Hydrological and hydrobiological study in the Syiah-rud River

The study was conducted in Syiah-rud River. The fishes were belonged to five families: Cyprinidae, Atherinidae, Gobiidae, Mugilidae and Cobitidae. The aquatic plants was composed of three groups: marginal, submerged and floating. Among the submerged aquatic plants, potamogetons was the most dominant family and had a large distribution in station IV. 37 genera were also identified from four Algae phylum. There were twelve families in benthos population, which had more abundance in station II. In study of water quality, 15 physical and chemical factors were measured. The highest amount of phosphat was 3.12 mg/1 which was seen in stations III and IV. Also the highest amount of NH4+ and N were seen in station III, probably due to existing sewage factories in this region

Monitoring and rearing survey of Mnemiopsis leidyi in the southern of Caspian Sea

With the arrival of the invasive comb jelly Mnemiopsis leidyi in the Caspian Sea in 1991, extensive changes have been occurred. Therefore, this project aims to investigate the comb jelly M. leidyi monitoring and rearing in the southern Caspian Sea in 2013. To survey of M. leidyi and zooplankton abundance and biomass, sampling was carried out during the four seasons at spring, summer, autumn and winter in 4 half-transect (Anzali, Tonekabon, Noshar and Amirabad) and also samples for the ctenophore rearing was done at depths of 5, 10 and 20m. Sampling was performed with a 500 and 100 μ plankton net vertically at layers of 0-5, 0-10 and 0-20 m. 12 aquaria of 50 L volume were designed with salinity of the Caspian Sea to study the breeding and fecundity with aeration. 3 of aquariums with salinity of 9±1pp, 3 with 11±1ppt and 3 of 12±1 ppt filled with Caspian Sea water. Water temperature in each of the three treatments was set in 20±2oC, 23±2^oC and 25±2^oC. 3 of aquaria were set at the salinity of 12.5 ppt and at the same temperature of the Caspian Sea (20, 23, 25^oC) as control. Mean annually Mnemiopsis abundance and biomass were 16.8±1.5 ind.m^3 (139.5±41.1 ind.m^2) and 1.9±0.1 g.m^3. (5.3±0.7 g.m^2). Maximum mean abundance was recorded in autumn with 36.6.7±13.8 ind.m^3 (355.1±103.6 ind.m^2) and maximum biomass was observed in summer of 1.9±0.2 g.m^3(15.0±1.5 g.m^2). Minimum mean abundance was found in spring with 1.3±0.5 ind.m^3 and minimum biomass was in winter of 0.01±0.005 g.m^3. Regional distribution of M. leidyi in the southern Caspian Sea showed aggressive area in terms of density and biomass are areas with significant differences (P<0.05). Comb jelly population showed that both West and East in terms of abundance and biomass were similar but different with the central region. Eastern and western regions compared to the central region have the higher abundance. Laboratory studies on M. leidyi reproduction of different sizes at different temperatures showed an average of 12 eggs per day spawning. Maximum spawning rate was registered with 115 eggs per day, for M. leidyi of 46-15 mm (0/7-9/7 g) which increased with increasing size. Average M. leidyi spawning recorded in 11ppt with 25oC was twice in 12ppt (14 eggs. Day^-1 ) while in salinity of 12ppt of 23^oC the fecundity was two half-times in temperature of 25oC and equal of 20oC. Maximum M. leidyi fecundity was recorded at 23^oC with salinity of 12±1ppt with 22.8±35.5 eggs.day^-1. There was a direct regression between size and weight fecundity of M. leidyi, in which fecundity of more than 16 mm length showed the maximum spawning. Based on the study looks at the rise and persistence parameters of comb jelly, it seems two main factors such as water temperature to the desired value, especially in summer (22-30°C), and food availability (zooplankton) have more roles in the increasing of M. leidyi the southern of the Caspian Sea. After the invasion of M. leidyi into the Caspian Sea, not only the abundance and biomass of zooplankton decreased but also the species diversity decreased from 36 to 15 species. Hence, it seems the decline in the South Caspian comb jelly was due to decreased of fecundity for lack of zooplankton feeding resources

Hydrology and hydrobiology of Chaloos River

The Chaloos River originates from Alborz Mountain and enters into the Caspian Sea in Chaloos city. Five stations were chosen in different areas for the study during 1371 to 1372 (1992-93). Total variation range of hardness decreased 1 to 5 station, but measure NH4 and NO3 increased. 45 genera belongs to 4 phyla of phytoplankton as follows: Chrysophyta, Chlorophyta, Euglenophyta and Cyanophyta. Zooplankton existing in this river belong to animal classes, which had more abundance in Sarcodina and Monogononta. The benthos river establish Insecta larvae of Ephemeroptera, Coleoptera, Diptera, Plecoptera and Odonata (Orders). Chaloos fishes included to 4 families, 10 genera and 12 species. Cyprinidac consisted 66.7% of total fish and had maximum diversity at the various stations

