Accelerating Effects of Cyclic Creep Due to the Alternative Load Compared with Constant Load for CD 304L

На основании результатов испытаний на одноосное растяжение выполнена сравнительная оценка ускоренных эффектов циклической ползучести в условиях переменного и постоянного нагружений для аустенитной нержавеющей стали 304L, широко используемой в энергетике и нефтехимической промышленности из-за ее повышенных характеристик сопротивления высокотемпературной ползучести и усталости. Образцы для испытаний получены из холоднотянутых прутков, материал соответствует спецификации ASTM A276-05A. Испытания проводились при температурах 687, 717 и 737°С в условиях знакопеременного и постоянного нагружений. Изучены эффекты переменной нагрузки и времени выдержки нагрузки на механическое поведение материала и характеристики усталости и ползучести.На основі результатів випробувань на одноосьовий розтяг виконано порівняльну оцінку прискорених ефектів циклічної повзучості в умовах змінного і постійного нагружений для аустенітної нержавіючої сталі 304L, широко використовуваної в енергетиці та нафтохімічної промисловості через її підвищених характеристик опору високотемпературної повзучості і втоми. Зразки для випробувань отримано з холоднотягнутих прутків, матеріал відповідає специфікації ASTM A276-05A. Випробування проводилися при температурах 687, 717 і 737°С в умовах змінного й постійного навантажень. Вивчено ефекти змінного навантаження та часу витримки на механічну поведінку матеріалу і характеристики втоми й повзучості

Reversible energy absorption of elasto-plastic auxetic, hexagonal, and AuxHex structures fabricated by FDM 4D printing

The present study aims at introducing reconfigurable mechanical metamaterials by utilising four-dimensional (4D) printing process for recoverable energy dissipation and absorption applications with shape memory effects. The architected mechanical metamaterials are designed as a repeating arrangement of re-entrant auxetic, hexagonal, and AuxHex unit-cells and manufactured using 3D printing fused deposition modelling process. The AuxHex cellular structure is composed of auxetic re-entrant and hexagonal components. Architected cellular metamaterials are developed based on a comprehension of the elasto-plastic features of shape memory polylactic acid materials and cold programming deduced from theory and experiments. Computational models based on ABAQUS/Standard are used to simulate the mechanical properties of the 4D-printed mechanical metamaterials under quasi-static uniaxial compression loading, and the results are validated by experimental data. Research trials show that metamaterial with re-entrant auxetic unit-cells has better energy absorption capability compared to the other structures studied in this paper, mainly because of the unique deformation mechanisms of unit-cells. It is shown that mechanical metamaterials with elasto-plastic behaviors exhibit mechanical hysteresis and energy dissipation when undergoing a loading-unloading cycle. It is experimentally revealed that the residual plastic strain and dissipation processes induced by cold programming are completely reversible through simple heating. The results and concepts presented in this work can potentially be useful towards 4D printing reconfigurable cellular structures for reversible energy absorption and dissipation engineering applications

The survey of diversity, distribution and abundance of phytoplankton in the southern of Caspian Sea

