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Oil spills pose significant threats to marine and coastal ecosystems, necessitating advanced methodologies for environmental sensitivity and vulnerability assessments. This study enhances existing frameworks to better manage oil spill risks in the Caspian Sea, a region characterized by its ecological sensitivity and economic dependence on oil extraction. Utilizing the Environmental Sensitivity Index (ESI), we adapted global standards to the unique conditions of the Caspian Sea and built a sensitivity map of the coastline, which later became one of the components of the integral sensitivity map for the entire Caspian Sea, which includes several biotic and abiotic components. We also developed a comprehensive geodatabase incorporating topographic, infrastructural, and hydrodynamic data. Through the sophisticated modeling of oil spill scenarios using the Oil Spill model of the MIKE 21 software (Release 2016) suite, we simulated spills of varying magnitudes to analyze their potential impacts on the marine and coastal environment. The results enabled the creation of vulnerability maps, pinpointing areas at highest risk and facilitating strategic response planning. Our study demonstrates the critical importance of integrating advanced geospatial analyses and dynamic modeling techniques to improve oil spill preparedness and response strategies. The findings of this study suggest that enhanced monitoring and adaptive management strategies are essential for protecting the Caspian Sea from environmental risks posed by its oil industry. [ABSTRACT FROM AUTHOR]

The Caspian Sea, the world's largest inland body of water, supports a highly diverse community of phytoplankton species that play a crucial role in its ecosystem and overall food web dynamics. This unique, enclosed environment, which spans several countries, is subject to various ecological pressures, including climate change and anthropogenic activities, making it a critical area for biodiversity research. In this study, a comprehensive checklist of these species has been compiled based on an extensive literature review, revealing a total of 970 species and subspecies from 242 genera across 7 phyla. Bacillariophyceae was identified as the dominant class, comprising 347 species (36.37%), followed by Chlorophyta with 289 species (30.29%) and Cyanobacteria with 190 species (19.92%). Other notable groups include Myzozoa with 72 species (7.55%), Ochrophyta with 56 species (5.87%), Cryptophyta with 13 species (1.36%), and Haptophyta with 3 species (0.31%). This detailed inventory provides essential data on the phytoplankton biodiversity in the Caspian Sea, contributing to a deeper understanding of its ecological complexity. The checklist not only highlights the diversity within each phylum but also emphasizes the dominance of diatoms and chlorophytes, which are key to the sea's primary productivity. These findings serve as a critical resource for future ecological and environmental assessments, offering a baseline for monitoring biodiversity changes, potential threats to the ecosystem, and the impacts of climate change and human activities. The rich phytoplankton diversity outlined in this study shows the ecological significance of the Caspian Sea and its importance for regional and global biodiversity conservation efforts. [ABSTRACT FROM AUTHOR]

The paper contains information about the current state of habitats of species of the orders Charadriiformes, Ciconiiformes, and Gruiformes found in the southern coastal part of the Caspian Sea, the influence of anthropogenic factors on their habitability, and the status of species included in international conventions. It was revealed that, 24 species found in the southern coastal part of the Caspian Sea have the status of global protection. Of the 154 species with European conservation status, only 48 are eligible for higher global conservation statuses. That is, 3 species are in crisis, 13 species are endangered and 29 species are vulnerable. The number of 2 species is unknown, and there is no sufficient information about 1 species. [ABSTRACT FROM AUTHOR]

The choice of temporal resolution has high importance in ecological modeling, which can greatly affect the identification of the main drivers of an organism's distribution, considering the spatiotemporal dynamism of environmental predictors as well as organisms' abundance. The present study aimed to identify the spatiotemporal distribution patterns of Caspian Kutum, Rutilus frisii, along the southern coast of the Caspian Sea, north of Iran, evaluating multiple temporal resolutions of data. The boosted regression trees (BRT) method was used to model fish catch distribution using a set of environmental predictors. Three temporal scales of data, including seasonal, sub‐seasonal, and monthly time frames over the catch season (October–April), were considered in our modeling analyses. The monthly models, utilizing more detailed data scales, exhibited the highest potential in identifying the overall distribution patterns of the fish, compared to temporally‐coarse BRT models. The best models were the BRTs fitted using data from March and April, which represented the final months of the catch season with the highest catch levels. In the monthly models, the main determinants of the Kutum's aggregation points were found to be dynamic variables including sea surface temperature, particulate organic and inorganic carbon, as opposed to static topographic parameters such as distance to river inlets. Seasonal and sub‐seasonal models identified particulate inorganic matter and distance to river inlets as the predictors with the highest influence on fish distribution. The geographical distributions of fish biomass hotspots revealed the presence of a stable number of fish aggregation hotspot points along the eastern coast, while some cold‐spot points were identified along the central and western coasts of the Caspian Sea. Our findings indicate that utilizing fine time scales in modeling analyses can result in a more reliable explanation and prediction of fish distribution dynamics. The investigated approach allows for the identification of intra‐seasonal fluctuations in environmental conditions, particularly dynamic parameters, and their relationship with fish aggregation. [ABSTRACT FROM AUTHOR]

This study examines the changes in current speeds and the related energies in the Caspian Sea using the Princeton Ocean Model (POM) output during 2018. Identifying and extracting eddies is crucial for determining the energy transfer of water masses, as well as the distribution of temperature and salinity. The results indicate that temperature variations at the western boundary of the central basin during cold months reflect the inflow of cold waters from the northern basin to the western section due to the counterclockwise circulation of the central basin. Moreover, in warm seasons, the decrease in temperature at the eastern boundary compared to the western boundary may be attributed to the phenomenon of upwelling. Furthermore, the changes in eddy kinetic energy (EKE) relative to mean kinetic energy (MKE) are associated to variations in Reynolds stress (RS). During warm seasons, the positive trend in RS, which signifies a change in flow direction, leads to an increase in the difference between EKE and MKE. [ABSTRACT FROM AUTHOR]

Copyright of Bylye Gody is the property of Cherkas Global University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large-sized specimens of a new for the Caspian Sea mollusk were found in spring 2023 in trawl catches of the survey conducted by the Volga-Caspian branch (CaspNIRKH) of the Russian Res. Inst. of Fisheries and Oceanography. Using molecular genetics research methods, including sequencing of the cytochrome oxidase gene of mitochondrial DNA, the species is identified as Mytilus galloprovincialis — the Black Sea mussel. In summer, the invaders were recorded in bottom samples in several areas of the sea. Features of the species biology allow its naturalization into the Caspian Sea ecosystem that will contribute to enrichment of the food base for fish and involve this filter-feeding mollusk to the processes of self-purification of the sea.

