Correlation between changes of Chlorophyll-a and transparency in the Southern Caspian Sea

Chlorophyll-a is a main pigment for photosynthetic process in marine phytoplankton and by it either amount of biomass can be estimated or can be considered as an index for trophic level of aquatic ecosystem. In year 1996, 81 secchi disc depth were measured and 1601 samples of chlorophyll-a were collected seasonaly from the southern Caspian Sea. The results showed that average chlorophyll-a in seasonals of spring, summer, autumn and winter were 1.072, 0.550, 1.848, 0.966 mg/m3 and depth of transparency were 6.42, 8.86, 5.62 and 5.22m, respectively. The statistical analysis showed a significant correlation (P<0.01) between these two parameters in the southern Caspian Sea. More studies are needed to find out higher precise correlation

Phosphorus forms of the surface sediment in the Iranian coast of the southern Caspian Sea

Sediments from the southern Caspian Sea, located in Iranian coast were examined on the basis of P-fractionation (five forms of phosphorus) by a sequential extraction scheme. Ninety-six surface sediment samples (for each season with triplicate) were collected from eight sampling transects in 10 and 100 m depths during summer and winter in 2010-2011. The result indicated that the most abundant forms of phosphorus were calcium bound phosphorus. Relative abundance of other forms of phosphorus follow the order: organic-P>Fe-P>Al-P>Absorbed-P. The loosely absorbed phosphorus represented <1% of the sedimentary inorganic phosphorus, while the Fe/Al phosphorus ranged 5–6%.The calcium bound phosphorus showed considerable contribution (88%) to the sedimentary inorganic P-loads

Quantification of individual phosphorus forms in surface sediments of the Southern Caspian Sea - Iranian Coast: A sequential extraction procedure

Seventy-two sediments from four stations (Anzali, Tonekabon, Noshahr and Amirabad), located in Caspian Sea-Iranian coast were examined on the basis of P-fractionation in autumn and winter of 2013-2014. Several forms of the phosphorus in sediment were separated and extracted according to sequential extraction method. Then the extracted phosphorus in each fraction was determined by UV–Vis spectrophotometry. In addition, total concentrations of Ca, Fe and Al in sediment fractions were also measured by atomic absorption spectroscopy. In autumn the rank order of P-fractions was: Ca-P>Residual-P>BD-P>Al-P>loosely-P and in winter it was: Ca-P>BD-P>Residual-P>Al-P>loosely adsorbed-P. In both season the loosely adsorbed phosphorus (NH4Cl–P) represented < 1% of the sedimentary inorganic phosphorus, while the reductant phosphorus (BD–P) ranged from 2.7 to 4%. The calcium bound phosphorus (Ca-P or HCl–P) showed considerable contribution (89-91%) to the sedimentary inorganic P-loads. The metal oxide bound phosphorus (Al-P or NaOH–P) was 1.2-1.5% and Residual-P was 2.3-4.5%. Concentration of BD-P increased with increasing depth in all stations and the concentration of other fractions increased in most stations. Sampling seasons had significant effect on variance of most P-fractions and other sediment features. TP and BD-P were positively correlated with Fe_tot (p<0.05)

Assessment of resistance and non-resistance fractions of heavy metals concentration (Fe, Mn, Cr, Ni) in surface sediments from the southern of Caspian Sea of two stations (Tonekabon and Amirabad)

This study was conducted to determine some heavy metals (Fe, Mg, Cr, Ni) of surface sediment in the southern Caspian Sea during two seasons (Summer and Winter) in 2014-2015. 36 surface sediments samples (with triplicate) were collected at two stations (Tonekabon and Bandar Amirabad). All samples were analyzed using sequential extraction to indicate natural and anthropogenic sources. The results indicated that the percentage of non-resistance fraction in Tonekabon area were measured 3.5,45.0, 22.1 and 6.0 for Fe, Mg, Cr, Ni, respectively and in Amirabad area were 23.0,2.6,1.8 and 4.0, respectively. On the other hand, the percentage of resistance fraction values were obtained 96.5, 55.0, 77.9 and 94.0 in Tonekabon, and 77.0, 97.4, 98.2, and 96.0 in Amirabad region. The chemical speciation of Fe, Mg, Cr, Ni in most sampling stations were in the order of residual> oxidisableorganic > acid-reducible >exchangeable. The order of total concentration, non-resistance and resistance fraction were observed Fe>Mn>Ni>Cr, Mn>Fe>Ni>Cr and Fe>Mn>Ni>Cr, respectively. As a conclusion, results of total concentration, resistnace and non-resistance of Fe, Mn, Ni and Cr were lower than standard and earth shell (Igeo) in this area. This is shown that surface sediments of this area were not polluted with these heavy metals and bio available fraction provides little indication of potential interactions with the biotic components present in this environment

Reproduction, sexual maturity and fecundity of anchovy kilka (Clupeonella engrauliformis Svetovidov 1941) in Iranian waters of the Caspian Sea