The survey sampled during the fourth stage of the season was in 1387. Sampling in eight directions perpendicular (transect) to the beach and 480 samples was performed. In each transect from Astara to the Turkmen 5 stations at depths of 5, 10, 20, 50 and 100 m were selected for sampling. The total number of 191 species was identified; Bacillariophyta category species number was 97, equivalent to %50.8, category of Chlorophyta 28 species, equivalent to %14.7, category of Pyrrophyta 26 species, equivalent to 13.6 %, category of Cyanophyta 25 species, equivalent to 13.1% and category of Euglenophyta 15 species, equivalent to 7.9% of all species formed. Average abundance of phytoplankton was 27947500(SD=2465184) n/m^3. The average biomass was 125.51(SD=8.84) mg/m^3. Abundance and biomass in spring and summer, autumn and winter have been significant differences (p <0.05). The highest frequency was in winter, autumn, summer respectively and spring was (p <0.05) and the highest biomass in winter, fall, spring and summer was respectively (p <0.05). Bacillariophyta category has the highest abundance equal to 14390833 ± 16262.35 n/m^3 (mean ± standard error) were equivalent to %51.49 of the total abundance, Euglenophyta category has the least density equal to 109791 ± 16262.14 n/m^3 (mean ± standard error), which is equivalent to % 0.39 of total abundance were included. Also Pyrrophyta category has the highest biomass equal to 69.66 ± 5.53 mg/m^3 (standard error ± mean) were equivalent to %53.14 of the total biomass and Chlorophyta category with an average of 0.68 ± 0.11 mg/m^3 (mean ± standard error) have the lowest biomass, were equivalent to %0.54 of the total. Phytoplankton Categories in every season, with biomass and abundance have been different (p <0.05). Abundance and phytoplankton biomass in the upper layer and lower layer varies with depth of 50 meters (p <0.05). With distance from shore and depth increases, reducing the mean abundance and biomass were observed (p <0.05). The highest and lowest abundance of phytoplankton was observed at depths of 10 and 100 meters respectively. The maximum amount of phytoplankton biomass in surface areas of deep stations 20 m and the lowest biomass sampled at the deepest point of the station was 100 meters. Abundance and biomass of phytoplankton in the deep layers of the sample with significant difference (p<0.05). So that the highest abundance layers of 10 m, the surface layer of 5 m, 20 m, 50 m and 100 m, respectively(p <0.05), and the most biomass in the surface layers of 5 m, 20 m, 10 m, 50 and 100 meters, respectively (p <0.05). Abundance and biomass of phytoplankton in transects was significant difference (p <0.05). Most phytoplankton respectively transect Astara, Babolsar, Anzali Amirabad, Turkmen, Sefidrud, Noshahr, Branch was observed (p <0.05) and in terms of biomass, respectively transects Astara, Anzali, Sefidrud, Babolsar, Noushahr, Branch, Amirabad and Turkmen values were higher (p <0.05). Species diversity indexe (Shannon – Wiener) phytoplankton was equivalent to 2.92. Environmental conditions and nutrients in different seasons on these parameters influenced the way that species diversity was lowest in summer and in autumn, winter, and spring, respectively, species diversity increased

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

The survey of diversity, distribution and abundance of phytoplankton in the southern part of the Caspian Sea

The Study of phytoplankton in the Caspian Sea was substantially started in the 1990s with the aim to produce and record data. phytoplankton study in this area became more important because of the occurance of some ecological events in recent years (such as bloom and arrival invader species). The study was seasonally conducted in western (Giulan province) to eastern coast (Golestan province) at 8 transects (Astra, Anzali, Sefidrud, Tonekabon, Nowshahr, Babolsar, Amirabad and Bandar Turkman) from inshore (5 m depth) to offshore (100 m). 476 samples were collected to study quantification and qualification of phytoplankton in 2009-2010. Results showed that 195 species of phytoplankton were identified in 8 phylums which were classified to Bacillariophyta (81 species), Pyrrophyta (33 species), Cyanophyta (28 species), Chlorophyta (38 species), Euglenophyt (11 species), Xantophyta (1 species), Chrysophyta (2 species) and Haptophyta (1 species). Abundance and biomass of phytoplankton were significantly different between euphotic layer (0 to 20m depths) and aphotic layer (50 to 100m depths) (p0.05). In spring, Bacillariophyta and Pyrrophyta with 40% and 29% of total abundance were dominant phylum at euphotic layer. In fall, Bacillariophyta (57% of total abundance) and Cyanophyta (28% of total abundance) were the first and second dominant phyla. While in summer and winter the predominant phyla was made by Cyanophyta (92% of total abundance) and Bacillariophyta (94% of total abundance) respectively. Species richness in western, central and eastern regions was 119, 141 and 147 respectively. Shannon index was 2.39 and 2.04 at euphotic layer and below photic layer, respectively. Shannon and evenness indices in eastern region was lower than western and central regions. Meanwhile, Shannon index in spring and autmn (2.50 and 2.39) was higher than summer and winter (0.21 and 0.36). In photic layer, dominant species were Stephanodiscus hantzschii Chrysochromulina sp. and Exuviaella cordata in spring. While Oscillatoria sp. was the predominant species in summer. In fall, dominant species contained Thalassionema nitzschioides and Oscillatoria sp. Finally, Pseudonitzschia seriata and Cerataulina pelagica made the most abundance species in winter. The dominant species in the below phoyic layer was very similar to photic layer. The mean abundance of Pseudonitzschia seriata , Oscillatoria sp. and Dactyliosolen fragilissima was higher than other species in all regions of study area (west, middle and east). Seasonal succession of dominant species were under the influence of natural factors such as sunlight, heat, river currents, wind and vertical mixing of water. However it seems that the invasion of ctenophore into Caspian Sea (with change in nutrient levels and decline of phytoplankton predator) and also human activities (i.e. water balance of ships and discharge of sewage) are severely impact on seasonal dominant species, pattern of species composition and relative abundance of species. These changes mainly accompany with appearance of new and harmful species (with the ability of severe proliferation) and displacement of native and dwell species