Introduction: Treatment of municipal wastewater is essential to remove bacteria. This study is designed to evaluate the efficacy of a wastewater treatment plant (WWTP) for the removal of bacteria and using for irrigation or discharge in the Caspian Sea according to the World Health Organization (WHO) regulations. Materials and Methods: A total of 105 samples were collected from 7 stations, including the inlet and the outlet of the WWTP in Bandargaz City (Iran), the intersection point of wastewater effluent with Caspian Sea (Gorgan Bay), and a radius of 200 meters in three directions east, west, and north of the intersection point of wastewater in Gorgan Bay. The multiple-tube fermentation technique was used to enumerate bacteria, and results were expressed as the Most Probable Number (MPN) per 100 ml. Results: Bacteriological analysis exhibited that the concentration of total coliform, fecal coliform, fecal streptococci, and Clostridium perfringens were 1.38 ×1010, 5.57 × 107, 5.53 × 109, 1.26 × 109 in inlet, and 1.38 × 1010 , 5.57 × 107, 5.53 × 109 , 1.26 × 109 in outlet of WWTP, respectively. Conclusion: The aeration lagoon has a low performance in bacteria population removal, which may be due to the climate condition of this region (few sunny days and many cloudy and rainy days). This effluent was not generally acceptable for discharge in the environment and reuse. Therefore, it is essential to modify the disinfection process to keep the concentration of bacteria under control. Additionally, continuous monitoring is necessary to control the quality of wastewater before discharge into the environment or reuse.

Introduction. The use of environmentally-friendly engineering systems including solar energy technologies makes it possible to reduce energy costs and therefore to lower production costs and anthropogenic stress on the environment. Aim of the Study. The authors used innovative techniques to assess the thermal resource potential of solar radiation, to analyze the salt deposits of the Kara-Bogaz-Gol Gulf as thermal accumulators for the development, introduction and use of solar thermal technologies and to justify the technical and economic feasibility of their use in engineering systems in the Kara-Bogaz-Gol Gulf (Caspian region). Meterials and Methods. The study design is based on systematic theoretical calculations of the gross, technical, economic and ecological potentials of solar radiation taking into account environmental conditions. For calculating there were used the methods of mathematical modeling of heat and mass transfer processes in active solar energy systems when converting solar energy into thermal energy in the salty reservoir of the Kara-Bogaz-Gol Gulf as a “solar pond”. Results. There have been assessed the solar energy characteristics for the introduction of various engineering storage systems and technologies. There have been determined the results of energy storage on the reservoir salt surface during the day: in winter – 1 009.0 W/m2 per day, in summer – 1 574.7 W/m2 per day. It has been proven that the potential of solar energy conversion into thermal energy varies from 40 to 70% depending on the season. Aaccording to theoretical calculations, the solar pond efficiency in winter is 11.4% and in summer – 14.6%. In summer, there was measured the average temperature on the salt surface of the reservoir bottom, it ranges from 55.04 to 79.8 ºC, in winter from 20.0 to 25.6 ºC. Discussion and Conclusion. The results obtained can be used for strengthening energy security, developing energy systems and producing autonomous thermal power devices based on solar energy that will reduce the energy consumption of fossil fuels and improve the environmental situation in the region. The materials of the article can be used in preparing design estimates and feasibility study for developing various solar energy systems and technologies in the Caspian region.

Heavy metal pollution of the bottom sediments in the Northern Caspian Sea region was assessed for the period from 2012 to 2021. The concentrations and pollution levels of heavy metals were determined using the standard indices as part of the industrial environmental monitoring at the license site in the northern part of the Caspian Sea. Based on the concentrations of all identified metals (zinc, copper, lead, cadmium, nickel, iron, and manganese), significant spatial and temporal variations were observed. The values obtained did not exceed those of international sediment quality standards, thus suggesting that the studied bottom sediments were only slightly polluted by heavy metals. However, certain areas showed high levels of pollution, such as the northwestern area with the elevated iron levels and the central area with the maximum lead and cadmium concentrations. The statistical analysis of geochemical parameters of the bottom sediments revealed distinct patterns in the distribution of heavy metals.

The Caspian pond turtle, Mauremys caspica, is an important reptile species in the southern basin of Caspian Sea. Haematological indices and serum biochemistry can be utilised as valuable screening tools for the health status of many domestic and wild animals. In this study, the blood parameters were measured in male and female turtles to establish physiologic reference ranges of selected haema-tological and serum biochemical parameters in M. caspica. For this purpose, blood samples were collected from 60 Caspian pond turtles (30 males and 30 females) from the southern basin of Caspian Sea. Significant differences were observed in some haematological indices (i.e. haemoglobin and haematocrit) and serum biochemical indices (i.e. alkaline phosphatase, aspartate aminotransferase, and creatine kinase) between the male and female turtles (P

