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This study evaluates changes in species composition, catch, and CPUE of three species of kilkas in the Caspian Sea from 1961 to 2009. The effects of fluctuations in sea level rise and fall on the catch of kilka as well as the impacts of a recent invasion by Mnemiopsis leidyi (Ctenophora) were assessed in terms of species composition and CPUE of kilkas in the Iranian coastal region of the Caspian Sea. We found a negative correlation between long-term sea level changes and total catch (R2 = –0.56; P<0.001, which significantly declined in 1995 when the sea level increased to its highest level. Comparing catch per unit effort (CPUE) values during the pre-invasion (1996–1999) and post-invasion (2000–2009) periods indicated significant declines in anchovy and bigeye kilka, while common kilka increased significantly after the ctenophore invasion. During 2000–2009 overfishing, together with various environmental impacts following the introduction of Mnemiopsis, were major factors that contributed to changes in species composition and the collapse of kilka stocks in the Caspian Sea.

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We measured the impacts of coastal modification on beach erosion and beach retreat conditions, selecting the Miankaleh Region as an example of a complex high-pressure free zone with high levels of engineering and tourism activity. Nine sampling transects, stretching from the shoreline to a 10 meter depth, were defined and 36 sediment samples were collected from the sea bed at depths of 1, 3, 5, and 10 m. After conducting laboratory tests, data were analyzed in terms of sediment dynamic parameters such as grain size, sediment size distribution, mean, median, skewness, kurtosis, standard deviation, and mineral composition. Beach structure and morphodynamic conditions were assessed in the Miankaleh region, by means of satellite image interpretation and field surveys. Results show that from 1978 until the present the average rate of beach retreat rapidly increased due to sea level rise and coastal constructions that have resulted in a progressive increase in sea level height in this region. Erosion vulnerability hazards have also increased in the eastern part of the study area and deposition processes have developed in the western Amirabad region.

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Mnemiopsis leidyi population activities first were recorded during the coastal observations in 2001 in which its population considerably increased afterward and now sustained the southern Caspian Sea. Maximum summer-autumn M. leidyi abundance was recorded in euphotic layer in 2002 (851±85 ind.m^-3) and maximum biomass was in 2001 with 48.1±14.4 g.m^-3) while minimum were in aphotic layer. In years 2003 to 2011, M. leidyi abundance and biomass sharply declined to 1-843 ind.m^-3 and 0.07-37.7 g.m^-3, respectively. The length-frequency distribution of Mnemiopsis showed larval, juveniles and transitional stages that made up 98.6% of the total population. In the southern Caspian Sea, Acartia tonsa was the highest number of mesozooplankton species (36 species) which decreased tenfold after Mnemiopsis invasion during 2001-2010. Fecundity experiments of Mnemiopsis showed the average of 8 eggs. day^-1, with a maximum of 35 eggs.day^-1which increased with increasing body length. The main food was larger amounts of zooplankton prey such as copepodites and adult of A. tonsa. It seems the sharp decreased of Mnemiopsis abundance could be related the decreasing of ova reproduction; and food ability is the main reasons of M. leidyi sustained in the southern Caspian Sea. The objective of present study was to provide information about parameters influencingthe M. leidyi decreased after initial bloom invasion in the southern Caspian Sea.

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There are a number of ideas to generate cloud and precipitation in the southern coasts of Caspian Sea, but none of them explain the cause of precipitation particularly heavy and super heavy precipitations precisely. This study describes main thermodynamic factors when the situation and location of synoptic patterns are effective. On the basis of daily data, monthly regimes and monthly trends of the Sea Surface Temperature (SST), difference between 2m air temperature and SST over the Caspian Sea as well as the SST gradients in different distances on latitude and its anomaly were calculated. For recognition of synoptic conditions, humidity advection, geopotential and sea level pressure maps were drawn. The results showed that there are three thermodynamic factors over the Caspian Sea to produce precipitation particularly from September to December. The first factor is arrangement and well organized of the SST gradients as it decreases from the south to the north of Caspian Sea. Also, the SST over the Sea must be enough warm to produce clouds and precipitation. The last factor is the difference between 2m air temperature and SST. When the synoptic patterns in different pressure levels are suitable for instability, the air-sea interaction process is the most important factor to produce the advection humidity, clouds and precipitation particularly heavier precipitation events in the north of Iran.

