Gomishan Wetland which is located at the extreme south eastern part of the Caspian Sea has very important characteristics. The Zooplanktons of the wetland are determined in 15 groups, belonging to 5 phyla. The density of these microscopic animals is studied within 5 chosen stations and during 12 continued months, via sampling, laboratory and statistical investigations. The seasonal variations were noticeable. The minimum density of the Zooplanktons is found in February and then in January. The maximum density for most of the groups was observed from the beginning of the summer until the mid autumn. The annual mean density for any 15-zooplankton groups, as well as, the minimum and maximum density, with %95 confidence limits, are calculated for all of the stations and also the whole wetland. The spatial distribution of the individuals within the population of each of the groups is computed, according to regular, contagious or random distributions. Diversity indices are calculated for the Zooplanktons of each station. Comparison of the wetland, with the south eastern Caspian Sea, from the point of view of zooplankton density and diversity is also given in the paper. As a result of the study, the zooplankton density of the wetland is quite higher than the neighboring sea.

The Zooplanktons were studied in spring, autumn and winter in the southern Caspian Sea in 1996. Sampling carried out in four season. In each season, 180 specimens were identified and their frequency calculated per m3. 55 species of Zooplanktons were identified including 55% Cladocera, 15% Copepoda and 11 % Rotatoria, 9% other groups such as meroplanktons. The maximum species diversity was observed for Cladocera and the maximum frequency were observed for Copepoda. The Copepoda affected on abundance of Zooplanktons as this frequency included in spring, summer, autumn and winter that were 38% to 97%, 22% to 92%, 71 % to 99% and 31 % to 92%, respectively. In summer, the Copepoda and lamellibranchiata larvae had main role in formation of zooplankton population in western region of the southern Caspian Sea, but in autumn, 70% of zooplankton population were copepods. The frequency of Zooplanktons in spring, summer, autumn and winter were calculated 4081 to 20143; 7812 to 65741; 10850 to 34406 and 4510 to 20576 ind./m3, respectively. The maximum biomass was observed during summer with 200 mg/m3.

Mnemiopsis leidyi was sampled from December 2003 to March 2005 in 11 stations located along four regions AnzaH, Khazarabad, Tourkman and Gorgan Bay using METU net in the Iranian coasts of the Caspian Sea. Study of stomach contents of Mnemiopsis leidyi showed that Acartia sp. belonging to Copepoda and Lamellibranchia sp. had the highest frequency comprising 66% and 13% of food items taken by the organism respectively and the least food items taken were Balanus nauplii, Rotatoria, Tintinnopsis and Podon polyphemoides. The maximum mean abundance of food item was Acartia sp. which was shown to be present in stomach content of Mnemiopsis leidyi caught in different depths, seasons and regions in the Iranian coasts of the Caspian Sea. For the M leidyi larvae, the highest amount of food item was Acartia sp. and Lamellibranchia sp. with an average of 44% and 32% and the maximum abundance of food item for juvenile and mature Mnemiopsis leidyi was also Acartia sp. with an average of 67.5% and 66%. The results showed that the main food item for Mnemiopsis leidyi is Acartia sp. of the Copepoda. Hence, Mnemiopsis leidyi feeding has an important effect in declining zooplankton populations.