Determination of chlorophyll-a fluctuations and its relations with abiotic factors and phytoplankton community with emphasis on bloom potential in the southeast Caspian Sea water (Mazandaran-Goharbaran) in order the feasibility of marine cage culture

Concentration of chlorophyll-a and quantitative feature of phytoplankton are major concern in primary production estimation and prediction of probably algal blooms in aquatic ecosystems. The subject has important role in development and sustainable exploitation of marine culture. The goals of the project are study of chlorophyll-a concentration changes and its relations to variations of phytoplankton community structure parameters and abiotic factors (environmental and nutrients matters) in the costal waters of the Caspian Sea- Goharbaran region during 2013-2014. Monthly water samples were collected from different layers (surface, 5 and 10m) and depths (5, 10 and 15 m). The minimum mean (±SE) of abundance and biomass reported in spring (39± 9 million cells/m^3) and summer (94± 40 mg/m^3) respectively. The results showed maximum abundance (553± 58 million cells/m^3) and biomass (1209± 106 mg/m^3) in winter season. The minimum and maximum mean (±SE) values of chlorophyll-a recorded in spring (0.60± 0.05) and autumn (4.56± 0.23) mg/m^3, respectively. The changes trend of field chlorophyll-a concentration was confirmed by satelit data. Bacillariophyta showed the highest percent abundance in all seasons except in summer which it was for chlorophyta phylum. Pyrrophyta was the second dominant phylum in winter as well as spring; however its contribution in phytoplankton abundance of winter was low. The first dominant abundance species in spring, summer, fall and winter were Prorocentrum cordatum, Binuclearia lauterbornii, Thalassionema nitzschioides and Pseudonitzschia seriata respectively. Based on the results the species of Prorocentrum (scutellum+ proximum+obtusum) in spring and fall seasons, Cyclotella menenghiniana in summer and Pseudonitzschia seriata in winter showed the highest role in phytoplankton biomass forming. chlorophyll-a concentration showed significant Pearson correlations with biomass of total phytoplankton, bacillariophyta, pyrrophyta and chlorophyta phyla, dominant species, size cells of dominant species, water temperature, clearancy, nutrients matters. The study showed that chlorophyll-a cells content of winter dominant species was lower than fall dominant species. The Change of seasonal taxonomic phytoplankton pattern showed important role in relationship between chlorophyll-a cells content with biotic and abiotic factors. Meanwhile the values of temperature, nutrient matters, pH, pattern of dominant phytoplankton species showed significant roles on decoupling between chlorophyll-a and biomass changes pattern. The critical time of algal bloom recorded from September to January and March based on chlorophyll-a concentration. Spatial critical algal bloom was more obvious on surface water from October to December based on chlorophyll-a concentration. Pseudonitzschia seriata and Binuclearia lauterbornii species classified in medium bloom threshold (in winter and summer respectively) in all sampling depths. However Thalassionema nitzschioides (in fall) was in medium bloom threshold in 10 and 15m depths. As conclusion, in order to estimate logic primary production and predict algal blooms in the cage and pen culture sites it is necessary that all phytoplankton parameters such as chlorophyll-a concentration, biomass, abundance, shape, size, biological and ecological chracterstics of dominant species are considered. Because changes in the chlorophyll-biomass relationship could lead to obviouse errors interpretation of results and as well as unexpected field observations

Study on abundance and diversity species of phytoplankton with emphasis on potential of algal bloom in the southern part of the Caspian Sea-Mazandaran Providence

