sea). There were analyzed 2000 factors of hydrological regime (water level, annual discharge) and 1845 factors of fishing stocks (catches, abundance, fish biomass). The paper determines the critical characteristics of water availability for fish stocks. There have been proposed a number of administrative decisions and actions in case if water content would approach to the critical level. Among them: limitation of fish catches in the following year; widening zones restricted for fishing; intensification of safety measures of the fish young in residual ponds during arid periods; introduction of catch standards for a unit of fishing effort in low-water years, high-water years and years with normal water level in rivers.

Hydrogels as Antibacterial Biomaterials

2018 ◽  
Vol 24 (8) ◽  
pp. 843-854 ◽  
Author(s):  
Weiguo Xu ◽  
Shujun Dong ◽  
Yuping Han ◽  
Shuqiang Li ◽  
Yang Liu
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Tissue Engineering ◽  
Water Content ◽  
Oxygen Permeability ◽  
Structural Diversity ◽  
High Water ◽  
Clinical Applications ◽  
High Water Content ◽  
Biomedical Field

Hydrogels, as a class of materials for tissue engineering and drug delivery, have high water content and solid-like mechanical properties. Currently, hydrogels with an antibacterial function are a research hotspot in biomedical field. Many advanced antibacterial hydrogels have been developed, each possessing unique qualities, namely high water swellability, high oxygen permeability, improved biocompatibility, ease of loading and releasing drugs and structural diversity. In this article, an overview is provided on the preparation and applications of various antibacterial hydrogels. Furthermore, the prospects in biomedical researches and clinical applications are predicted.

Microwave-Induced Thermoacoustic Imaging for Embedded Explosives Detection in High-Water Content Medium

2019 ◽  
Vol 67 (7) ◽  
pp. 4803-4810 ◽  
Author(s):  
Xiong Wang ◽  
Tao Qin ◽  
Yexian Qin ◽  
Ahmed H. Abdelrahman ◽  
Russell S. Witte ◽  
...  
Keyword(s):  
Water Content ◽  
High Water ◽  
Explosives Detection ◽  
High Water Content ◽  
Thermoacoustic Imaging

scholarly journals Deep mantle melting, global water circulation and its implications for the stability of the ocean mass

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Shun-ichiro Karato ◽  
Bijaya Karki ◽  
Jeffrey Park
Keyword(s):  
Phase Transformation ◽  
Water Content ◽  
Sea Level ◽  
High Water ◽  
Water Circulation ◽  
Mantle Melting ◽  
High Water Content ◽  
Mineral Physics ◽  
Deep Mantle ◽  
Global Water

AbstractOceans on Earth are present as a result of dynamic equilibrium between degassing and regassing through the interaction with Earth’s interior. We review mineral physics, geophysical, and geochemical studies related to the global water circulation and conclude that the water content has a peak in the mantle transition zone (MTZ) with a value of 0.1–1 wt% (with large regional variations). When water-rich MTZ materials are transported out of the MTZ, partial melting occurs. Vertical direction of melt migration is determined by the density contrast between the melts and coexisting minerals. Because a density change associated with a phase transformation occurs sharply for a solid but more gradually for a melt, melts formed above the phase transformation depth are generally heavier than solids, whereas melts formed below the transformation depth are lighter than solids. Consequently, hydrous melts formed either above or below the MTZ return to the MTZ, maintaining its high water content. However, the MTZ water content cannot increase without limit. The melt-solid density contrast above the 410 km depends on the temperature. In cooler regions, melting will occur only in the presence of very water-rich materials. Melts produced in these regions have high water content and hence can be buoyant above the 410 km, removing water from the MTZ. Consequently, cooler regions of melting act as a water valve to maintain the water content of the MTZ near its threshold level (~ 0.1–1.0 wt%). Mass-balance considerations explain the observed near-constant sea-level despite large fluctuations over Earth history. Observations suggesting deep-mantle melting are reviewed including the presence of low-velocity anomalies just above and below the MTZ and geochemical evidence for hydrous melts formed in the MTZ. However, the interpretation of long-term sea-level change and the role of deep mantle melting in the global water circulation are non-unique and alternative models are reviewed. Possible future directions of studies on the global water circulation are proposed including geodynamic modeling, mineral physics and observational studies, and studies integrating results from different disciplines.

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