جستجوی مقالات مرتبط با کلیدواژه « Caspian Sea » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

This work aimed to investigate the morphological diversity of five species of the genus  Ponticola viz. P. syrian, P. group, P. ironic, P. primary, and P. hircaniaensis (Gobiidae). For this purpose, the specimens of the studied species were sampled from different stations in the rivers of the southern basin of the Caspian Sea in the provinces of Guilan, Golestan, and Mazandaran, and a total of 20 morphometric characteristics were measured. Then, the morphological characteristics after standardization were compared using PCA, Kruskal-Wallis, and CVA analyses. Based on the results, all characteristics showed significant differences. The studied species, except P. iranicus and P. hircaniaensis, were discriminated from each other, and the most important discriminative characters were the height of the second dorsal fin, preanal length, the length of the pectoral fin, the length of the caudal peduncle, the pre dorsal length, ventral fin length, and head length. The members of the genus Ponticola are similar in terms of morphological traits; hence, it is suggested that the whole traditional morphometric characters in a PCA analysis and molecular data be used to discriminate the species in this genus.

Zooplankton sampling was sampling was performed by a sampling net with a spring size of 100 microns. Since 2001, there have been changes in the population composition of zooplankton species, while in 1994 and earlier Eurytemora spp. Zooplankton predominated at depths of more than 20m. Currently, in the years after 2001, more than 95% of the zooplankton population in the southern Caspian basin is Acartia tonsa. Although in this study the dynamics of the zooplankton population was different, in all seasons Copepoda was the predominant group of zooplankton. A total of 24 species of zooplankton from the groups of Copepoda, Rotifera, Protozoa, Cladocera and two species of Meroplankton from Cypris balanus and Lamellibranchiate larvae from bivalve larvae have been observed. Among the factors of entry of non-native animals, including the comb M. Leidyi, nutrient entry through the Nekarood river, different amounts of solar energy intake and consequently temperature and water currents can cause differences in zooplankton population in Goharbaran region.

Endocrine disrupting chemicals (EDCs) such as Bisphenol A (BPA) and Nonylphenol (NP) can enter the Caspian Sea by rivers from a variety of sources and they potentially pose a health risk to humans and aquatic organisms. Moreover, knowledge of their concentration is limited in the Caspian estuaries. Therefore, the present study was conducted to assess the concentration of BPA, NP and the physicochemical factors of Iranian rivers of the Caspian Sea. Water samples were collected from 49 estuaries along the coasts of Guilan, Mazandaran and Golestan provinces in August and September 2015. Obtained results were compared among estuaries and assessed with principal component analysis (PCA) and cluster analysis (CA) for clusters of NP and BPA concentration and physicochemical factors and rivers. The concentration of BPA and NP with the amount of 1.81 µg/l and 2.85 µg/l respectively was higher than standards and Talesh, Astara, Anzali, Azarood, Nashtarood, Talarood and Tajan have higher concentration of NP and BPA. The PCA revealed two components with eigenvalues >1, depicting 81.41% of the total variation of the data and also showed, EC, TDS, TSS, TS, phosphate and nitrate play important role in estuaries water quality in two major components. Outcome of CA classified similar estuaries and physicochemical parameters into 4 clusters. In conclusion, it was determined that pseudo estrogenic pollutant levels in water of the Iranian coasts of the Caspian sea have higher than those standard due to the effect of run-off from agricultural lands and industrial and municipal wastewater.