The survey of feeding and reproduction of cetenophora Mnemiopsis leidyi in the southern of Caspian Sea

Menmiopsis leidyi was entered into Caspian Sea from Black Sea and mass population constitutes in the southern Caspian Sea. In this surveys, the relationship between length and wet weight measured and length and weight followed by this equation: n=384, R^2=0.87 w=0.003L^9005 . The relationship of dry and wet weight calculated, in this surveys, the ratio of dry weight to wet weight was equal to 1.615% in 12 salinity. In vitro, the clearance rate at 12 and 27 C were 52.48 and 107.33 ml/h, respectively, daily ration at above temperatures were 1.98 and 16.65 respectively. Mnemiopsis leidyi can feed Acartia in accordance to 16.5 mg/1gbw (body weight) at 27 C in one day. The average digestive time in 12 C and 27 C were 77.50 min and 36 min respectively. The digestive value in 27 C was 2.5 fold than 12 C. The result indicated that clearance rate, daily ration and digest were increased in high temperature. Stomach content of Mnemiopsis leidyi was shown that this organism utilized from Acartia and Balanus, in addition, stomach content of kilka including two species of zooplankton from the southern Caspian Sea. Stomach contents of clupeonella cultiventris contain more than 54 percent of Acartia and its nauplii. This frequency observed in cluponella engrauliformis and clupeonella grimmi. On basis of zooplankton sampling in the sea, over 90 percentage of zooplankton populations contain Acartia

