scholarly journals "Quantitative and Qualitative Study of Diatoms Around Fifh Cage in the Southern Basin of the Caspian Sea"

2021 ◽  
Vol 35 (2) ◽  
Author(s):  
Fatemeh Sadat Tahami
Keyword(s):  
Qualitative Study ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Southern Basin

Genetic variability and population structure of Capoeta gracilis (Keyserling 1861) populations in the southern basin rivers of the Caspian Sea as revealed by the mtDNA sequences

2020 ◽  
Vol 67 (2) ◽  
Author(s):  
Hassan Malvandi ◽  
Abbas Esmaili Sari ◽  
Mansour Aliabadian
Keyword(s):  
Caspian Sea ◽  
Genetic Difference ◽  
Haplotype Diversity ◽  
Population Expansion ◽  
The Caspian Sea ◽  
Northern Iran ◽  
Southern Basin ◽  
Selective Neutrality ◽  
Gene Sequence Analysis ◽  
Genetic Structure And Diversity

This study investigated the genetic structure and diversity of Capoeta gracilis (Keyserling 1861) from the southern basin of the Caspian Sea employing cytochrome b gene sequence analysis. For this purpose, a total of 83 specimens of this species were sampled and analysed from four rivers viz., CheshmeKile, Siahrood, Tajan and ZarrinGol. Nucleotide diversity ranged from 0.00030 to 0.00715 and haplotype diversity from 0.27895 to 0.68421 for the populations studied. A total of 14 haplotypes were obtained and haplotype no. 2 was shared by all. Pairwise FST analysis showed that there was a significant genetic difference between the populations studied, with the exception of the populations living in the Siahrood and Tajan rivers. Analysis of molecular variance (AMOVA) also confirmed the genetic differentiation among populations showing 76.03% of the genetic variation within populations and 23.97% among populations (p<0.01). A selective neutrality test showed that populations of C. gracilis were probably in equilibrium and were not experiencing a population expansion. In general, it can be said that distinct populations of this species are living in the rivers of northern Iran, though further studies using other genes and molecular markers are needed to confirm the findings.

Examining Relationships Between Socioeconomic Factors and Landscape Metrics in the Southern Basin of the Caspian Sea

2016 ◽  
Vol 21 (5) ◽  
pp. 669-680 ◽  
Author(s):  
Bahareh Ghafouri ◽  
Bahman Jabbarian Amiri ◽  
Afshin Alizadeh Shabani ◽  
Melissa Songer
Keyword(s):  
Socioeconomic Factors ◽  
Landscape Metrics ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Southern Basin

scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

2018 ◽  
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbasali Aliakbari Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Potential Vorticity ◽  
Caspian Sea ◽  
Gravity Current ◽  
Bottom Friction ◽  
Density Difference ◽  
Dynamical Model ◽  
Western Coast ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Simple Dynamical Model

Abstract. This study investigates the deep gravity current between the middle and southern Caspian Sea basins, caused by density difference of deep waters. Oceanographic data, numerical model and dynamic models are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional ocean model COHERENS results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference mainly due to the temperature difference between the middle and southern basins especially in winter. For this reason, water sinks in high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use an analytic model for the overflow gravity current with inertial effects, bottom friction and entrainment, to consider its structure. The dynamical characteristics of this deep baroclinic flow are investigated with different initial and boundary conditions. The results show that after time passes, the flow adjusts itself, moving as a deepening gravity driven topographically trapped current. This flow is considered for different seasons and its velocity and width are obtained. Because of the topography of the Southern Caspian basin, the flow is trapped after the sill; thus, another simple dynamical model of the overflow, based on potential vorticity similar to that of Bidokhti and Ezam (2009) but with the bottom friction and entrainment included, is used to find the horizontal extent of the outflow from the western coast. To estimate the changes of vorticity and potential vorticity of the flow over the Absheron sill, we use the method of Falcini and Salusti (2015), in this work, the effects of entrainment and friction are considered. Because of the importance of the overflow in deep water ventilation, a simple dynamical model of the boundary currents based on the shape of strait is used to estimate typical mass transport and flushing time which is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This time scale is important for the possible effects on the ecosystem here of pollution due to oil exploration.

scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 459-476
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbasali Aliakbari Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Caspian Sea ◽  
Oil Pollution ◽  
Gravity Current ◽  
Ocean Model ◽  
Density Difference ◽  
Cold Weather ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Flushing Time ◽  
Southern Caspian Sea

Abstract. The present study investigates the deep gravity current between the middle and southern Caspian Sea basins caused by the density difference of deep waters. Oceanographic data, a numerical model and a dynamic model are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional COHERENS ocean model results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference, which is mainly owing to the temperature difference, between the middle and southern basins, especially in winter. Due to cold weather in the northern basin, water sinks at high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use the analytic model of Falcini and Salusti (2015) for the overflow gravity current to estimate the changes in the vorticity and potential vorticity of the flow over the Absheron sill; the effects of entrainment and friction are also considered. Due to the importance of the overflow with respect to deep water ventilation, a simple dynamical model of the boundary currents based on the shape of the Absheron Strait is used to estimate typical mass transport and flushing time; the flushing time is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This timescale is important for the region's ecosystem and with respect to the impacts of pollution due to oil exploration. In addition, by reviewing the drilled oil and gas wells in the Caspian Sea, the results show that the deep overflow moves over some of these wells. Thus, the deep flow could be an important factor influencing oil pollution in the deeper region of the southern Caspian Sea.

scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

2017 ◽  
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbas Ali AliAkbbari-Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Caspian Sea ◽  
Dynamic Models ◽  
Gravity Current ◽  
Ocean Model ◽  
Density Difference ◽  
Dynamical Model ◽  
Western Coast ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Simple Dynamical Model

Abstract. This study investigates the deep gravity current between the middle and southern Caspian Sea basins, caused by density difference of deep waters. Oceanographic data, numerical model and dynamic models are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional ocean model COHERENS results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference mainly due to the temperature difference between the middle and southern basins especially in winter. For this reason, water sinks in high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use an analytic model for the overflow gravity current with inertial and frictional effects to consider its structure. The dynamical characteristics of this deep baroclinic flow are investigated with different initial and boundary conditions. The results show that after time passes, the flow adjusts itself, moving as a deepening gravity driven topographically trapped current. This flow is considered for different seasons and its velocity and width are obtained. Because of the topography of the Southern Caspian basin, the flow is trapped after the sill; thus, another simple dynamical model of the overflow, based on potential vorticity conservation similar to that of Bidokhti and Ezam (2009) but with the bottom friction included, is used to find the horizontal extent of the outflow from the western coast. The result of this model shows that the Rossby length (deformation radius) of the flow decreases when drag coefficient increases. Because of the importance of the overflow in deep water ventilation, a simple dynamical model of the boundary currents based on the shape of strait is used to estimate typical mass transport and flushing time which is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This time scale is important for the possible effects of pollutions due to oil exploration on the ecosystem of this water body.

scholarly journals Genome Reconstruction from Metagenomic Data Sets Reveals Novel Microbes in the Brackish Waters of the Caspian Sea

2016 ◽  
Vol 82 (5) ◽  
pp. 1599-1612 ◽  
Author(s):  
Maliheh Mehrshad ◽  
Mohammad Ali Amoozegar ◽  
Rohit Ghai ◽  
Seyed Abolhassan Shahzadeh Fazeli ◽  
Francisco Rodriguez-Valera
Keyword(s):  
Caspian Sea ◽  
Metagenomic Data ◽  
Data Sets ◽  
The Caspian Sea ◽  
Environmental Distribution ◽  
Content Type ◽  
Southern Basin ◽  
Brackish Waters ◽  
Phylogenetic Placement ◽  
Degree Of Overlap

ABSTRACTWe present here the findings from a study of the microbiome of the southern basin of the Caspian Sea, the largest water body on Earth disconnected from any ocean and a brackish inland sea. By high-throughput metagenomics, we were able to reconstruct the genomes of representative microbes. The gross community structure (at the phylum level) was different from the structure of typical marine and freshwater communities in temperate open oceans, with the Caspian Sea having freshwater-like amounts ofActinobacteriaandAlphaproteobacteria, whileGammaproteobacteriaandBetaproteobacteriawere present at intermediate levels. We assembled the genomes of several groups and provide detailed descriptions of partial genomes fromActinobacteria,Thaumarchaea, andAlphaproteobacteria. Most belonged to hitherto unknown groups, although they were related to either marine or freshwater groups. The phylogenetic placement of the Caspian genomes indicates that the organisms have multiple and separate phylogenetic origins and that they are related to organisms with both freshwater and marine lineages. Comparative recruitment from global aquatic metagenomes indicated that most Caspian microbes are endemic. However, some Caspian genomes were recruited significantly from either marine water (a member of theAlphaproteobacteria) or freshwater (a member of theActinobacteria). Reciprocally, some genomes of other origins, such as the marine thaumarchaeon “CandidatusNitrosopelagicus” or the actinobacterium “CandidatusActinomarina,” were recruited from the Caspian Sea, indicating some degree of overlap with the microbiota of other water bodies. Some of these microbes seem to have a remarkably widespread geographic and environmental distribution.

THE NUMBER AND QUALITATIVE CHARACTERISTICS OF FRY FISH IN SHALLOW COASTAL WATERS OF THE VOLGA IN THE SUMMER-AUTUMN PERIOD OF 2012

2017 ◽  
pp. 65-73
Author(s):  
Edward Vladimirovich Nikitin
Keyword(s):  
Fish Species ◽  
Coastal Waters ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Volga River ◽  
Commercial Fish ◽  
Autumn Period ◽  
Fish Juveniles ◽  
Qualitative Characteristics ◽  
Shallow Coastal Waters

Shallow coastal waters of the Volga river is a flooded feeding area for fish juveniles of nonmigratory fish species. There takes place annual downstream migration of fluvial anadromous fish species from spawning grounds of the Volga river to the Northern Caspian Sea. The most important factors determining the number and qualitative characteristics of fry fishes are the level of the Caspian Sea (currently having a tendency to the lowering), hydrological and thermal regimes of the Volga river. Researches were carried out in definite periods of time. In the summer-autumn period of 2012 fry fishes were presented by 19 species (13 of them were commercial species), which belonged to 9 families. The article gives data on all the commercial fish species. In the first decade of July the maximum number of fry fish was registered in the western part of the Volga outfall offshore - in box 247 (19.86 mln specimens/km2), in the eastern part - in box 142 (20.4 mln specimens/km2). The most populous were roach, red-eye, silver bream and bream; size-weight characteristics were better in the areas remoted from the Volga delta. In the third decade of July the quantitative indicators of fry fish on these areas decreased, size-weight characteristics greatly increased. In the second decade of October in the western part of the seaside there were registered increased pre-wintering concentrations of fish juveniles, their qualitative indicators increased, which is evidence to favorable feeding conditions in 2012.

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