The Eurasian otter (Lutra lutra) as one of the mammals of the inland waters of Iran is at the top of the food pyramid and encounter to endanger of extinction. The diet studies are critical to understanding the ecology of wildlife and preserving their populations. The objectives of this study were the presence and diet of otter in estuary region of Acharod, Khoshkrod and Polrood rivers, in the east of Guilan province, and also the study of the level of dependency of this species on fish species of the Caspian Sea. The length of the last five kilometers of each river, as three sections with an approximate length of 1700 meters, was examined in terms of distance or proximity to the sea. The results showed that of the five km length studied of the rivers, the Eurasian Otter was present up to 4/3 km of the estuary. In total, 511 presence indices with specific seasonal changes were observed in each of the river sections. The highest index was observed in the autumn season and the lowest in the summer season. Based on the analysis and investigation of spraints, 955 prey items including fishes, crustaceans, snakes, frogs, birds and insects were observed. The highest feeding index (FI) in three studied rivers was for fish and the lowest FI was for insects. Also, the seasonal changes in food items between sections were observed. So that in the two seasons of autumn and winter in all three sections of the rivers, the highest FI was for fish. In the spring and autumn, the feeding index of the fed fish was mainly related to river fish and common river-sea fish. In summer and winter, the percentage of sea fish was higher than in spring and autumn. The feeding index of non-fish items has also increased in the summer compared to other seasons.

In this study, trends in population and species diversity of wintering waterbirds in the south Caspian Sea region, based on mid-winter censuses of waterbirds over a thirty-year period from 1988 to 2017, have been studied. The trends in population and the ecological indicators of biodiversity were respectively calculated using the RTRIM statistical package (TRends and Indices for Monitoring Data in R software) and the software SDR-IV (Species Diversity and Richness). Results showed that the average number of waterbirds in the whole Caspian region for the last thirty years was 947,853±71,073 with a range of 326.281-1.934,226 individuals. The share of Mazandaran province alone was more than the other two provinces during the study period. The total number of waterbirds recorded increased in 2004 and then formed a stable trend. Calculation of the statistical trend of changes over the 30 years in the waterbirds population size of the south Caspian region indicated a slight increase with a slope of 3.3% per year, but over the last ten years, the population has gradually declined, showing a 2.7% decrease over this latter period. The results for species diversity indices (Shannon-Wiener and Simpson D), species richness (Margalf and Minhinick), and species evenness (Pielou and Simpson E) confirmed that high values ​​of species diversity and richness and low values ​​of species evenness indices during the period of 2004-2009 were basically due to the increase in the number of species recorded and conducting more accurate censuses backed by a comprehensive census program and the participation of foreign birdwatchers. The results of this study can play a practical role in informing the ecological management of the wetlands and southern coast of the Caspian Sea.

In this study, a total of 4 Chlorophyta microalgae sampling periods were conducted at depth and depth. Chlorophyta microalgae sampling performed using Rotner breeding time, mid-breeding time and end of breeding time and one year after breeding time, from north, east, south and west of the cage. Samples were taken from fish shade (N0), 200 m from cage (N100-200) and 1000 m from cage (N1000). It is noteworthy that (N100-200) was at a distance of 100 m from the cage at the beginning of cultivation to 200m. Sampling from each station was done from three depth of surface, middle layer and depth. In total, in all four sampling periods, 11 species of Chlorophyta microalgae microalgae observed. Also, the percentage of Chlorophyta microalgae density was different and 200 meter distance from the cage had the highest percentage of 200 m distance from the cage had the highest percentage of Chlorophyta microalgae density density. It can be said that time variations such as effects on air temperature, river inflow, cage fish waste and consequently increased nutrients, water currents, and consequently salinity changes in river inflow and salinity can have significant effects. Involved in changing the population of Chlorophyta microalgae around the cage.