Cheshmeh Kileh and Shiroud in southern Caspian Sea have very important as habitats for the migration and reproduction of valuable fishery species. According to the agricultural industry in the north of Iran, products such as kiwi fruits, citrus fruits, rice and greenhouse products are the dominant products in this area. EC and pH are one of the important parameters in agricultural sciences. Therefore, conducting comprehensive studies to determine factors affecting the chemical composition of water and sediment along the rivers can help to identify pollutants and controlling factors of water chemistry and the sustainable development of the region. Sampling sites were determined based on the geogenic and anthropogenic effects, and samples were collected in September 2021. Hydrogeochemical diagrams, irrigation, industrial and HMs indices were drawn or calculated. The results showed that one sample in Sehazar sub-river is under the influence of gypsum lithology in the Karaj Formation located upstream of Maran heights. In Cheshmeh Kileh Catchment, one sample had a higher amount of bicarbonate, sodium, potassium and HMs ions than other samples due to the infiltration of landfill waste water. Diagrams for Shiroud Catchment showed that in the estuary, the phenomenon of saltwater intrusion has occurred due to excessive sand and gravel harvesting. Therefore, the corrosion rate in this station is high, and for the construction of metal and reinforced concrete structures, caution and further investigations should be used to prevent damages. It is also suggested that EC and pH values are always controlled in agricultural activities.Article Highlights: The Cheshmeh Kileh and Shiroud are the most important rivers in western Mazandaran Province and ending at the Caspian Sea. Both rivers are very important as habitats for the migration and reproduction of valuable fishery species. In this area, the agricultural industry is very popular and they generally use surface water for irrigation. Based on the studies conducted on water samples, the dominant type in both catchments is calcium bicarbonate. The Cheshmeh Kileh catchment is affected by gypsum lithology in Karaj Formation (upstream) and landfill leachate in some samples. The Shiroud Catchment is affected by basalt lithology and saltwater intrusion in the river (estuary). [ABSTRACT FROM AUTHOR]

The Caspian pond turtle, Mauremys caspica, is an important reptile species in the southern basin of Caspian Sea. Haematological indices and serum biochemistry can be utilised as valuable screening tools for the health status of many domestic and wild animals. In this study, the blood parameters were measured in male and female turtles to establish physiologic reference ranges of selected haematological and serum biochemical parameters in M. caspica. For this purpose, blood samples were collected from 60 Caspian pond turtles (30 males and 30 females) from the southern basin of Caspian Sea. Significant differences were observed in some haematological indices (i.e. haemoglobin and haematocrit) and serum biochemical indices (i.e. alkaline phosphatase, aspartate aminotransferase, and creatine kinase) between the male and female turtles (P<0.05). However, further research is necessary to elucidate the influence of size, sex, season, and habitat variations on haemato-biochemical parameters in the Caspian pond turtle. [ABSTRACT FROM AUTHOR]

The ice regime of the Caspian Sea has pronounced influence on the heat and moisture exchange of the reservoir with the atmosphere, the state of the ecosystem, as well as human marine activities, including shipping, fishing, construction of hydraulic structures, etc. Consequently, the development of existing ideas about the causes of changes in the characteristics of the ice regime of such water bodies is actual and socially significant problem of limnology, hydrometeorology, ecology, and navigation. This study was aimed at determination the frequency of occurrence of atmospheric blockings over the Caspian region with standings longer 5 days in winter period of 1959–2022, and investigation of influence of them on the ice regime in the Northern area of the Sea. The following information and data were used: changes in hourly mean values of atmospheric pressure at the sea level, geopotential of isobaric surfaces 850, 500 and 300 hPa, presented in the ERA5 reanalysis; and observational data on air temperature and ice cover from hydrometeorological stations located in the Caspian region of Kazakhstan and Russia. It has been established that in the winter during a long standing of atmospheric blockings the mean daily air temperatures noticeably drop. The values of all the studied characteristics of every atmospheric blocking which occurred in 1959–2022 were estimated as well the influence of them on the ice regime in the North of the Caspian Sea was analyzed. The relationship between a decrease in the frequency of atmospheric blockings (AB), sums of negative air temperatures on its coasts, and the ice cover thickness in the corresponding areas of coastal waters has been revealed in the region. The longer the total AB duration, the lower is the air temperature, and the ice thickness in February is larger.

Objective: To explain the indicators and components affecting the military dimension of the maritime security of the IRIran in the Caspian Sea and its sub-goals, to explain the challenges of the maritime security of the IRIran in the Caspian Sea and to identify the most important military factors affecting the maritime security IRIran in the Caspian Sea and determining the relationships between indicators and components affecting the military dimension of maritime security IRIran is in the Caspian Sea.Methodology:The type of applied research and its approach is mixed and descriptive-analytical and content analysis. The statistical population of this research is 90 people. Qualitative data analysis with the method (data classification, processing and judgment) and quantitative data with descriptive analysis method and inferential analysis of the collected data using the test Chi2 and using software SPSS has been evaluated.Findings:One of the important findings is that the significant presence of the AJA Navy in the Caspian Sea, as well as the special attention of the relevant authorities to international relations and the development of maritime defense diplomacy in order to strengthen the maritime security of the IRIran in the Caspian Sea. Results: By calculating the inferential values in the three military and security dimensions, the economic dimension and the political and legal dimension and comparing with the critical values, all indicators and components related to the three dimensions have been confirmed. According to the calculated agreement coefficient, the relationship of all indicators with components and dimensions was confirmed.

The study highlights the specifics of the everyday work of the merchants of the Astrakhan and Orenburg Governorates in the fishing industry. Emphasis is placed on the activities of entrepreneurs who explored the waters of the Asian region in the 19th century – the Caspian and Aral Seas, as well as the Emba, Amu Darya and Syr Darya rivers. The purpose of the study is to analyze the specifics of fishing in the 19th century as one of the spheres of merchant entrepreneurship in the Asian direction. The choice of geographical boundaries is dictated by the desire to study the merchant fishing industry of the frontier regions of Russia as a branch of merchant business focused on the economic development of Asian territories. The paper presents the fundamental differences in working conditions between Astrakhan and Orenburg entrepreneurs. The article shows a wide range of organizational tasks solved by merchants in preparation for fishing operations. The localization of labor activity in the places of residence of Asian nomads (Kazakhs, Kalmyks, Turkmens) attributed unique character to the fishing business of the Astrakhan and Orenburg merchants of the 19th century. Merchants doing business in the depths of barely explored territories with little or no presence of Russian military were regularly attacked by steppe nomads. Conflicts of this kind led to the theft or destruction of the property of fishermen and sometimes ended in the death of merchants and their employees. To date, Russian historiography has not offered an analysis of the merchant fishing industry in the Asian direction in the 19th century in the aspect of everyday work, which brings novelty to the presented study.