This survey was carried out by R/V Guilan ship with a conical plankton net of 100 micron mesh by vertical hauls at different stations and depths of 5, 10, 20, 50 and 100m in 2010. In this study, 16 species formed the zooplankton community including 4 species of Copepoda, 4 species of Rotatoria, 2 species of Protozoa and 4 species of Cladocera from Holoplanktons and 2 species of Balanus sp and Lamellibranchiata larvae from Meroplanktons. The annual results revealed that the mean abundance of zooplankton were 5477±5815 ind/m3 in spring but the maximum biomass (64.58±124.61mg/m3) was in winter that was affected by Rotatoria. The maximum mean abundance and biomass of Copepoda were in summer that were 2830±2342 ind/m3 and 22.52±21.78 mg/m3, respectively and the abundance decreased gradually since autumn and reached the least in winter but increased since spring. The mean maximum abundance of Cladocera (115±142 ind/m3) was in spring but it gradually decreased, The Protozoa constituted the least community and biomass of zooplankton in southern area of Caspian Sea. The zooplankton community also was affected by Meroplanktons including Cirripedia and Lamellibranchiata Larvae in spring and the Rotatoria contributed highly in zooplankton community in winter with the mean abundance and biomass of 2604±5876 ind/m3 and 50.71±115.33 mg/m3 respectively. It was observed the reduction trend in abundance from surface depths to deeper depths in whole of the year. There were 75% of zooplankton community in stations with 5 to 20m depth and 25% of community in stations with 50 to 100m depth in spring, and also 74% in stations with 5 to 20m depth and 26% in stations with 50 to 100m depth in summer, 73% in stations with 5 to 20m depth and 27% in stations with 50 to 100m depth in autumn and 85% in stations with 5 to 20m depth and 15% in stations with 50 to 100m depth in winter. In analysis of different area of southern basin of Caspian sea the maximum abundance was observed in west in spring, summer and winter which were 7514±8115 ind/m3, 3909±2609 ind/m3 and 8129±11587 ind/m3, respectively. There was 2283±2134 ind/m3 in center area in autumn. The annual statistical analysis revealed that, there was significant difference in total zooplankton community between sampling stations, depths and layers in whole of the year.

Wetlands are among the most productive ecosystems in the world. Zooplanktons are important organisms in wetlands because they are nutritious food for the fish larvae. The nutritional value of zooplankton varies based on species composition, community structure and physicochemical parameters of water in different seasons. This study aimed to measure amino acids composition of freshwater zooplankton in Hanna wetland over four seasons. The sampling was carried out by vertical haul using a plankton net (140 μm, diameter of 25 cm) in the mid-season from summer 1386 till spring 1387. The dominant crustacean Zooplanktons in Hanna wetland were Cladocera (3 species of Daphnia genus and each one species from genus Moina, Ceriodaphnia, Bosmina) and Copepoda (including the genus Microcyclops, Acanthocyclops, Allocyclops, Macrocyclops, Metacyclops and Cyclops). Results showed that the average total essential amino acids (EAA) were 28.7 %, 31.0 %, 31.6 % and 34.5 % of total amino acid, while total non-essential amino acids (NEAA) were 71.3%, 69.0 %, 68.4 % and 67.0 % of total amino acid in spring, summer, fall and winter, respectively. Among EAA, arginine 8.9%, 10.7%, 4.1%, and 5.5 %: threonine 6.4%, 4.9%, 6.2%, 7.0 %: thyrosine 4.6%, 4.7%, 4.1%, 3.3 % and methionine 2.4%, 2.2%, 1.6%, 4.1 % of total amino acid respectively in spring, summer, fall and winter were in the highest average levels during study period. Correspondingly, glutamic acid 21.4%, 18.9%, 18.3%, 18.7 %: alanine 16.9%, 15.6%, 14.8%, 12.8 % and aspartic acid 12.3%, 13.0%, 12.1%, 11.3 % were the highest compared to other NEAA in zooplankton samples. The results of this study illustrated that the amino acid composition of the Zooplanktons collected from Hanna wetland vary in different seasons.

The present paper was depicted to analyze the water quality status in single terms and Zooplanktons of the Bhagirathi river. The water quality parameters were analyzed in lab. such as pH, Total Dissolved Solids (TDS), Total Hardness (TH), Chloride, Dissolved Oxygen, Calcium, Biochemical Oxygen Demand (BOD and Chloride. In the I site of the first area, the value of WQI in monsoon 55. 79, winter 31. 73 and summer 45. 66, In the site 2, the value of WQI in monsoon 61. 46, winter 38. 17and summer 46. 42, In the site 3, the value of WQI in monsoon 61. 36, winter 32. 91 and summer 47. 55 were observed. Water quality index in the all study site is good in winter and summer, but poor in monsoon season. These freshwater systems also support various forms of aquatic life. The zooplankton of our study site mainly comprised of Protozoa, Rotifer, Copepoda, and Cladocera. A total of 11 genera of Zooplanktons were observed during the study. The maximum number of Zooplanktons genera was during winter and minimum during the rainy season. The most remarkable aspect of River Bhagirathi at these sites seems to be the tremendous potential to heal the health of the entire river ecology that gets damaged due to insufficient water released from the hydro-electric power project after the dam wall into the main river channel. Immediate steps need to be taken to restore the ecological balance-mainly in main river channels after the dam wall of hydro-electric power projects.