This study was carried out in 27 study stations in Shijan, Siakishim, Abkenar, Hendekhaleh and Rogaha(River outlets), during implementation of hydrological and hydrobiological study plans and preparing Atlas of plankton in the Anzali wetland during the years 1373(1994) from 1393(2014). Zooplankton samples were collected by P.V.C tube on every month, at each station 30 litre water sampels were filtered by 30µ zooplankton net. The samples were fixed with 4% formalin and After identification, they were photographed with Nikon photomicroscope. The results of Zooplankton study reveal that there are totally 12 Phylum that include and 217 speices in Anzali lagoon , of which 22 speices belong to phylum Rhizopoda, 4 speices belong to Phylum Actinopoda, 41 speices belong to Phylum Ciliophora , one speice belong to Phylum Porifera, 3 speices belong to Phylum Coelantrata, 2 speices belong to Annelida , 2 speices belong to Phylum Platyhelminthes, 93 speices belong to Phylum Rotatoria, 1 specie belongs to Phylum Tardigrada , 32 species belong to Phylum Arthropoda (order Cladocera) 11 Speices belong to Class Copepoda , in Class Cirripedia and Ostracoda and Diptera (Family Chironomidae) each of them consisting of one genus , 2 speices belong to Class Archnida and in phylum Mullosca Class Bivalvia, Lamellibranch larvae was identified . It is evident from the present study that Rotifera was dominant species with Brachionus calyciflorus, Brachionus angularis , Keratella cochlearis , Polyarthera vulgaris in southern Hendekhaleh and Abkenar regions and the main outlets regions.

This study was conducted to measure the concentration of five heavy metals, including lead, cadmium, mercury, arsenic, and chrome in muscle liver, and gill of the gray mullet, Liza aurata in southern part of the Caspian Sea. The samples were collected from 100 adult gray mullet in 10 stations during the sexual maturity (in the fall) and sexual rest (in the spring). The muscle, liver, and gill tissues of each fish were separated in order to measure the concentration of the heavy metals. The acid digestion method was used to extract the metals from the tissues. The concentration was determined using a graphite furnace atomic absorption spectrometer. The mean concentration of lead, cadmium, mercury, arsenic, and chrome in the muscle tissue respectively was 1.40, 0.43, 0.16, 0.07 and 0.54 µg/g during the sexual maturity and 1.90, 0.93, 0.24, 0.12 and 0.61 µg/g during the sexual rest. Generally, the uptake of heavy metals during the sexual rest (Pb>Cd>Cr>Hg>As) was higher than that during the sexual maturity (Pb>Cr>Cd>Hg>As). The concentration of the metals in the three tissues was as follows: liver > gill > muscle. The difference between tissues in terms of the concentration of the metals was significant. The comparison of the data obtained for the muscle tissue with the standards of the World Health Organization and Australian National Health and Medical Research Council showed that the concentration of all the five heavy metals (Pb, Cr, Cd, Hg, As) was higher than the global standard level, and thus, the consumption of this fish can harm people.

Coastal sediments as sensitive indicators are employed for monitoring pollution in the coastal areas. Heavy metals in surface sediments originate from natural and/or man-made sources. This study was conducted to determine natural and anthropogenic sources of some heavy metals (Zn, Cu, Cd, Pb) of surface sediment in the southern Caspian Sea during four seasons in 2013-2014. 72 surface sediment samples (with triplicate) were collected at two transects (Tinekabon and Amirabad) and tree depths (5, 10, 20 m) using Van Veen Grab sampler. The heavy metals concentrations of different extraction were measured using atomic absorption spectrometry (AAS) with flame and furnace. Results showed that maximum and minimum concentrations of copper, zinc, lead, and cadmium in the non-resistance part were 0.58-19.31, 0.83-4.21, 4.21-7.86, and 0.31-0.68 and in the resistance part were 4.70-23.33, 4.88-79.19, 7.06-14.84, and 0.23-0.46 µg/g.dw, respectively. In a conclusion, percentage of Cd in the non-resistance part was 58.58% that it contained maximum level among various heavy metals which represents a greater distribution in the anthropogenic origin. While Cu (32.14%), Zn (4.28%) and Pb (35.77%) have natural origin.