Reproduction period, spawning peak and sexual maturity in anchovy kilka were investigated during the year 2006 for sustainable yield assessment in Iranian waters of the Caspian Sea. The mean fork length, total weight and age were 118±5.9mm, 11±1.7g and 4.6±1.2 year, respectively. Mean (±SD) absolute fecundity was 12625±5533 ovules. More than 50 percent of the fish specimens matured when their length exceeded 92.5mm. The results showed that reproduction of anchovy kilka occurred in autumn, and spawning occurred throughout the year and especially in winter. The length and age ranges were found to be shortened compared to the past years with many older fish and less younger ones (< 2 years) in the catch which sharply decreased recruitment. This phenomenon is thought to be due to overfishing synchronized with invasion of M. leidyi pushing kilka to spawn in winter, which all cause collapse of anchovy kilka stocks in the Caspian Sea. We postulate that anchovy kilka has adopted the strategy of spawning year round to mitigate the negative effects of overfishing and invasion of M. leidyi

Scale characteristics of the bloom event: A case study in the Iranian coastal waters of the Southern Caspian Sea

Nutrient enrichment in water and sediments due to excessive anthropogenic activities in recent years has caused excessive algal growth in the Caspian Sea. The current study was conducted to determine the abundance of phytoplankton community, the dominant species and chlorophyll-a [Chl-a] concentration during algal blooms in the Iranian coastal waters of Caspian Sea through four seasons from 2013 to 2014. The minimum and maximum phytoplankton abundance recorded were 73±31 and 505±55 million cells m-3 in summer and winter, respectively. The median concentration of Chl-a increased to 5.81 mg m -3 in autumn, as compared to the annual median value (2.43 mg m^-3 ). The results indicated that the bloom started in autumn and it continued falling with a low concentration during winter (Chl-a: 2.59 mg m^-3). The three species Stephanodiscus socialis, Binuclearia lauterbornii and Thalassionema nitzschioides were classified in medium bloom class (100-1000 million cells m^-3) in spring, summer and autumn, respectively. While in winter Pseudonitzschia seriata (harmful species) and Dactyliosolen fragilissima were classified in medium bloom class with high relative frequency. The scaling of bloom abundance revealed that bloom initiation coincided with 10 million cells m^-3 of the dominant phytoplankton species. The bloom at the regions with more than 100 million cells m^-3 of total phytoplankton abundance and dominant species was overlapped with the bloom regions based on Chl-a concentration

Population dynamic of bony fishes in the southern part of the Caspian Sea

This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment and Acceptable Biological Catch (ABC) of bony fishes in the Iranian coastal waters of Caspian Sea in the years 2010-2011 and 2011-2012. According to the result, the numbers of beach seines were 131 and 128 and their fishing efforts were observed 50184 and 42255 beach seining during 2010-11 and 2011-12, respectively. The catch per unit of effort CPUE) was calculated 182.9 and 205.6 kg/haul during two sampling periods, respectively. The total catches (including illegal fishing) were also obtained 16601.5 mt and 17034.1 mt during 2010-11 and 2011-12, respectively. The highest proportion of catch was belonged to kutum and golden grey mullet (86% and 88%, respectively) in two fishing seasons aforementioned above. Growth parameters of kutum were estimated as K=0.21/yr, L_∞ = 60.0 cm, t-0 = 0/yr. The Growth parameters were K=0.18/yr, L_∞ = 61.1 cm, t-0 = -0.14/yr for golden gray mullet and were K=0.12/yr, L_∞ = 73.6 cm, t-0 = 0.92/yr for common carp. Based on catch-at-age data, in the years 2010-2011 and 2011-2012, the total biomass, from the biomass-based cohort analysis were estimated 41700mt and 34400 mt for kutum and 14600 mt and 14400 mt for golden grey mullet, respectively. The reference points of F0.1 and F35% were 0.41/yr and 0.34/yr for kutum and 0.36/yr and 0.33/yr for golden grey mullet, respectively. Stock enhancement plays an important role in recovery of kutum stocks in the Iranian coastal waters of Caspian Sea. There is a significantly negative correlation between fingerlings released and condition factor (CF) and recruitment and CF. The different trends for fingerlings, recruitments and CF suggest that CF may be partly density-dependent, declining at high population sizes due to intra-specific competition. Therefore, more research should be conducted to determine the desirable level of artificial propagation. Food consumed by fish species, Rutilus frisii kutum, Rutilus rutilus caspicus, Cyprinus carpio, Liza auratus and Liza saliens were included Foraminifera, Porifera, Annelida, Mollusca, Arthropoda, filamentous algae, fish eggs and detritus.The results showed that Rutilusfrisii kutum generally feed on Balanus and Cerastorderma. The main food item for Cyprinuscarpio, Liza auratus and Liza salienswas detritus. Based on available models, the ABCs were estimated as 6600-7400 mt for kutum and 2200-2800 mt for golden grey mullet (with precautionary approach 6600 mt and 2200 mt for kutum and mullet, respectively) in 2011-12. Two species (kutum and golden grey mullet) are vulnerable to environmental factors, and these factors should be considered in the stock assessment and management of the fish. For two species, the ABC with a lower andmore accurate value based onmore information, should be selectedfor the implementation of a precautionary management approach