This study was conducted to determine of phytoplankton abundance and diversity of water and their spatial and temporal fluctuations in the Mazandaran coastal of Caspian Sea in 6 months, at 4 transects (Tonekabon, Nowshahr, Babolsar, Amirabad) during different season of 2012-2013. 72 samples were collected at surface layer of water in 5, 15 and 30 m depths. The samples were analyzed based on the standard methods. 112 species contributed in phytoplankton community structure which where classified in 9 phyla namly: Bacillariophyta (42 species), Pyrrophyta (18 species), Cyanophyta (14 species), Chlorophyta (15 species), Euglenophyta (11 species), Cryptophyta (2 species), Chrysophyta (3 species), Haptophyta (1 species) and Xantophyta (1 species). Meanwhile small flagellate algae with Maximum Linear Dimension (MLD) <10 µ observed which they classified in small flagellates. Mean annual phytoplankton abundance with standard error obtained 164±32 million Cells/m^3. Seasonal study showed that phytoplankon abndance of summer was 1.5 folds of spring. The value in auttuman was same as spring, however it increased sharply in winter. The mean phytoplankton abundance of winter was 5 folds of the other seasons. Mean phytoplankton abundance of Tonkabon and Nowshahr (west transects) were 1.6 and 2 folds of Amirabad (east transect), respectively. Bacillariophyta with 89 percent of total abundance was the predominant phylum and Pyrrophyta was the second one. The third and fourth of dominant phyla were Cyanophyta and Chlorophyta, respectively. Chrysophyta and small flagellates showed equal percentage of abundance (1.4 percent of total abundance). Monthly study showed that Chaetoceros throndsenii was the first dominant species in Ordibehesht, Tir and Shahrivar. However, the first dominant species in Aban, Day and Esfand were Thalassionema nitzschioides, Skeletonema costatum and Pseudonitzschia seratia respectively. Mean phytoplankton biomass calculated 156.5 ± 18.1 during the study period. The mean of biomass was higher in summer and winter than the two other seasons. Phytoplankton biomass was formed mainly by Bacillariophyta and Pyrrophyta in all seasons. The highest biomass were belonged to Cyclotella meneghiniana and Coscinodiscus jonesianus (Bacillariophyta) in spring and summer respectively.While in fall and winter Prorocentrum proximum was in the first place of dominat species. Small size and flagellates species of different phyla (Chrysophyta, Bacillariophyt...) had importance role for determination of ecological and water quality conditions during spring to autuman. The increasing of phytoplankton abundance within these times indicates to regeneration of nutrients or entrainment of nutrient-rich deep water. Dominant species were observed in single forms, small filament and loose colonies during spring to autuman. However, these form shifted to fair-long chains form in winter which it indicates to nutrient-rich water was brought to the surface by vertical mixing process. It seems that environmental stress and instability of ecosystem was benefit to Chaetoceros throndsenii and Pseudonitzschia seriata which are known as species with bloom potential. Ability of reproduction in sewage environment (Chaetoceros throndsenii) and toxin production (Pseudonitzschia seriata) are the ecological and physiological significant characters of the two species

Study on distribution of the Ctenophore Mnemiopsis leidyi in the Caspian Sea (Iranian Coasts)

In the early 1980s, an alien ctenophore Mnemiopsis leidyi already known as a gelatinous zooplankton was transported (likely via ballast waters) to the Caspian Sea from its introduced or native water of the Black Sea or western Atlantic which caused negative impacts. In this report, distribution of M. leidyi, planktonic and benthic organisms had been investigated in the Southern Caspian Sea (Iranian waters) in 6 transects consisted of Lisar, Anzali, Sefidroud, Nowshar, Babolsar and Amirabad at 26 stations during 2005 and 2006. As a whole, 1422 samples had been analyzed included 258, 346, 217, 117 and 484 belong to ctenophore, phytoplankton, zooplankton, benthos and physicochemical parameters, respectively. M. leidyi abundance and biomass were fluctuated between 284-2751 ind.m^-2 and 16.9- 390/9 g.m^-2 respectively in 2005 while maximum abundance and biomass were recorded in autumn and minimum in winter. In 2006, its mean abundance and biomass were 184-2150 ind.m^-2 and 9.1- 209/8 g.m^-2 respectively. M. leidyi maximum abundance and biomass were noted in summer and its minimum in spring and winter months. Overall, mean M. leidyi abundance and biomass were recorded in 20 m within 1202 ind.m^-2 and 139.5 g.m^-2 respectively. Maximum size of the ctenophore was recorded as 55 and 60 mm in 2005 to 2006 respectively, while less than 10 mm length frequency consisted 83.16 and 82.88 per cent of total population. Spatial_ temporal distribution of M. leidyi in different regions showed it was more abundant in west and east (714- 4494 ind.m^-2) ratio to central parts (13-1519 ind.m^-2) of the Southern Caspian Sea. Species composition of zooplankton had shown the negatively impacts of M. leidyi invasion in the period of sampling as the only 17 holozooplankton were determined with Rotatoria (7 species), Copepoda (4 species), Ciliophora (4 species) and cladocera (1 species). Zooplankton maximum abundance and biomass were recorded in February (3039742901 ind.m^-3 and 372.1575.4 mg.m^-3) respectively and its minimum were in July (12211601 ind.m^-3 and 6.9 7.7 mg.m^-3) respectively which was belonged to Rotatoria (76%) and Copepoda (10%). In this study, 21 species of benthic fauna were deter minted belong to Pseudocumidae (5 species), Gamaridae (4 species) Amphartidae (3 species), Oligochaeta, Balanidae, Xantidae, Nereidae, Scarbicularidae, Carididae, Mytilidae, Herpobdellidae and Chironomidae (each 1 species). Oligocheata was recorded with maximum abundance (943 2502 ind.m-2) and Bivalve consisted of higher biomass (68.7162.5 g.m^-2). From five phyla of phytoplankton, 172 species were determined of Chrysophyta (74 species), Cyanophyta (32 species), Chlorophyta (32 species), Pyrrophyta (24 species) and Euglenophyta (13 species), in which Chrysophyta and Pyrrophyta were noted as main groups with their maximum abundance (up to 65%) and biomass (93%). Maximum water temperature was recorded in August with 29.52.5 ֯C and minimum in February by 9.31.3 ֯C. Mean value of salinity was 12.010.90 ppt, secchi disk ranged between 0.2 to 7 m and oxygen demand varied from 5.95 to 10.54 mg. l^-1). Moreover, silicate concentration was recorded between 200 to 300μg.L^-1, Phosphate measured from 31-47 μg.L^-1, Ammonia varied in 10-29 μg.L^-1, Nitrite (0.6- 1.7 μg.L^-1), Nitrate (0.06-4.20 μg.L^-1, which mainly accumulated in coastal waters of the southern Caspian Sea