The Sefidrud River, which flows into the Caspian Sea after traversing the northern Iranian province of Guilan, is the principal river in the southern Caspian Sea. Its water is utilized for drinking, agriculture, and aquaculture, while industrial and agricultural wastewater is discharged into this valuable body of water. This study aimed to measure the concentration of two heavy metals, nickel and lead, and organochlorine toxins in the water and sediment of this river. Water samples were taken from the Sefidrud River at three stations in four seasons to measure the concentration of the above-mentioned two heavy metals organochlorine toxins as well as some physiochemical parameters of the water. Results showed that the annual mean water temperature, calcium, magnesium, electrical conductivity (EC), T.D.S, pH, and dissolved oxygen in water samples were 16.35°C, 77 mg/l, 28.41 mg/l, 1245.41 mS/m, 782.7, 8.01, and 7.91 mg/l. The mean annual concentration of nickel and lead was also 0.008 ± 0.001 and 0.001 ± 0 mg/l in water and 29.75 ± 1.19 and 313.4 ± 17.13 mg/l in sediments. The results also showed that the mean annual concentration of Pertilachlor was 0.40 ± 0.046 mg/l in water and 2.91 ± 0.476 mg/l in sediments, and the mean annual concentration of Saturn was 2.81 ± 0.47 mg/l in water and 0.39 ± 0.47 mg/l in sediments. Since the sediments of the Sefidrud River contain relatively high concentrations of heavy metals such as lead and nickel as well as organochlorine toxins, the river should be regarded as polluted; therefore, the discharge of pollutants and wastewater into this river should be properly managed. [ABSTRACT FROM AUTHOR]

Sampling was done over a year (December 2020–November 2021) to study the distribution and species composition of phytoplankton in the southwestern Caspian Sea. Sea water from various depths was collected along four transects: Lisar, Anzali, Sefidrood and Chaboksar, with a total of 12 stations. A comparison was then made with the data collected in 1996 to look at the long-term changes. The increase in sea water temperature and salinity, especially in summer, was observed in the present study, which was possibly due to global warming and climate change. Amongst 48 identified phytoplankton species, Bacillariophyta (80.0%) and Cyanophyta (11.0%) were dominant. Phytoplankton abundance was measured as 99,775 ± 30,200 cell L−1 on average. The highest abundance was a non-native species Pseudo-nitzschia seriata (H. Peragallo 1900) from Bacillariophyta with more than 17,000 cell L−1, followed by another toxic species Nodularia spumigena (Mertens ex Bornet and Flahault 1888) from Cyanophyta. The N. spumigena species had the highest abundance as 5,000,000 cell L−1 in July 2021 at the Anzali region. Nutrient increase of more than threefold in 2020–2021 has caused a sevenfold increase of chlorophyll-a as compared to that in 1996. The increases in nutrients levels, sea surface temperature (> 30 °C) and salinity are generally regarded as important factors to cause variations in phytoplankton abundance and composition. The sevenfold increase of phytoplankton abundance between 1996 and 2020–2021 and change of trophic state from oligotroph to mesotroph, indicated the increase of stress and pressure on the native phytoplankton community. [ABSTRACT FROM AUTHOR]

This research paper analyzes satellite altimetry data for the northeastern and middle parts of the Caspian Sea for the period from 1993 to 2023. The verification of altimeter data from the data of marine hydrometeorological stations of nasal observations of the permanent sea at two points was carried out: M Peshnoy and MHP Fort Shevchenko. The results showed that the altimetric data have a high correlation with ground observations (0.89-0.94), with a mean absolute error ranging from 17 cm to 23 cm, and a consistency index above 0.7. The assessment of data applicability according to statistical criteria showed that there are minor deviations. Altimetric data are most accurate for monitoring water levels from April to October and can be used for monitoring sea levels in the open parts of the Caspian Sea. [ABSTRACT FROM AUTHOR]

Situated at the southernmost limits of the late Pleistocene Eurasian permafrost zone, the loess–paleosol sequences of the Lower Volga region contain numerous traces of cryogenesis. Cryogenic features are represented by thin vertical wedges in loess and paleosols, and involutions and wedges in alluvial deposits. Here we describe and interpret four stages of cryogenesis during the late Pleistocene, based on analysis of cryogenic structure morphology, morphoscopy of quartz grains, and micromorphology of subaerial sediments, in addition to calculation of the Cryogenic Weathering Index and a new luminescence chronology derived from published ages. These stages differ in type and distribution of cryostructures and formed in different paleogeographic conditions. Stage I, dated 95–90 ka (Marine Isotope Stage [MIS] 5b), is characterized by the existence of continuous permafrost in northern part of the Lower Volga valley. Stage II (75–70 ka, MIS 5a/MIS 4) is characterized by dry and cold conditions and widespread permafrost. During stage III (52–45 ka, MIS 3b/c), the permafrost was thin and of sporadic distribution. Stage IV (37–35 ka, MIS 3a) is characterized by thin and rare sporadic permafrost. The processes of cryogenic transformation of sediments in the region during these stages took place under both permafrost and seasonal frost conditions. The results obtained significantly improve current understanding of the extent of the permafrost in the south of the East European Plain during the late Pleistocene. [ABSTRACT FROM AUTHOR]

Copyright of Athenaeum: Polskie Studia Politologiczne is the property of Faculty of Political Science & Security Studies Nicolaus Copernicus University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The COVID-19 pandemic’s disruptions to human activities prompted serious environmental changes. Here, we assessed the variations in coastal water quality along the Caspian Sea, with a focus on the Iranian coastline, during the lockdown. Utilizing Chlorophyll-a data from MODIS-AQUA satellite from 2015 to 2023 and Singular Spectrum Analysis for temporal trends, we found a 22% Chlorophyll-a concentration decrease along the coast, from 3.2 to 2.5 mg/m³. Additionally, using a deep learning algorithm known as Long Short-Term Memory Networks, we found that, in the absence of lockdown, the Chlorophyll-a concentration would have been 20% higher during the 2020–2023 period. Furthermore, our spatial analysis revealed that 98% of areas experienced about 18% Chlorophyll-a decline. The identified improvement in coastal water quality presents significant opportunities for policymakers to enact regulations and make local administrative decisions aimed at curbing coastal water pollution, particularly in areas experiencing considerable anthropogenic stress. [ABSTRACT FROM AUTHOR]