In order to study the growth rate of stellate sturgeon, three earthen ponds with 2 hectares area were selected randomly. Two ponds were treated with 16 tons organic fertilizer and 40 kg Daphnia. The total culture period was considered 35 days. The physical and chemical parameters of water and also the density of Zooplanktons and benthos were measured during the rearing period. Apart from these factors the gastrosomatic index (GSI), daily growth rate and the condition factor of the fingerlings were also determined in order to assess the output of each pond. On the basis of the statistical analysis conducted, no significant difference was observed in the physical factors of the water in the three ponds but for nitrite values were significant.The major productivity of Zooplanktons and benthic organisms were Daphnia (D. magna and D.pulex), cyclops and nauplii of cyclops.

One of the reasons for poor performance of filters is their being backwashed. The purpose of this study is to evaluate filtration process and sand filters operation after being backwashed through examining turbidity and Zooplanktons in Esfahan water treatment plant. This study was conducted during 4 months in the sand filters (phase 1 & 2) of the treatment plant. Turbidity and microscopic counting were studied to assess the performance after filtration. The average for turbidity variations and nematodes & rotifers counting were evaluated in different times after backwash. Turbidity break point and Zooplanktons reduction occurred after 15-20 minutes of backwash. The number of nematodes and rotifers in phase 1 after 10 minutes increased respectively by 13 and 12 numbers per liter and within 20 minutes، it reduced to 7 and 9 numbers، respectively. Also after 20 minutes in phase 2، the number of nematodes and rotifers decreased respectively by 8 and 6 per liter. This changes were significant based on t-test (p <0. 001). Also after 15-20 minutes، filters effluent turbidity reduced to less than 0. 2 NTU. It is better to put filters in the circuit 20 minutes after being backwashed in order to restrict the number of suspended particles and organisms inside the effluent.

The present study aims to examine and identify Zooplanktons species carried by ballast tanks of the ship and discharged into Bandar Imam Khomeini waters. The samples were taken during summer 2014 from 12 ships loaded with ironstone, condensate and ironware traveled from both South America and the Southeast Asia within two seasons. For this purpose, 50 liter-three specimens was filtered by a 100 micron plankton catching net and stabilized by formalin. The specimens were detected by microscope and by using the valid identification keys. Considering to the obtained results within two seasons of summer and winter, it is found that there were totally 9 families and 18 genera transported through South America route where the greatest frequency was related to Paracalanidae with 35%, whereas in the Southeast Asia route there were 18 families and 30 genera of Zooplanktons in which the greatest frequency was found in Cyclonidae and Sididae families with 9 and 8%, respectively. By comparing both local and foreign reports related to this zone it was revealed that no species can be regarded as invasive species.

A Comprehensive hydrobiological and hydrological investigation was conducted on Hevigh River, west of Guilan Province from 2001 to 2002. Totally, 4 Phyla of phytoplanktons including 21 genera were observed. The maximum phytoplankton density belonged to the Phylum Chrysophyta with genera, Nitzchia, Diatoma, Cocconeis, Navicula and Cymbella comprising 95.7% of the phytoplankton population throughout the year. Chlorophyta ranked second with genera Scenedesmus, Cruciginia and Ankistrodesmus, comprising 2.20% of the population during the year. Cyanophyta with Oscillatoria and Euglenophyta with Euglena consisted the remaining few percents of the phytoplankton population.Zooplankton population in Hevigh River was found to be very poor, and mostly belonged to Protozoa and Rotatoria. However, 4 Phyla and 12 genera of Zooplanktons were distinguished in the River the highest density of which belonged to Protozoa with genera Arcella, Difflugia, Cyphoderia and Euglypha, comprising 64% of the total population. Rotatoria with genera Keratella, Cephalodella, Lecane and Rotaria, consisted 14% of the zooplankton population during the year. Arthropoda, Nematoda, Tardigrada were very low in numbers.