Comparative study of Heavy metals accumulation (Cd, Pb, Hg, Cu) in liver, skin and muscle tissues and Fatty acids profile of Persian sturgeon was done in West and East Southern coasts of Caspian Sea. The results showed that the metals were in accptable ranges in fish muscle (P>0.05); but metals concentration in lever was more than skin and muscle (P

Due to the short period of statistical data for other stations only the rainfall level of Bojnurd station was used to determine the coherent pattern of extreme precipitation in North Khorasan. In order to determine the patterns of rainfall, data related to sea level pressure, specificity, vertical velocity (omega), wind component (U), wind velocity component (V), geopotential height and air temperature at different levels, collected four times a day, were used. Also, Outgoing Longwave Radiation (OLR) prepared daily by the National Center for Environmental Forecast from two days before the rainfall was entered into GrADS software along with the previous parameters and analyzed using the software’s capabilities. The findings show that the prevailing atmospheric patterns during the occurrence of rainfall is the existence of a nave with a north-southwest axis in the southern part of the Caspian Sea, which causes instability, raising and transferring moist air to the studied area, causing heavy rainfall in the area. According to the vertical maps of atmospheric moisture, it was determined that the highest amount of moisture in the atmosphere was at lower levels of the troposphere. By studying the maps of the convergence nuclei of moisture at different levels, the role of the Caspian Sea in providing the moisture of such heavy rainfall is visible. The status of the atmospheric river at upper levels of the atmosphere also contributes to more severe ascent of air, increased instability, and elevated atmospheric turbulence in the region. On the other hand, falling cold air has higher latitude, which creates a frontier, increases its intensity, and stretches the frontier to the upper levels of the atmosphere.

The Caspian Sea, as the largest land-enclosed drainage area in the world has been endangered by various environmental pollutants, discharged from coastal catchment. In this study the trophodynamics of metals are investigated in different organisms from the Caspian food web. Furthermore, the species with potential bio-indicator abilities have also been distinguished. Nine species including three invertebrates Mnemiposis leidyi, Cerastoderma glucaum and Balanus improvises; five fish species Neogobius spp, Atherina boyeri, Alburnus chalcoides, Rutilus kutum and the Caspian seal Phoca caspica were studied in three regions of the southwestern Caspian: i.e. Astara, Anzali and Chaboksar. The stable isotope of primary producer (POM) was very various in each region compare to those from primary consumers. Phoca caspica had the highest average δ15N and TLs as the top of the food chain. The concentrations of metals for the most samples of fish were below the detection limits; while the concentrations were detected in most invertebrate samples. Our results suggested the abilities of Cerastoderma glucaum as indicator of Ni and Co contamination. Balanus improvises had a high capacity for Zn, Sr, Mn and Cu bioconcentration. By comparing ln-concentration of metals vs. TLs, no metal biomagnification was observed. The marine pollution index in Anzali region was higher than those in Astara and Chaboksar regions. While this study provides the basic data from southwestern Caspian Sea; C. glucaum and B. improvises could be proper bioindicator species for worldwide comparison of metal pollution.

The crustacean Gammarus sp. lives in sediment at coastal zones having an important role on food chains. It also transfers energy to higher trophic levels i.e. fishes and birds. The littoral zone of the Caspian Sea receives many pollutants from the sea and the land. Cadmium can be found naturally in low concentrations in the environment but human intervention, anthropological discharge connected to the urban and industrial activities raise the concentration of heavy metals in costal sediment and aquatic ecosystems. In the present study, Gammarus sp. was selected as a test organism because it is the abundant in southern coast of the Caspian Sea. This crustacean absorbs metals from food or water. The concentration of cadmium in the present experiment was lower than LC50. Samples were collected from the submerged mesocosm different times, i.e. 0 (control), 30, 60, 90, 150, 210 and 270 minutes. After preparing the sediment and Gammarus samples, cadmium concentration were determined using an ICP-OES. Significant differences (using ANOVA) were observed among exposure times. A t-test indicated that there was a significant difference between Gammarus and sediment in cadmium uptake. In conclusion, the present study indicated that cadmium absorption by Gammarus and sediment was a function of the exposure time and accumulation of this metal, increases over time.