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Factors affecting the spatial variations of water quality of the Mazandaran coastal ecosystem was determined in summer 2012. For this purpose, water quality parameters (nutrients, temperature, conductivity, salinity, dissolved oxygen, pH, chlorophyll α and turbidity) were evaluated along 4 transects (Amirabad, Babolsar, Noshahr and Ramsar) in the depths of 5, 10, 20 and 50m, using multivariate analysis methods.  Based on the cluster analysis of data, the sampling sites could be classified into 5 distinct groups, including 35-50m water layer of station 50m in all transects, 0-5m layer in station 5m in all transects, Ramsar transect and the majority of surface and bottom layers of 3 transects including Noshahr, Babolsar and Amirabad. Based on discriminant analysis, 86.40% of the sampling sites were correctly classified. Factor analysis explained 87.53% of the total variance, the five principal components of which (viz. temperature, turbidity, nitrate, silica and ammonium) were considered as the most effective parameters on the spatial variation of water quality. This study suggests that the number of sampling locations can be reduced to two transects. Thermocline, transport of nutrients (specially phosphorus and ammonium) from rivers, sea floor, cage culture and the ctenophore, M. leidyi, were the most effective sources on spatial variations of water quality. Moreover, the multivariate statistical methods were found to be useful tools to recognize the spatial variations pattern along the Mazandaran coasts in summer.

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 Length-weight relationship, age range and fecundity of 40 specimens of the Russian sturgeon, Acipenser gueldenstaedtii, collected from two fishing stations in the southeastern Caspian Sea, were determined. Average length (TL) and weight were 129.5 cm and 12.7 kg for males and 145.8 cm and 22.15 kg for females, respectively. Absolute fecundity was 184000 in average and condition factor calculated 0/58 and 0/7 for male and females, respectively. Average age for males and females was 12.7 and 14.6 years, respectively. All these factors were lower than previous records from the Volga river estuary. Length-weight relationships results demonstrated isometric growth pattern with average slope of 2.978 and 2.822 for males and females respectively. These values were not statistically different between sexes (p> 0.05), but using this relationships for each sex separately will be useful for more reliable results especially in broodstock studies.

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Length-weight relationships and fecundity of 93 individual female Acipenser persicus broodstocks were investigated. The specimens were caught during 2001-2005 from Golestan, Mazandaran and Guilan provinces along the southern coast of the Caspian Sea. Total length and weight of each fish was measured to the nearest 1cm and 100 g, respectively. Age determination was carried out by using transects of the first ray of pectoral fin. The absolute fecundity was assessed by egg count per weight unit of all eggs existed in the body. The specimens were from 13 to 20 years old, of which the 16 years old had the highest proportion with 23.7%. Range of total length and weight were 132.5 to 211 cm and 14 to 42 kg, respectively. Mean absolute fecundity was estimated 267810 ± 92570. Total length, weight and absolute fecundity of fish increased with age in all cases, showed a significant positive correlation (p <0.01). The slope of the length-weight relationship (b) was equal to 2.745 and isometric growth pattern was determined in this species.