Features of phytoplankton community in the southern Caspian Sea, a decade after the invasion of Mnemiopsis leidyi

Phytoplankton study has become more significant in the Caspian Sea due to the occurrence of ecological events such as algal blooms and the introduction of the invader species(Ctenophore, Mnemiopsis leidyi). A seasonal study was conducted to investigate the features of phytoplankton community one decade after this invasion in the Iranian coast of Caspian Sea during 2009-2010. According to the results, 195 species in eight phyla of phytoplanktons were identified. In spring, Bacillariophyta and Pyrrophyta were the dominant phyla with 40 and 29% of total abundance, respectively. In summer and winter the dominant phyla were made by Cyanophyta (92%) and Bacillariophyta (94%), respectively. The Bacillariophyta (57%) and Cyanophyta (28%) were the first and second dominant phyla in autumn . It seems that the ctenophore invasion into the Caspian Sea (due to the changes in nutrient levels and decline of phytoplankton grazers) and human's destructive activities play an effective role on phytoplankton community during the period. These changes were mainly accompanied with appearance of new and harmful species (with the ability of severe bloom making) and consequently, displacement of native species in this semi-enclosed ecosystem

Investigation and determination of some heavy metals in the Aras river fish species in the East Azerbaijan Province (2015-16)

This study was conducted to determine heavy metals (Cu, Mo, As, Hg) in fish species of Aras River (East Azerbaijan) at four stations (From Julfa to 25km after Nourdos border) during four seasons from 2015 to 2016. Thirty eight specimens of fish were collected by using of electrofishing as the main method for sampling. The amounts of heavy metals were measured by using an atomic spectrophotometer in the muscle tissue of specimens. Bioaccumulation factor was also calculated for each species. The amount of bioaccumulation factor for molybdenum was the highest and the arsenic had the lowest amount. The highest concentration of copper was in Barbus lacerta with a mean of 13.6 ± 11.3μg /g dry weight and for the molybdenum, Alburnoides bipunctatus had the highest mean concentration (11.7±4.9) μg / g dry weight. The average concentration of mercury (13.1 ± 1.5 μg / kg dry weight) was highest in Alburnus alburnus. Regarding the arsenic elements, as it was analyzed in a small number of specimens, the highest concentrations were recorded in Alburnoides bipunctatus. According to ANOVA, there were a significant difference between mean concentration of copper in different species (p<0.05) and the Duncan test has distinguished Alburnus alburnus from other species

Study of indicator bacteria and ovary of nematode at the surface water, underwater and sewage in the basin of Mangol dam (Mazandaran province)

Indicator of bacteria such total coliforms and fecal coliforms are one of the most important environmental factors that effect on water quality. Haraz river is one of three rivers in north of country and it originate from central Alborz. Overall, discharge of unborn sewage, agriculture pesticides, seasonal raining was caused decreasing of quality of the river. Therefore, quality and quantity of the grandwater, surface water and sewage in different zone of this river such Mangol dam is necessary. In this study, total coliforms and fecal coliforms and nematode ovary in 13 stations of Haraz including Sorkhrood, Klodeh, Amol Esar Town, Helomsar, Mangol dam, Karesang, Jalav bridge, Norroud, Tehran 115, Larijan, Abeask, Lasem, Lar (pleur) were surveyed. ECC Chrome agar was used for counting and isolation of coliforms groups and nematode ovary counting was done as formal – ether sedimentation method. The results showed that maximum and minimum of total coliforms in surface water was observed in Sorkhrood (9.4 CFU/100ml) and Lasem (4.2CFU/100ml) and also maximum and minimum of fecal coliforms in Sorkhrood (3/2 CFU / ml) and Lasem (1/1CFU/100ml) respectively. Maximum and minimum of these bacteria in ground water were Abeask (4 CFU /100ml) and Helomsar (9/1 CFU/100ml) (for total coliforms) and Abeask (7/1 CFU/100ml) and Helomsar, Klodeh and Larijan (2/1 CFU/100ml) (for fecal coliforms) respectively. Maximum and minimum of total and fecal coliforms in sewage were Norroud (1/3 CFU/100ml) and Amole Esar Town (2/2 CFU/100ml) (for total coliforms) and Norroud (6/1 CFU/100ml) and Amole Esar Town and Tehran 115 (2/1 CFU/100ml) (for fecal coliforms) respectively. Ovary of Nematode in sewage was 30 and 124 in Norroud and Amole Esar Town respectively. The conclusion of this study was showed that quality of Haraz is low level and not proper for drinking and swimming