To assess the sources, entry routes and degree of contamination of PAH compounds in surface sediments of the southwestern Caspian Sea coasts (Gillan province) total of 129 surface sediment samples from 28 rivers and 5 transect across the Gillan province coasts (from Astara to Lahijan; 10, 20 and 50 m depth) were collected in the spring and summer of 2012. After extraction using Soxhlet method, the samples were analysed using Gas chromatography-Mass spectrometry (GC-MS) and concentrations of 30 PAH compounds were determined. The mean of total 30 PAH compounds (TPAH30) in the coastal sediments (565.1±266.1 ng g-1) have shown significant difference (p

Suspended sediment (SS) flux in a river is an important parameter for the watershed management. The large extend of watersheds areas and limited of sediment stations measurement have been caused that different methods have been developed to SS estimation. In this study, 42 sediment measurement stations existed in south and southeast of the Caspian Sea with over 20 year period was chosen. The sediment rating curve (SRC) was drawled using discharge and SS load measurements for 42 stations, then daily SS load was estimated by using the daily discharge (Q) and the average of annual SS was computed. By using the gamma test (GT), 14 effective variables on SS was reduced to 5 main variables and the mentioned stations were recognized in four homogeneous groups by using Andrew c urves (AC). For each homogeneous group and all existed stations using five selected main variables was developed regression models for average of annual SS load. Relative error (RE), r elative bias (RBIAS) and r oot relative mean squared error (RRMSE) indices statistics are used for evaluating the accuracy of the models. The results indicated that a model was not provided for group 1. The models of g roups 2 to 4 have a good accuracy and the model of g roup 4 with RE(29%), RBIAS(12%) and RRMSE(35%) in the calibration stage, and RE(19%), RBIAS(12%) and RRMSE(25%) in the validation stage has the best performance and One model for all stations has high error. Peak discharge with two return periods (Qp) has the most impact on the average of annual SS change.

Due to the location of a domestic, industrial and agricultural zone near the Caspian Sea, this water body has long been under pressure and environmental threat. As a result of development of oil production activities in Caspian region, such as oil exploration and extraction, a large volume of oil related pollutants is released annually into this important water body. Considering the fact that hydrocarbons may cause adverse impacts on the aquatic and marginal life, the monitoring of sediment as hydrocarbons in the sea has been considered. The purpose of this article is determination of total petroleum hydrocarbon (TPH) and comparing it with other coastal area in Caspian region-in Gilan, Mazandaran and Golestan from spring 2010 to spring 2011. 225 water sample and 75 sediment sample in 15 stations during of 5 seasons have been collected and the levels of total petroleum hydrocarbon (TPH) using FT-IR were determined. Based on results level of total petroleum hydrocarbon (TPH) is the most level in autumn 2010. Also the highest and lowest level of total petroleum hydrocarbon in water were recorded in station 7 (Dastak region) and station 1 (Astara), respectively. Moreover, the highest and lowest level of total petroleum hydrocarbon in sediment were recorded in station 13 (Neka powerhouse) and station 8 (Ghasem abad), respectively. The results of ANOVA show that level of TPH in water and sediment among different seasons is significant, but there isn’t a significant difference among different stations.

In the recent years، rapid growth of the world’s population and overutilization of fresh water resources have caused fresh water shortage crisis in the world. In spite of the agricultural activities in the Northern beaches of Iran and also severe decrease of the ground water level، it still has not taken any effective measures to desalinate Caspian Sea water in large scale. In this research، desalination of Caspian Sea water by Silica Nano-Particles with the diameter less than 50 nano meters for agricultural usage has been studied. In this study، by primary experiments the concentrations of the studied parameters including Electrical Conductivity (EC)، Sodium (Na)، Potassium (K)، Calcium (Ca)، Magnesium (Mg) and Turbidity of the sea water raw sample were measured. By useing of Jar Test، various dosages of Silica Nano- Particles and the wide ranges of pH were examined. The results show that the 0. 45 gr/lit of Silica Nano-Particles is the optimum dosage and pH=10 is the optimum pH for desalinating of Caspian Sea water. Meanwhile، the results revealed the extraordinary effect of Silica Nano-Particles on the studied parameters and has reduced their concentrations significantly so that the concentrations of Na، K which are the most important factors for water salinity، reached to zero.