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World production of caviar from the farmed sturgeon has recently so increased that in addition to compensate reduction of natural resources of sturgeon, it has also increased its share in the world market for caviar and its substitutes. Although Belarus, China and Norway are currently considered as the main exporting countries of caviar and its substitutes but, Iran solely exports caviar from sturgeon species. Having a world reputation in caviar brand, as well as the decreased natural resources, Iran aims to develop sturgeon rearing as well as modern marketing along with global standards to stand its brand and reputation as well as its world market share. The present paper reviewed the caviar and caviar substitutes market with emphasis on sturgeon caviar. During 1991-2013, caviar export from Iran decreased by 21.2 % in quantity and decreased income by about 17.2 %. However, the caviar value increased from 231000 to 680000 USD per ton.

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Samples from five sturgeon species including Persian sturgeon (Acipenser persicus), Russian sturgeon (A. gueldenstaedti), Great sturgeon (Huso huso),Ship sturgeon (A. nudi-ventris) and Stellate sturgeon (A. stellatus) were collected from the South Caspian Sea. DNA was extracted from the fins, eggs and skeleton muscle of the five species. RAPD markers were used for identifying different kinds of black caviar and sturgeon meat. The polymorphic band from RAPD amplification of DNA from two out of five sturgeon spe-cies was purified, cloned and sequenced. RAPD analysis was carried out in order to com-pare the five species using an operon primer set. Sequence Characterised Amplifed Re-gion (SCAR) primers were designed and used to amplify caviar DNA from five sturgeon species. A marker of potential economic importance was discovered that is able to distin-guish three species from caviar and also to distinguish Ship sturgeon caviar from osetra caviar (from Russian and Persian sturgeon) and also other species. This marker could as-sist international conservation and legal efforts to save what is left of the commercial Ship sturgeon populations which are endangered and whose caviar is at present substituted for the more expensive osetra caviar.

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 The changes of biodiversity, indicator species (IS) and catch per unit effort (CPUE) of bony fishes in beach seines in Iranian waters of the Caspian Sea during 1996 to 2012 was investigated. Among the catch of 14 species/groups, kutum and mullet comprised 56.78% and 31.81% of the total catch. Minimum and maximum CPUE were 158.5±9.1 and 344.9±31.2 kg/haul and Shannon diversity was 0.57±0.02 and 0.92±0.02, respectively. There were significant differences in community composition of fishes in beach seines among three seining times (morning, afternoon and night time), three seining periods (1996-2000, 2000-2005 and 2005-2012), three regions (west, middle and east), and different seasons (in all cases MRPP, p<0.001). During 1996-2000, Rutilus rutilus, Vimba vimba, Chalcalburnus chalcoides, Aspius aspius, Barbus sp., Salmo trutta caspius and, Silurus glanis in the years 2000-2005 species/groups shads, Abramis brama and Esox lucius and in the years 2005-2012 species Cyprinus carpio and Stizostedion lucioperca were indicator species. Also, in the west region of the Caspian Sea species/groups V. vimba, C. chalcoides, A. aspius, Barbus sp., A. brama,S.lucioperca,E.lucius and S. glanis; in middle Rutilus frisii kutum, shads and S. trutta caspius and in east species/groups mullets, R. rutilus and C. carpio were identified as indicator species.

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In recent decades, due to fluctuations in sea levels, environmental pollutions, and invader species invasion, the ecosystem of the Caspian Sea has been changed. In this study, assessing impact on ecosystem functiuons was conducted according to the new invader species (Mnemiopsis leidyi) by using commercial catches during three periods: 1996-2000, 2001-2006 and 2007-2011; in three phases of the invasion: establishment, expansion and adjustment, respectively. The results showed that in the three periods the average of catch of bonyfish were 15700.0±1993.2, 18430.8±3857.6 and 19176.6±1579.6 mt which was no significantly different among them (p>0.05) but the catch of kilkas (75080.0±16171.7, 25129.5±10441.5 and 21105.2±5199.2 mt, repectively) and sturgeons (1010.2±242.8, 385.5±264.3 and 51.8±19.9 mt, respectively) declined sharply and were significantly different among them (p<0.05). During three periods, ecosystem functions had a wide ranged change. The ecosystem functions were shifted E0 (No impact) in first period to E2 (moderate impact) and E3 (strong impact) in the second and third periods. Loss functions of two keystone species (anchovy and bigeye kilka) can be one of the resesons of sharp decline in upper layer of food web chain, i.e. sturgeons and Caspian seal in the Caspian Sea.  