In this article, we studied the upwelling phenomena observed in the surface waters of the Caspian Sea. Studying upwelling is crucial for understanding and managing the complex interactions between the ocean, climate, and marine life, with implications for both environmental conservation and human well-being. To accomplish this, we utilized data from MODIS-Aqua satellite observations in the infrared range of 11 microns. These observations had a spatial resolution of 4 km and covered the period from 2003 to 2021. The data was accessed through the NASA Giovanni online data system databases. Our findings indicate that upwelling phenomena are primarily observed in the eastern part of the Middle and South Caspian from May to September. The most intense upwelling occurs along the eastern coast of the Middle Caspian in July and August. Based on long-term averaged data, the upwelling phenomenon is typically observed between 40-44° latitude during this period. The width of the upwelling zone increases gradually from north to south, extending approximately 60-70 km towards the Kazakh Gulf before decreasing towards the south. In the upwelling zone, the temperature gradient can at times reach 4.0°C per 100 km. In certain years, the upwelling zone that initially forms along the eastern coasts can extend over long distances and even reach the western coasts. Generally, the upwelling phenomenon occurs alongside the advection of warm waters from the South Caspian towards the Middle Caspian. [ABSTRACT FROM AUTHOR]

In this study, spanning from 1938 to 2020, the hydrological changes in the Volga River and their repercussions on the Caspian Sea level were examined. Analysis reveals a correlation between high Volga River runoff and increased atmospheric precipitation in its basin. However, in recent years (2005–2020), a significant decline in the runoff coefficient at the Verkhneye Lebyazhie hydrological station, attributable to climate warming surpassing global temperature anomalies, has been observed. This warming's impact on river flow and sea level was quantified, resulting in a 133 cm decrease in sea level from 1977 to 2020. Notably, while, historically, Caspian Sea level changes mirrored Volga River runoff fluctuations until 2005, since 2006, the sea level has markedly dropped, decoupling from river runoff variations. Comparison with recent studies suggests that altered wind characteristics over the Caspian Sea, influencing surface evaporation, may have significantly contributed to this rapid sea level decline in recent years. [ABSTRACT FROM AUTHOR]

This study examines the characteristic of microplastics (MPs) in sediments collected was conducted to examine from the coastal areas of the southern Caspian Sea, Mazandaran province (Babolsar and Sari cities). Twelve sites for sediment sampling selected during 2022. MPs identification detected primarily under stereomicroscope and then ascertains and discovers their polymer composition by ATR-FTIR. The results showed that Babolsar areas, with 5 meters far from the shoreline, had the most abundance (660±165.15 items/Kg). On the other hand, Sari station with 500 meters far from the shoreline contained the least MPs (220±81.33). Average number of detected MPs in all samples was 406.66±161.33. Fibers (80.33%) were the most abundant MPs, whereas films (3.28%) detected the least. In the case of size, the range of 1000-3000 µm showed the most abundant MPs (39.34%) and MPs less than 2 µm the least ones (4.10%). Gray and black (50.82%) was the dominant color and yellow (3.28%) was rarely detected color (3.28%). Polymer constituent of examined MPs includes: (PET: 30%); (PS: 20%); (PA: 20%); and (PP: 15%). The findings of this study revealed that MPs occurrence in coastal sediments derived from several sources; including tourism as well as wastewaters and packaging. These activities cause entering plastic litters along the coastal areas and their degradation accelerated t MPs distribution. [ABSTRACT FROM AUTHOR]

This study used a dynamic model to predict the fishing status of the Persian Sturgeon (Acipenser persicus) along the coast of the Golestan province in the Caspian Sea. The findings indicated that based on the initial population in 2017 equal to 2500 samples of fish if harvested at the current rate, the stocks of this valuable sturgeon fish will be extinected in the next 50 years. However, when considering the harvest rate of 0.2 per year (nearly half of the current catch), the amount of fish harvested will increase so that this stock will completely regain its ability to regenerate itself. [ABSTRACT FROM AUTHOR]

Numerous studies show that species identification of representatives of the genus Alosa using various genetic markers is often difficult and the search for more specific biomarkers is required. For the first time we analyzed polymorphism of COI gene fragment of mitochondrial DNA of two representatives of this genus (A. tanaica and A. kessleri), supplemented with new data on A. immaculata, from the waters of the Ponto-Caspian basin in comparative aspect with other representatives of the herring (Clupeoidea) genera Alosa, Clupea, Clupeonella, Sprattus, and Sardinops. The main result was the conclusion that within the genus Alosa, it is not possible to identify species using the marker used. On the one hand, specimens collected from morphologically distinct individuals and identified as different species have the same haplotypes. On the other hand, samples belonging to different species differ from each other by an insignificant number of nucleotide substitutions and do not form independent clades on the phylogram and haplotype network. This indicates the absence of genetic differentiation between the studied samples of herrings of genus Alosa into separate species and species groups when using DNA barcoding based on the COI gene. The reasons for such a phenomenon may be the following: (1) incorrect identification of species in catches, since shads (Alosidae) have high morphological flexibility and in many species, the main external morphological characters often overlap; (2) recent time of speciation by the standards of biological evolution for shads of genus Alosa; (3) difference in proportion of interspecific hybrids, which can vary significantly between populations of the same species. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced plastics (GFRPs) have been widely used in marine structures, recently. In this paper, the water absorption and compressive behaviour of pultruded fiber-reinforced plastic pipes (GFRPs) after immersion in Caspian sea water and distilled water for 1, 7, 14, 21, 28, 35, and 40 days is experimentally investigated. In this respect, the specimens are submerged in Caspian seawater and distilled water and then their water absorption rate, length, and their compressive strength were measured every day. The compressive mechanical properties of the specimens in the as-received and water-aged states are obtained using quasi-static compression tests. The amount of water absorption and length change due to immersion in these two cases have also been investigated. After 40 days, the average relative humidity absorption of the samples in Caspian Sea water and distilled water were 2.88% and 2.89%, respectively. It was observed that after immersion in both Caspian Sea water and distilled water, the final compressive strength and absorbed energy of the pultruded pipes increased. [ABSTRACT FROM AUTHOR]