Hydrology, hydrobiology and environmental pollution in the southern Caspian Sea

The project investigates the relationship between the biological parameters (phytoplankton, zooplankton, Macrobenthic and ctenophore- Mnemiopsis leidyi) and environmental parameters, nutrients and environmental pollutants (oil, pesticides, heavy metals, and detergents) in water and sediment, at the southern Caspian Sea in 2010-2011. Sampling was carried out in four seasons (spring, summer, autumn and winter) and in eight transects perpendicular to the coast (Astara, Anzali, Sefidroud, Tonekabon, Noshahr, Babolsar, Amir Abad and Bandar Turkmen). Samples were collected from the different layers at depths of 5, 10, 20, 50 and 100 meters. The relationship between biological and environmental parameters surveyed through parametric and multivariate statistical methods. Result showed that the annual mean of environmental parameters and nutrients concentration such as water temperature, pH, transparency, DO, ammonium, nitrate, inorganic nitrogen (DIN), organic nitrogen (DON), inorganic phosphorus (DIP), organic phosphorus (DOP) and soluble silicon (DSi) at euphotic layer were 16.70±0.43 (ºC), 8.38±0.01 (m), 5.48±0.05 (ml/l), 1.52±0.06 (µM), 1.80±0.08 (µM), 3.41±0.10 (µM), 43.3±0.9 (µM), 0.32±0.01 (µM), 0.52±0.02 (µM), 8.88±0.22 (µM), respectively. Meanwhile, annual mean of environmental pollutant such as PAHs and OCPs in sediment were recorded 0.88±0.16 (µg/g.dw) and 9.78±2.20 (µg/g.dw), respectively. In addition, annual mean of heavy metals such as Zn, Cu, Ni, Pb and Hg in sediment were obtained 247±46 (µg/g.dw), 29.5±1.5 (µg/g.dw), 49.9±4.9 (µg/g.dw) and 0.179±0.800 (µg/g.dw), respectively. Annual mean abundance of biological parameters namely phytoplankton, zooplankton and M. leidyi (0-20m) at photic layer were 238±17 (million cells/m^3), 4808±362 (individuals/m^3) and 26±3 (individuals /m^3) respectively, and for biomass were 747±60 (mg/m3), 44.3±5.0 (mg/m^3), 2.15±0.31 (g/m^3). Annual mean abundance of those biological parameters at below of photic layer (50-100m) were 104±35 (million cells/m^3), 843±92 (individuals/m^3) and 2±1 (individuals /m^3) respectively, and for biomass were 412±93 (mg/m3), 9.1±1.0 (mg/m^3), 0.15±0.05 (g/m^3). Annual mean abundance and biomass of macrobenthic were 5073±1225 (individuals /m^2) and 144±73 (g/m^2), respectively. Annual mean annual percentage of TOM, Gravel, Sand and Silt-clay were recorded 3.74±0.26, 0.92±0.32 , 22.51±4.97 and 76.67±5.01, respectively. The stratification of water column was strongly based on gradient of water temperature and the phenomenon (difference of temperature between water layers) was more clear in this study compared to previous years. Temperature and biological factors (phytoplankton) were effected on changes of dissolved oxygen at warm and cold seasons summer and winter), but coefficient factor of temperature was higher than biological factors in winter. The nutrients concentration (with the exception of inorganic phosphorus) in different years 2008-2009, 2009-2010 and 2010-2011 increased compared to 1995-1996 (the year of stability of ecosystem). One of the reason attribute to the presence of the ctenophore (M. leidyi) in Caspian Sea after 1999. The annual correlation of phytoplankton abundance and temperature was reversed but seasonal pattern was varied at each season (within a year). In this study, the Caspian Sea contained the conditions of nitrogen limitation (55%) and nitrogenphosphorus limitation (6-43%) as well as phosphate limitation (2-39%) (DIN/DIP>20) . Inspite of no silica limitation (sufficient concentration of silica) in the Caspian ecosystem, Bacillariophyta was not dominance phylum at whole seasons.It seems that other factors such as the temperature changes of seasons, the effects of predation and feeding of the next chains of the food chain, the difference of the ability in the growth and reproduction, competition (uptake of nutrients) in dfferent groups of phytoplankton and stoichiometry of the nutrients (nitrogen and phosphorus) were caused of non-diatoms dominance at most seasons. As, Pyrrophyta and Bacillariophyta were dominant at spring and winter, respectively and Cyanophyta was pre-dominant at summer and autumn. Multivariate analysis showed the significant correlation between Coppepoda and oxygen and water temperature only. The other gropus of zooplankton did not show any significant correlation with environmental parameters. It might be due to stronger effects of other parameters such as food and predators on different groups of zooplankton at each season and abundance of zooplankton groups indirectly affected by environmental parameters. In this study, Shannon diversity indices of zooplankton and phytoplankton were closer to 1995-96 values and showed diferent trend compared to 2009-2010. However it is not enough reason for recovery of ecosystem in to the stability of Caspian Sea. It is because of other negative evidiance such as strong increasing trend of phytoplankton to zooplankton biomass ratio in all seasons and regions particularly the 2009-2010 and 2010-2011 years compared to 1995-96 (the year of stable ecosystem). In the other word, the balance between the biomass of the first and second of the food chain has been disturbed and the value was much much higher than the year of stable ecosystem in 1995-96. Based on multivariate analyses, there was not significant correlation between zooplankton groups and some edible phytoplankton species, vise versa zooplankton groups consumed some unsuitable species of phytoplankton (based on size, nutritional value, difficulty of digestion and absorption, the potential of toxicity and harmfulness). The lack of expected relationship and routine rules of nutritional between zooplankton and phytoplankton are the more resons of instability in the ecosystem. In current study, dominant group of macrobenthos (polychaeta) observed in depths less than 20 meters which the percentage of silt-clay and sand were 74 and 26, respectively. It seems that this ratio of silt-caly and sand was suitable for their living and accumulation. PCA analysis showed that increasing the percentage of TOM and siltclay accompanied to the decreasing of macrobenthos abundance while increasing the temperature, dissolved oxygen and pH had a positive effect on macrobenthos abundance in most seasons. Increasing the abundance of macrobenthos at all seasons (except spring) would not be a strong indication of improvement of Caspian ecosystem after the ctenophore introduction stress and unfavorable evidence such as low Shannon diversity index observe in the results. Meanwhile, in the present study, Streblospio and oligochaeta (invasive growth and advantage to the food uptake and habitat and sediment seeding) similar to the years of 2008-2009, 2009-2010 still were dominant groups insteade of Gammaridae family (feeding on suspended solids). This means that sediment has a noteworthy amount of organic matter which indicate to the trophic level of ecosystem tend to eutrophy level. The comparison of results on this study to previous studies on biological parameters (phytoplankton, zooplankton and macrobenthos) indicating to the persistence of stress (such as biological and anthropogenic) on their changing population patterns (quantitative relationships between species) and structural patterns (species composition and seasonal succession of dominant species). In other words, many species (both macroscopic and microscopic) of the Caspian Sea are still vulnerable to complications of stressor factors. In order to protection and sustainable exploitation of this worth ecosystem it is necessary to look more serious studies and practical techniques from the relevant organizations in this area

Hydrology and Hydrobiology of Chaloos River

The Chaloos river originates from Alborz mountain and enters into the Caspian Sea in ChaJoos city. Five stations were chosen in different areas for the study during 1371 to 1372 (1992-93). Total v'ariation range of hardness dccrcased 1 to 5 station, but measure NH4 and NO3 increased. 45 genera belongs to 4 phyla of phytoplankton as follows: Chrysophyta, Chlorophyta, Euglenophyta and Cyanophyta. Zooplankton existing in this river belong to animal classes, which had morc abundance in Sarcodina and Monogononta. The Benthos river establish Insecta larvae of Ephemeroptera, Coleoptera, Diptera, Plecoptera and Odonata (Orders). Chaloos fishes included to 4 families, 10 genera and 12 species. Cyprinidac consisted 66.7% of total fish and had maximum diversity at the various station