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Aims This study was conducted to determine the Exotic fish food strategy of rainbow trout escaped from cultivating cages located in the southern basin of the Caspian sea (Mazandaran).
Materials & Methods A total of 90 specimens of this species were collected during the period from September 2017 to may 2018 from bony fish from west to central coast of Mazandaran. Sample of fish were biomediated and the age was determined by scales and operclum.
Findings The relative frequency of food items were Balanus glandula , Clupeonella cultriventris , Cerastoderma lamarcki, Neogobius fluviatilis،  Atherina caspia ،Chelon saliens ، Chinavia hilaris  ، Taxiphyllum barbieri ، Rutilus kutum، Cumacea،  Syngnathus  caspius  and  Gasterosreus aculeatus respectively. The result showed that a wide range of food was more central than the west, the fullness index in the female was more than male and in age groups older than 2 ⁺ and 3 ⁺ is more than 1 ⁺ (P>0.05). The fullness index, especially in the spring, increased significantly, the presence of B.glandula  more than C. cultriventris, but its relative importance was less than C. cultriventris (P> 0.05). 
Conclusion This fish has a carnivorous behavior and uses a wide range of foods, so it is possible to compete with many species of Caspian sea fish such as Salmo caspius. The effects of the adaptations and behavioral, physiological and ecological mechanisms of C. cultriventri and B.glandula  were more important in fish feeding.

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Aims: This research aimed to evaluate the spatial patterns of water quality and its controlling factors in the Mazandaran coastal ecosystem during winter using the multivariate analysis methods.
Materials and methods: Water quality parameters such as nutrients, temperature, conductivity, salinity, DO, pH, chlorophyll-a and turbidity were measured monthly in 16 stations (44 layers) along 4 transects (Amirabad, Babolsar, Noushahr and Ramsar). To evaluate the data, several multivariate statistical methods were used including discriminant function analysis, cluster and factor analysis as well as correlation test.
Findings: Results of cluster analysis showed that the sampling sites (44 layers) were classified into 4 groups. Based on discriminant analysis, 93.20% of the sampling sites correctly classified. Factor analysis extracted 4 principal components that explained 74.05% of the total variance. Based on these analyses, organic phosphorus, organic nitrogen, turbidity, chlorophyll-a and temperature were the most effective parameters on the spatial variation of water quality.
Conclusion: This study suggested that the number of sampling locations could be reduced to 3 transects including Amirabad, Babolsar and west coasts (Noushahr and Ramsar) and 2 stations (one surface layer and one deep layer). Transport of nutrients from land, sea floor and fish cage culture were the most effective factors on spatial patterns of water quality in Mazandaran coasts. Based on the results, multivariate statistical methods are also introduced as one of the useful methods for identifying the spatial pattern of water quality.