Introduction: The Caspian Kutum (Rutilus frisii) is one of the most important bony fish species of the Caspian Sea and has high conservation and commercial value. There were decreasing trends in its catch levels in the last years. Identifying temporal trends of its catch could help adopt proper plans to maintain the stocks of this important species and achieve sustainable exploitation goals. In the present study, we conducted a time-series analysis for catch data of the species over a decadal period. Material and Methods: The commercial catch data of Caspian Kutum, over the seine net fishing points of the northern coastal regions of Iran during catch seasons 2002/03 to 2011/12, were used as catch-per-unit-of-effort (CPUE). A 5-point moving average of CPUE was used to distinguish the fishing points as optimum (with normalized CPUEs ≥ 0.6) and non-optimum (with normalized CPUEs < 0.6) fishing locations. Time series modeling was conducted using the seasonal autoregressive integrated moving average (SARIMA) model based on seasonal 3- month intervals. The performance and predictive ability of the models were assessed using a set of indices, including Akaike’s information criteria (AIC), Bayesian information criterion (BIC), root mean squared error (RMSE), normalized root mean squared error (nRMSE), mean absolute error (MAE), normalized mean absolute error (nMAE) and the Pearson correlation coefficient (r). CPUE trends over the five years of 2013 to 2017 were predicted using the bestfitted SARIMA models. Results and Discussion: Five optimum (HR) and six non-optimum ranges (CR) were identified over the whole fishing points range (WR). The fitted SARIMA models based on the whole data of all fishing locations as well as classified optimum and non-optimum ranges of fishing locations did not have significant non-seasonal autoregressive and moving average components, indicating no increasing nor decreasing trends for CPUE over the study period, while for some of the ranges of fishing points, there were significant autoregressive and moving average components with clear seasonal increasing trends. The overall trend of CPUEs showed mainly an increase from 2002 to 2006, and then after relatively constant levels, there were decreases from 2009 to 2013. The obtained predictions from the models for data sets having sudden temporal fluctuations were less accurate. In contrast, higher accuracy levels of predictions and trends were observed for fish catch time series with no sudden alterations in CPUE levels over the studied period. Most of the obtained predictions for 2013-2017 similarly presented stationary fluctuation trends with apparent seasonal increases in CPUEs. Conclusion: Time-series modeling for R. frisii using the SARIMA method mainly indicated clear increasing seasonal trends without any general trend of change over the whole fishing points. The simplicity of the obtained models considering the obtained seasonal and nonseasonal components could be explained by the short time frame and the low number of data points. However, spatial classification of fishing points resulted in more detailed models and higher recognition potential of them. The findings of this research could lead to a better understanding of the temporal trends in catch levels of Caspian Kutum and use them by fisheries managers to adopt efficient management plans regarding the available stocks of this species in the future. [ABSTRACT FROM AUTHOR]

We investigated the abundance and distribution of the invasive ctenophore, Mnemiopsis leidyi, at five transects in the southern part of the Caspian Sea for four seasons from December 2019 to August 2020. M. leidyi was found in all transects and seasons. The maximum temperature was around 27.5 °C in summer. The highest abundance and biomass of M. leidyi were found in the T5S1 (Larim transect) and T2S1 (Kiashahr transect) stations in summer (120 ± 22 ind m−3 and 279 ± 46 mg m−3) and the lowest in T1S3 and T1S2 stations (Lisar transect) in winter (3 ± 1 ind m−3 and 0.04 ± 0.01 mg m−3), respectively. Furthermore, the maximum average of abundance and biomass of M. leidyi were observed in Larim and Kiashahr transects (106 ± 15 ind m−3 and 242 ± 33 mg m−3) and the minimum in Lisar transect (4 ± 0.6 ind m−3 and 0.05 ± 0.01 mg m−3) respectively. Also, the body lengths that ranged between 0 and 5 mm were the most frequently observed. The highest total abundance and biomass of the M. leidyi were observed in summer (1033 ind m−3 and 2923 mg m−3) and the lowest in winter (122 ind m−3 and 22.09 mg m−3), respectively. The results of the DistLM showed that the distribution and abundance of M. leidyi in the south of the Caspian Sea are highly related to NO3− and PO43− and to a lesser extent to temperature and Sio2. [ABSTRACT FROM AUTHOR]

Abstract The choice of temporal resolution has high importance in ecological modeling, which can greatly affect the identification of the main drivers of an organism's distribution, considering the spatiotemporal dynamism of environmental predictors as well as organisms’ abundance. The present study aimed to identify the spatiotemporal distribution patterns of Caspian Kutum, Rutilus frisii, along the southern coast of the Caspian Sea, north of Iran, evaluating multiple temporal resolutions of data. The boosted regression trees (BRT) method was used to model fish catch distribution using a set of environmental predictors. Three temporal scales of data, including seasonal, sub‐seasonal, and monthly time frames over the catch season (October–April), were considered in our modeling analyses. The monthly models, utilizing more detailed data scales, exhibited the highest potential in identifying the overall distribution patterns of the fish, compared to temporally‐coarse BRT models. The best models were the BRTs fitted using data from March and April, which represented the final months of the catch season with the highest catch levels. In the monthly models, the main determinants of the Kutum's aggregation points were found to be dynamic variables including sea surface temperature, particulate organic and inorganic carbon, as opposed to static topographic parameters such as distance to river inlets. Seasonal and sub‐seasonal models identified particulate inorganic matter and distance to river inlets as the predictors with the highest influence on fish distribution. The geographical distributions of fish biomass hotspots revealed the presence of a stable number of fish aggregation hotspot points along the eastern coast, while some cold‐spot points were identified along the central and western coasts of the Caspian Sea. Our findings indicate that utilizing fine time scales in modeling analyses can result in a more reliable explanation and prediction of fish distribution dynamics. The investigated approach allows for the identification of intra‐seasonal fluctuations in environmental conditions, particularly dynamic parameters, and their relationship with fish aggregation.

