In this study 16 groups of Zooplankton belong protozoa, arthropoda, rotifer and cyliophora were investigated. The number of these Zooplanktons were accounted in m3 and also their biomass (mg/m3) was measured. The average biomass of Zooplankton was measured 531. 74, 30. 77, 225. 07 and 96. 26 mg/m3 respectively and the total was attained 883. 83 mg/m3. The maximum and minimum biomass of all Zooplanktons was estimated in November and July, 3446. 23 and 6 mg/m3 respectively. Furthermore, the maximum and minimum numbers of Zooplanktons were found in September and July which were 48. 4 and 0. 002 millions respectively and the average number was 8. 4 ind/m3.

This study was carried out to determine seasonal variation and Zooplankton community structure in Karatas Lake, Southern Turkey. Zooplankton samples were collected seasonally between 2002 and 2003 in two stations using a Zooplankton net of 55-mm mesh size. A total of 42 taxa were identified, including 19 taxa (45.2%) Rotifera, 16 taxa (38.1%) Cladocera, and 7 taxa (16.7%). Copepoda. Among them, Keratella quadrata, Asplanchna priodonta from Rotifera, Daphnia longispina, Ceriodaphnia quadrangula, Chydorus sphaericus, Coranatella rectangula from Cladocera, and Eudiaptomus drieschi, Eucyclops speratus from Copepoda were dominant species. Spring and autumn seasons were found to be the most similar by using Sorenson index value.

Anzali wetland is one of the most important places for migratory fishes. Zooplankton organisms are the first consumers in the ecosystem. They are perfect food for the larvae of fishes. Six stations from different areas of wetland were examined for the study of Zooplankton population during March 2011 to April 2012. Sampling was done by tube (PVC) and passing through of 30 micron plankton net. The samples were identified and counted by inverted microscope. According to the results, 60 Genus and 6 phylum (11, 31, 10, 2, 1, 1, 1, 2 genus of phylum Protozoa, Rotatoria, Arthropoda, Gastrotricha, Mollusca, Tardigrada, Nematoda, Porifera, Annelida) respectively were identified. The results showed that the maximum annual average density of Zooplankton was observed with 2497±687number per litre in Karkan station and the population was more in the summer than in other seasons. Density of Rotatoria, protozoa and superclass Copepoda were 48%, 45% and 6% respectively. Results showed the population structure of Zooplankton did not change much compared to past studies (due to improper environmental conditions), excluding Protozoa but the diversity of all Zooplankton group is extremely declined. Kruskal Wallis test showed there was not significant difference between density of Zooplankton in different stations, months and seasons (p>0.05), but significant differences were found between densities of different Zooplankton phylum (p<0.05).

In order to identify, density and distribution of Zooplankton and its changes over from winter 2009 to summer 2010 in the 3-stage sampling was performed. A sample stuck with huge plankton net 55 microns (Judy Net) was performed, than 4% formalin fixed samples of an inverted microscope in a laboratory study. Investigation totally distinguished 31 Genus in 6 Phylums among of genus. In this regard, the following series of Protozoa and branches Rhizopoda 5 genus, Ciliophora 2 genus, branch of Gastrotricha 1 genus, Nematoda phylum 20 genera Rotatoria branch and the branch Arthropoda and the order Cladocera 2 genus with embryonic stage and the category Copepoda 1 genus with them nauplius and were Chironomidae family respectively. The combined population of the lake Zooplanktons Arasbaran most diverse branches of the genera Rotatoria Polyarthra, Synchaeta, Brachionus, Keratella, and Trichocerca the greatest diversity and abundance of this category is in the spring. In total, an average of 1, 179 per liter Rotatoria 69 percent in the lake had the largest population. Between Zooplankton abundance at different stations and months there was a statistically significant difference (P<0. 05). In the summer season with another two seasons showed significant differences (P<0. 05). Biological studies showed that plankton production potential Rotatoria branch in the lake at almost a high.