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Aims: In the present study, a three-dimensional numerical hydrodynamic model with the capability to simulate the diffusion of chemical pollutants released in marine basins was developed and used as a case study to simulate the diffusion of phosphate released by fish culture cages located in the Sisangan marine basin.
Materials & Methods: The equations of the model including momentum equations, continuity of mass equation, temperature, salinity, representative of vertical velocity, the tendency of bottom pressure equations and an extra three-dimensional advection-diffusion equation for simulation of pollutant’s diffusion rewritten in the earth’s spherical coordinates with a vertical Sigma coordinate were solved using finite difference method. To provide the open boundary conditions, the model was used for simulation of wind driven currents in the Caspian Sea from 20 October 2018 to 20 May 2019. For the application of wind field and real geometric condition, it was used the time series of wind fields supplied by ECMWF reanalysis dataset and GEBCO bathymetry with 0.125 degrees resolution and 15 seconds of geographical resolution, respectively.
Findings: Considering the concentration of 17ppb for the phosphate as a concentration of pollutant in the source of the pollution in the location of the fish culture cages, wind induced currents and the diffusion of the phosphate were simulated for 8 months in both horizontal and vertical directions. The results of the simulations were demonstrated and analyzed within the framework of the horizontal surface current, distribution of the phosphate’s concentration in both horizontal and a vertical latitude-depth cross section.
Conclusion: The phosphate’s diffusion is affected by the wind induced currents and after 8 months, it could be extended to the distance of 11, 8.5, 9.5, and 5.7 kilometers far from the cages in eastern, western, southern, and northern directions, respectively. With the generation of vertical velocity and the turbulence effects in the upper layers, phosphate might be diffused in the vertical direction up to 400m depth, as well.

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The aim of this paper was to study the time detection for the arrival and initiation of Siberian high pressure activities in southern coast of the Caspian Sea. Therefore, the temperature and pressure data were collected from Anzali, Babolsar and Gorgan stations for the September, October, November and December months during the statistical periods of 1971 to 1980. The criteria for Siberian high pressure current were the presence of the ridge system with the isobar line of minimum 1020hp. in southern coasts of Caspian Sea, along with the establishment of a Siberian high pressure core cell in the eastern longitude of 60○ to 120○ and northern latitude of 40○ to 60○ in the region. Whenever the changes in temperature and pressure of stations occurred simultaneously by a penetration of Siberian high pressure ridge on the region , the time had been registered as the arrival time of Siberian high pressure to the southern coasts of Caspian Sea. Accordingly, the second decade of October (third decade of Mehr) was recognized as the initiative stage of Siberian high pressure activities in the region with the highest frequency of 50% during the statistical period.

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Seasonal variability of different parameters of the water column including chlorophyll-a, dissolved oxygen and turbidity in Noshahr region in Mazandaran province based on measurements using CTD device taken during different seasons of 1397 are investigated. According to the results, maximum chlorophyll-a during the spring in offshore area is below the mixed layer at the depth of 20 (m), during the summer with the lowest concentration among all the seasons is inside the mixed layer at the depth of 20 (m) in offshore area and during the fall and the winter the highest concentration of chlorophyll-a is observed near the coast. Maximum dissolved oxygen during the spring is located at the depth of about 20 (m), in the spring in the offshore is at the depth of 40 (m) and during the fall and winter is observed with maximum values near the surface and the lowest values near the bottom. Maximum turbidity is observed in all seasons near the shore at the depth of 5 m and the maximum values of the turbidity are found during the cold seasons. Zero values of the turbidity during the winter is observed inside the mixed layer, while during the fall and the summer is below the mixed layer and in the spring is found in the deep layer.

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The disappearance of bipolar system following the disintegration of the Soviet :union:, has also changed many strategic concepts. Central Asia, as a part of the Soviet empire, has become an arena for regional and global challenges after these transformations. The region, already faced with various political, economic, social and cultural problems, soon became a location for the activities of Islamic fundamentalists, which in turn intensified regional crisis. Different socio-political problems made the ground for these activities. The basic question of this paper is: What is the role of NATO enlargement and its effects on security provision in Central Asia? This paper tries to answer that, “what role can NATO play in Central Asia in order to provide security in this region specially after September 11th and the following events”. Based on current security issues in Central Asia, America has seriously emphasized on socio-economic reforms under the” Greater Middle East” framework. Central Asian leaders are obliged to control political, social and economic crisis to prevent terrorist acts and reduce public dissatisfaction. Political transformations following the Soviet :union: collapse have clearly revealed that the roots of threat and instability in Central Asia are essentially internal. Sooner or later, leaders of these states have to resolve these threats, based on a clear understanding of regional sociopolitical realities.