A comparative study of plankton and pelagic fishes in the southeast Caspian Sea (Mazanderan-Goharbaran)

Region South East of the Caspian Sea (area Goharbaran) having valuable resources biological flora and fauna, the diversity of commercial fishes, especially reserves the exclusive sturgeon as well as reserves abiotic such as oil and gas resources and transit of goods through Bandar Amirabad to Central Asia , the ecological conditions for the implementation of the project is very necessary. The aim of this study was to determine species composition, spatial and temporal distribution of plankton and fish of this region. Plankton sampled from different depths (5, 10 and 15 m) were carried out. Sampling of phytoplankton did by Ruttner and sampling of zooplankton did by net with mesh size 100 microns. The fish were sampled monthly from December 2013 to July 2014 and within months was carried out. From livestock gill Monofilament.. In this study, a total of 130 species of phytoplankton of 7 filums Bacillariophyta (60 species), Pyrrophyta (23 species), Cyanophyta (22 species), Chlorophyta (14 species), Euglnophyta (9 species), Haptophyta (1 species) and Chrysophyta (1 species )and 24 species of zooplankton branch of Copepoda (5 species), Rotatoria (7 species), porotozoa (3 species), Cladocera (9 species), and Meroplankton (2 species) of larvae of Cypris Balanus and bivalves Lamellibranchiate larvae and 256 fish Acipenser persicus at 5, Alosa braschnikowi 71 number, Alosa caspia 40 number, Benthophilius lipidus 1 number, Cluponella cultriventris 72 number, Cyprinus carpio 1 number, Liza saliens 15 number, Neogobius bathybius 1 number, Neogobius caspia 5 pcs, Neogobius flauviatilis 19 number, Neogobius gorlab 6 number, Rutilus kutum 14 number, Rutilus rutilus 2 pcs, vimba vimba 4 number was observed.Different ecological conditions appointment dietary needs and relationships of organisms and their adaptations to the environment, the density and distribution of different species of phytoplankton, zooplankton and fish specifies.Also the Caspian Sea due to the type of biological species and number of endemic species (42%) in addition to comb jelly invasion, were force of the effects some species like Gloeotrichia Echinulata and as a result, now or in the future, more species will be observed and recognized will be of most interest. Also Psedonitzschia seriata ability to produce Domick acid that can be hazardous to aquatic animals and even human, was in Goharbaran area. This was considered for fishes of the southern Caspian Sea and ecological distribution of most species depends on the region. The abundance of two species of whitefish and pelagic fish in Ghahrebaran region is more than the whole Caspian Sea. On the other hand, the dominant phytoplankton of this region is Bacillariophyta and dominant zooplankton is Copepoda, which shows the goodness of these plankton branches, and by changing the various factors as the different terms of receiving solar energy and resulting in temperature and water currents can cause seasonal differences in the density of the Bacillariophyta branch and also the Copepoda, therefore one of the most important factors is season, and in the winter, when the aquatic rotation of this ecosystem increases, it increases the nutrients and moves it from the floor to the water column, and as a result, increasing the amount of silica in various levels of water can affect the nutrition of fish