The present paper deals with a toxin producing phytoplankton (TPP) -Zooplankton interaction in spatial environment in the context of phytoplankton bloom. In the absence of diffusion the stability of the given system in terms of co-existence and hopf bifurcation has been discussed. After that TPP-Zooplankton interaction is considered in spatiotemporal domain by assuming self diffusion in both population. It has been obtained that in the presence of diffusion given system becomes unstable (Turing instability) under certain conditions. Moreover, by applying the normal form theory and the center manifold reduction for partial differential equations (PDEs), the explicit algorithm determining the direction of Hopf bifurcations and the stability of bifurcating periodic solutions is derived. Finally, numerical simulations supporting the theoretical analysis are also included.

The need for predictive water quality modeling has arisen largely as a result of increased eutrophication of lakes throughout the world. In 1919 Nauman introduced the concept of oligotrophy and eutrophy, distinguishing oligotorophic lakes with little panktonic algae and eutrophic lakes containing much phytoplankton. The phytoplankton consist of the assemblage of small plants having no or very limited powers of locomotion. A variety of formulations have been developed to represent the effect of temperature, light, and nutrient on phytoplankton growth. A number of processes contribute to the loss rate of phytoplankton. These processes are: respiration, excretion and predatory losses. The Zooplankton includes animals suspended in water with limited power of locomotion. Phytoplankton as well as Zooplankton are usually denser than water, and constantly sink by gravity to lower depths. System dynamics is a method of solving problems by computer simulation. The typical purpose of a system dynamics study is to understand how and why the dynamics of concern are generated and to search for managerial policies to improve the situation. In this paper phytoplankton and Zooplankton are simulated by system dynamics approach. Then we integrated a limiting nutrient into our phytoplankton-Zooplankton scheme to complete our fundamental picture of how nutrient/food-chain interactions are modeled.

Anzali wetland is one of the most important ecosystem for fishes spawning and Zooplankton groups are the first consumer in this ecosystem.They are the perfect food for the larvae of fishes. Zooplankton status was evaluated in 10 stations of different areas of the Anzali wet land during March 2014 to February2015. Sampling was done by tube (PVC) and passing through of 30 micron planktonic net. The samples were identified and counted by invert microscope. A total of 72 Genus of phylum Actinopoda, Rhizopoda, Ciliophora,, Rotatoria, Arthropoda, Gastrotricha, Mollusca, Tardigrada, Nematoda, Porifera, Annelida) were identified. The results showed that the maximum and Minimum annual average density of Zooplankton was observed with 9667±12383 and 312±1539 ind.lit-1 in Komeh Sheijan station and West Wetlands Center station Respectively. The population was more in the summer than in other season phylum of Rotatoria, Rhizopoda, Ciliophora and superclass Copepoda formed 59, 8, 30 and 3 percent of the density respectively. According to the results the populationof Zooplankton is ncreased compared to past studies. According to the statistical analysis Kruskal Wallis there were not significant differences between density of Zooplankton in different stations, months and seasons (p>0.05), but significant differences were found in between different phylum (p<0.05). Overall, the results showed that the Anzali wetland has Eutroph condition.

In this study, the status of trophy of Choghakhor wetland was investigated using Zooplanktons. Sampling was performed in 4 seasons and 10 stations since April 2010 to March 2011. Spacing between stations adjacent was considered 1km to each other.Zooplankton sampling was done horizontally (2m) using closing net with an aperture size of 55 microns at depth of 30 cm. Results showed that the most abundant family of Zooplankton communities are rotifers (9 families and 16 genera), Branchiopod (3 families and 5 genera) and copepods (1family and 3 genera). Rotifer was the most abundant taxon in all seasons. Abundant of keratella sp. in spring, Monostyla sp.in summer and autumn and Polyarthra sp. in winter were significantly more than the other species (P<0.05). And also Shannon and Simpson diversity indices in autumn, were significantly higher in comparison with other seasons (P<0.05). The highest level of chlorophyll a in summer and fall were 20.92 and 22.63 mg per cubic meter respectively. The annual average of that in the wetlands was determined 75.18 mg per cubic meter, showing that the trophy of wetland was high. In addition, evaluation of trophy indices based on phosphate, nitrate and transparency parameters, demonstrated that trophic state of wetland was in eutrophic condition. Increases in Abundant of Polyathra, Brachionus, Monostyla, Keratella geniuses in this condition can be a sign of eutrophication happening in this wetland.