The coastal and estuarine wetlands of the northern Caspian Sea, which borders southeast Russia, provide support for millions of waterfowl and shorebirds during nesting, molting, migration, and wintering periods (1,2); [...]

With the rapid development of aeromagnetic (primarily uncrewed) methods for measuring the magnetic field, the possibility of detailed magnetic research in hard-to-reach mountainous areas, forested areas, swamp areas, desert areas, and water areas has emerged. The conditions for interpreting the magnetic field are most difficult due to the vector nature of the magnetic properties of rocks, the wide range of their properties, and the presence of residual magnetization. The physical and geological conditions of the territory of Azerbaijan are characterized by rugged terrain relief, inclined magnetization (~58°), and complex geological environments. Along with using a probabilistic approach, deterministic methods for solving inverse and direct problems of geophysics become of great importance since it is possible to identify relatively extended reference boundaries and analyze magnetic anomalies from separate bodies of relatively simple shape. The article briefly outlines the main stages of processing and interpreting magnetic data under complex environments. The theoretical examples discussed include a block diagram of various disturbances, interpretive models of thin and thick beds, an intermediate model, a thin horizontal plate, and a horizontal circular cylinder on the flat and inclined surfaces under inclined magnetization conditions. The process of assessing magnetization on sloping terrain relief is shown. The presented field examples for the Caucasus Mountains show the quantitative interpretation of aeromagnetic data at the Big Somalit and Guton sites (southern Greater Caucasus, Azerbaijan), a deep regional profile through the Lesser and Greater Caucasus, magnetic field studies in the area around the Saatly superdeep borehole (Middle Kur depression between the Greater and Lesser Caucasus), and 3D magnetic field modeling at the Gyzylbulag gold deposit (the Azerbaijani part of the Lesser Caucasus). In the Caspian Sea, we demonstrated the use of an information parameter to identify faults in the Bulla hydrocarbon field (Gulf of Baku) and, for the first time, obtained the relationship between the generalized aeromagnetic data (2.5 kilometers over the mean sea level) and the central area of the mud volcanoes distribution in Azerbaijan.

To determine the hydrophysical and hydrochemical parameters of sea water and their changes during dredging works in the north‐eastern part of the Caspian Sea along the Western Approach Route and near/inside block D, islands EPC‐2, EPC‐3, EPC‐4 and island A of the Kashagan field.Measurement of hydrophysical parameters: salinity, temperature, turbidity, dissolved oxygen concentration, electrical conductivity, pH of seawater was carried out using a portable multi‐parameter analyser "Horiba‐U53" directly in the water column. Water transparency was determined using a Secchi disc. The depth of the water layer was determined using a sounder. Hydrochemical investigations were carried out for seven parameters, with all components sampled in the near‐surface and benthic horizons. Water samples were taken using probes or bathometers: BM‐48, GR‐18 or their analogues.Hydrochemical analyses of seawater samples for: biogens (NO2, NO3, NH4, Ntotal, and Ptotal), synthetic surfactants, phenols, hydrocarbons including polyaromatic hydrocarbons (PAHS), heavy metals, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). These were carried out in laboratory conditions using analytical equipment according to scientifically accepted methods.The data obtained as a result of the research allow us to draw the following conclusion: changes in the amount of suspended sediment in sea water lead to changes in physical and chemical properties of water (increase in turbidity, disturbance of sediment composition and properties), changes in biotopes, deterioration of oxygen regime, optical properties of water and temperature regime.

The article presents the author's insight on the reasons for the emergence of the city in the Volga delta in Khazar period. The main reason is declared the necessity of transshipment of goods from sea ships to river boats during trade along the Caspian-Volga trade route. The changes in the routes of movement of goods along the Volga route in the VIII–IX centuries (by passing the Volga delta) and in the X century (via the Volga delta) due to a change of starting point of these routes – Damascus in the early period and Baghdad in the late period, are traced. The second reason for the emergence of the city in the Volga delta is the presence here of the nomadic headquarters of the Khazar Khagans, whose name in Russian sounds like “Belaya” (White). Associating this name with the color designation of the cardinal points in Turkic culture, the author suggests that initially the “White” or Western headquarters as the center of Khazaria corresponded to the Western headquarters of the Turkic Kaganate. Thus, the political continuity of Khazaria in relation to the Turkic Kaganate is declared. It is suggested that the original location of the “White” headquarters corresponds to the vicinities of the village of Semibugry in the central part of the Volga delta, and its transformation into a full-fledged city can be traced archaeologically at the Samosdelka settlement in the western part of the delta, where it was moved in the X century as a result of the Caspian transgression.

Polychlorinated Biphenyls (PCBs) are mutagenic, carcinogenic, and persistent organic pollutants of the marine and coastal environment. No previous research has precisely used barnacles as potential PCBs bioindicators in the Caspian sea. The present survey was done to add the PCBs concentrations amongst the barnacle and sediment samples collected from 5 important Iranian ports besides the Caspian sea. Barnacle and sediment samples were collected from Astara, Anzali, Caspian, Kiashahr, and Chamkhaleh ports. Samples were transferred to the laboratory and analyzed for the presence and concentration of PCBs using GC-MS. Eighty different types of PCB were detected in the examined samples. PCBs concentration ranged from 02.00±00.10 to 53.00±00.60 ng/g. PCB-77 (53.00±00.60 ng/g in Chamkhaleh, 53.00±01.20 ng/g in Caspian, 53.00±02.40 ng/g in Anzali, and 53.00±2.7 ng/g in Astara ports) had the highest concentration in barnacle samples. PCB-52 (53.00±00.70 ng/g in Chamkhaleh port) had the highest concentration in sediment samples. PCB-114 had the lowest concentration amongst the barnacle (02.00±00.10 ng/g in Astara port) and sediment (03.00±00.20 ng/g in Anzali port) samples. This study is the first report evaluating the presence and concentration of PCBs in barnacle in the Caspian Sea. The role of barnacles and sediments as biomonitors of PCBs was determined. It seems necessary to set strict rules to prevent pollutants from entering the Caspian Sea. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to assess the environmental capacity of the southern Caspian Sea to develop Agritourism in rural areas of Guilan, Mazandaran, and Golestan provinces. Agritourism is considered a service activity in providing currency and income for rural communities and is an economic strategy. Research Method: The present study is applied in terms of purpose and descriptive-analytical in terms of approach. Secondary data analysis was used to assess the agricultural situation and field data were used in the field of environmental landscape, human activities, and infrastructure. Data were collected and monitored, encoded, and analyzed in an SPSS environment. Findings: The results indicate that -- according to the maps drawn in the field of agricultural products in these three provinces and to the opinions of relevant experts -- Guilan Province, with an average of 3.47 in relation to the formation and development of Agritourism from the situation, is the best; Golestan Province, with an average of 3.38, is the next; and finally, with a very small difference, Mazandaran Province with an average of 3.24, is in the third place. As a result, the southern part of the Caspian Sea, especially its rural areas, is suitable for the development of agritourism. Research Limitations: The main challenges in the process of this research are the lack of easy access to experts related to agriculture, tourism and rural issues, as well as the lack of up-to-date statistical data in this field. Originality/Value: This research was conducted for the first time in the southern region of the Caspian Sea and could pave the way for further research. [ABSTRACT FROM AUTHOR]

