scholarly journals RETROSPECTIVE ANALYSIS OF RESTRUCTURING IN COMPOSITION OF MACROZOOBENTHOS UNDER CASPIAN SEA TRANSGRESSION

2021 ◽  
Vol 2021 (2) ◽  
pp. 47-54
Author(s):  
Anna Viktorovna Mikhajlova
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Oxygen Deficiency ◽  
Aquatic Organisms ◽  
High Water ◽  
Bottom Fauna ◽  
Species Structure ◽  
The Caspian Sea ◽  
Retrospective Nature ◽  
Quantitative Changes

The article highlights the processes of lowering and raising the Caspian Sea level and its influence on the quantitative and qualitative characteristics of the aquatic bioresources, including zoobenthos. The development of macrozoobenthos in the Caspian Sea including the Northern Caspian is associated with various processes: chemical, physical and biological. The presence of macrozoobenthos determines the fish productivity in the sea, it is an integral part of the ecosystem of the northern part of the Caspian Sea. In this regard, the assessment of the composition and quantitative characteristics of bottom communities becomes important. One of the urgent tasks of modern hydrobiology is detecting the basic regularities in the biotic processes that affect the qualitative and quantitative changes in the aquatic organisms. This research is of a retrospective nature. On the basis of a long-term analysis of the dynamics of the species structure of bottom zoocenoses there have been revealed the changes in the macrozoobenthos of the western part of the Northern Caspian in the first and second periods of the sea level rise (1978–1988 and 1989–1995). Decreasing water salinity, increasing desalinated zones and areas with oxygen deficiency in the bottom horizon (in the extremely high-water years of 1990 and 1991) contributed to the significant changes in the quantitative and qualitative composition of the bottom fauna. From the first stage to the second there was recorded a decrease in the number and biomass of crustaceans and molluscs. The species Stenogammarus macrurus (G. O. Sars) and Stenogammarus similis (G. O. Sars), which are tolerant to the significant salinity fluctuations, as well as abra, which is resistant to oxygen deficiency were most abundant in the water complex with light salinity. Also, there has been considered the water content of the rivers of the Caspian basin and the type of soil as factors influencing changes in the concentration of macrozoobenthos.

RETROSPECTIVE ANALYSIS OF CATCHES AND STOCK DYNAMICS OF RUDD IN VOLGA-CASPIAN AND NORTHERN CASPIAN SUBAREAS

Fisheries ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 52-56
Author(s):  
Tatiana Vetlugina
Keyword(s):  
Retrospective Analysis ◽  
Sea Level ◽  
Caspian Sea ◽  
High Water ◽  
Abundant Species ◽  
The Caspian Sea ◽  
Large Group ◽  
Runoff Volume ◽  
Term Analysis

Rudd is one of the most abundant species in the large group of minnow in the Volga-Caspian and Northern-Caspian fishery subareas of the Volga–Caspian fishery basin south. The article contains the data on its catches and usable stocks during ХХ – ХХI centuries. A long term analysis of the rudd catches and the runoff volume during the spring high water showed no substantial connection between these processes due to the rudd’s ecological peculiarities. The dynamics of the rudd catches and the level of the Caspian Sea are connected in inverse ratio. Inverse correlations with high determination coefficients between the rudd catches, the usable stocks, and the sea level were obtained.

scholarly journals Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

Ocean Science ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 311-329 ◽  
Author(s):  
R. A. Ibrayev ◽  
E. Özsoy ◽  
C. Schrum ◽  
H. İ. Sur
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Caspian Sea ◽  
Seasonal Cycle ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Coastal Currents ◽  
The Caspian Sea ◽  
Sea Surface Topography

Abstract. A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. The model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

scholarly journals Cadmium content in aquatic organisms of the Caspian Sea

2022 ◽  
Vol 16 (4) ◽  
pp. 37-46
Author(s):  
T. S. Ershova ◽  
V. F. Zaitsev ◽  
V. A. Chaplygin ◽  
A. S. Khursanov
Keyword(s):  
Caspian Sea ◽  
Aquatic Organisms ◽  
Cadmium Content ◽  
The Caspian Sea

scholarly journals Features of seasonal changes of the Caspian Sea level

2019 ◽  
Author(s):  
E.S. Safarov ◽  
◽  
J.-F. Cretaux ◽  
R.M. Mammadov ◽  
A. Arsen ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Seasonal Changes ◽  
The Caspian Sea

Tsunami Hazard of the Caspian Sea

2021 ◽  
Author(s):  
Alisa Medvedeva ◽  
Igor Medvedev
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Tsunami Hazard ◽  
Seismic Sources ◽  
Deterministic Approach ◽  
The Caspian Sea ◽  
Tsunami Waves ◽  
The Mean ◽  
Run Up ◽  
Sea Coast

<p>A regional model of tsunami seismic sources in the zone of the Main Caucasian thrust has been developed. The parameters of probable models of seismic sources and their uncertainties were estimated based on the available data on historical earthquakes and active faults of the region. The scenario modeling technique was used for the tsunami zoning of the Caspian Sea coast. The time period covered by the model catalog of earthquakes used to calculate the generation and propagation of tsunamis is about 20 000 years, which is longer than the recurrence periods of the strongest possible earthquakes. The recurrence graphs of the calculated maximum tsunami heights for the entire sea coast were plotted. On their basis, the maximum heights of tsunami waves on the coast were calculated with recurrence periods of 250, 500, 1000 and 5000 years and the corresponding survey maps of the tsunami zoning of the Caspian Sea were created. The algorithm for calculating the tsunami run-up on the coast is improved, taking into account the residual (postseismic) displacements of the bottom and land relief. Estimates of tsunami hazard for the coast near the city of Kaspiysk were carried out: within the framework of the deterministic approach, the maximum wave heights and run-up distance were calculated. It is shown that the deterministic approach slightly overestimates the maximum heights of tsunami waves with certain return periods. It is shown that changes in the mean sea level can affect the features of the propagation of tsunami waves in the Caspian Sea. Thus, at an average sea level of -25-26 m, the Kara-Bogaz-Gol Bay is linked with the entire sea through a narrow strait. It leads to the propagation of tsunami waves into the water area of the bay and a decrease in wave height on the eastern coast of the sea. When the mean sea level decreases below -27 m, the positive depths in the strait disappear and water exchange through the strait stops, and the wave height in this part of the sea increases.</p>

Caspian Sea-level changes at the end of Little Ice Age and its impacts on the avulsion of the Gorgan River : a multidisciplinary case study from the southeastern flank of the Caspian Sea

2014 ◽  
pp. 145-155 ◽  
Author(s):  
Abdolmajid Naderi Beni ◽  
Hamid Lahijani ◽  
Morsen Pourkerman ◽  
Rahman Jokar ◽  
Muna Hosseindoust ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Little Ice Age ◽  
Ice Age ◽  
Sea Level Changes ◽  
The Caspian Sea
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