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The Caspian Sea as the largest lake in the world is very important from the different aspects of economic, social, tourist, and environmental. In this regard, monitoring the water quality of the southern shores of the Caspian Sea has a special importance in order to study it according to national and international standards and control the possible pollution of the coastal strip of Iran. Therefore, the National Research Center of Caspian Sea was analyzed and checked the quality of water in terms of amount heavy metal by establishing 14 stations in the coastal strip from Miankala to Astara. In this study, the concentration of heavy and dangerous metallic and non-metallic elements in depth 1 and 7 meters from Farah Abad station to Lisar and at two depths of 1 and 4 meters in Miankala and Astara stations were measured by ICP-MS method and heavy metal evaluation index, pollution degree index, heavy metal pollution index and Spearman's correlation coefficient were calculated according to the concentration data. The obtained results show that the average concentration of heavy and dangerous metals B(2.37ppm), Ba(24.9ppb) and Zn(18.3ppb) at a depth of one meter and B(2.44ppm), Zn(26.5ppb) and As(17.5ppb) at a depth of seven meters are the highest concentrations recorded in the monitoring stations. According to the data, the highest value of the HEI(1.58), the Cd(-5.96) and the HPI(68.49) of heavy metals were obtained at depth of seven meters in Farah-Abad station and one meter Faridoonkanar and Miankale station, respectively. [ABSTRACT FROM AUTHOR]

The flyways of many different wild waterfowl pass through the Caspian Sea region. The western coast of the middle Caspian Sea is an area with many wetlands, where wintering grounds with large concentrations of birds are located. It is known that wild waterfowl are a natural reservoir of the influenza A virus. In the mid-2000s, in the north of this region, the mass deaths of swans, gulls, and pelicans from high pathogenicity avian influenza virus (HPAIV) were noted. At present, there is still little known about the presence of avian influenza virus (AIVs) and different avian paramyxoviruses (APMVs) in the region's waterfowl bird populations. Here, we report the results of monitoring these viruses in the wild waterfowl of the western coast of the middle Caspian Sea from 2017 to 2020. Samples from 1438 individuals of 26 bird species of 7 orders were collected, from which 21 strains of AIV were isolated, amounting to a 1.46% isolation rate of the total number of samples analyzed (none of these birds exhibited external signs of disease). The following subtypes were determined and whole-genome nucleotide sequences of the isolated strains were obtained: H1N1 (n = 2), H3N8 (n = 8), H4N6 (n = 2), H7N3 (n = 2), H8N4 (n = 1), H10N5 (n = 1), and H12N5 (n = 1). No high pathogenicity influenza virus H5 subtype was detected. Phylogenetic analysis of AIV genomes did not reveal any specific pattern for viruses in the Caspian Sea region, showing that all segments belong to the Eurasian clades of classic avian-like influenza viruses. We also did not find the amino acid substitutions in the polymerase complex (PA, PB1, and PB2) that are critical for the increase in virulence or adaptation to mammals. In total, 23 hemagglutinating viruses not related to influenza A virus were also isolated, of which 15 belonged to avian paramyxoviruses. We were able to sequence 12 avian paramyxoviruses of three species, as follows: Newcastle disease virus (n = 4); Avian paramyxovirus 4 (n = 5); and Avian paramyxovirus 6 (n = 3). In the Russian Federation, the Newcastle disease virus of the VII.1.1 sub-genotype was first isolated from a wild bird (common pheasant) in the Caspian Sea region. The five avian paramyxovirus 4 isolates obtained belonged to the common clade in Genotype I, whereas phylogenetic analysis of three isolates of Avian paramyxovirus 6 showed that two isolates, isolated in 2017, belonged to Genotype I and that an isolate identified in 2020 belonged to Genotype II. The continued regular monitoring of AIVs and APMVs, the obtaining of data on the biological properties of isolated strains, and the accumulation of information on virus host species will allow for the adequate planning of epidemiological measures, suggest the most likely routes of spread of the virus, and assist in the prediction of the introduction of the viruses in the western coastal region of the middle Caspian Sea. [ABSTRACT FROM AUTHOR]

There are various strong ties such as language, ethnicity, religion and culture between Azerbaijan and Turkmenistan, located on the eastern and western shores of the Caspian Sea. However, despite these ties, the relations between the two states were not always positive, had ups and downs in certain periods, and even ties reach breaking point. Particularly, disputes about who owns the energy resources in various fields in the Caspian Sea have negatively affected relations. Since 2014, there have been various developments in the relations between Azerbaijan and Turkmenistan, which are important actors of the Turkish world. Different factors are effective in the rapprochement between Baku and Ashgabat. The study examines the factors that positively affected the relations between the two states in the post-2014 period. [ABSTRACT FROM AUTHOR]