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

The study of diversity, distribution and abundance of zooplankton in the southern of Caspian Sea

This survey was carried out in 8 lines of southern area of Caspian sea consisting of Astara, Anzali, Sefid roud, Tonekabon, Noshahr, Babolsar, Amirabad and Torkman in depths of 5, 10, 20, 50 and 100m in 4 seasons (spring, summer, autumn and winter) of the year 2008. The goal of this survey was identification of different species, distribution, density and Biomass of the zooplankton community in different regions and also their frequency in the different layers and depths and the population fluctuations in whole of year. The most abundance and biomass of the zooplanktons were 28005±24212 ind./m^3 and 180.58±149.03 mg/m^3 in 5 min spring and they were reduced gradually to depths. Copepoda comprised between 9 to 16 percent, Rotatoria comprised between 5 to 13 percent and Lamellibranchiata larvae comprised between 27 to 70 percent of marin zooplanktons. The most abundance and biomass were 11746±7921 ind./m^3 and 47.07±31.96 mg/m3, 5281±5521 ind./m^3 and 29.03±31.68 mg/m^3 in 5m of summer and autumn seasons, respectively. Copepoda comprised more than 95 percent of marine zooplanktons in all of depths in these seasons. The most abundance and biomass were 19030±16518 ind./m^3 and 198.99±217.23 mg/m3 in 5 m in winter. Copepoda comprised between 17 to 49 percent and Rotatoria comprised between 32 to 70 percent of marine zooplanktons in all of depths and the abundance of other groups was not considerable in zooplankton community

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

Water quality based on the species composition and abundance of phytoplankton in Shahid Rajaei Dam- MazandaranProvince (Sari)

Shahid Rajaee Dam was constructed on Tajan River (basin of the Caspian Sea) and it is two arch typed. The major objectives of dam instruction are flood control, irrigation purposes, and electricity power. However the dam is going to supply drinking water for the people. In order to prevent threats of unsuitable water to human health risks and economic losses, it is necessary to monitor the water quality before offering it to people. Many of algal blooms happening in Dams indicate that microbial evaluation is necessary but it is not sufficient.in water quality assessmens. Therefore in order for comprehensive evaluation of water quality, phytoplankton structure and population studied in the reservoir, then some water quality indices calculated based on the obtained information. Seasonal sampling was carried out in the year of 2012. However in summer monthly sampling was performed due to the increasing of algal blooms probability. Water samples were collected in 4 stations which were located entrances of Shirin Rood and Sefid Rood to the lake of dam, Cross of the two entrances and near the crest respectively. Based on the results, 107 phytoplankton species were identified during the period of study. The species were classified in 8 divisions namely Bacillariophyta, Pyrrophyta, Cyanophyta, Chlorophyta, Euglenophyta, Chrysophyta, Xantophyta and Cryptophyta. The numbers of species were 27, 22, 17, 26, 10, 3, 1 and 1 respectively in each phylum. Maximum and minimum values of mean (SE) abundance observed in July and January, 661 (±286) and 10 (±2) million cells/m^3 respectively at the surface layer. The values for biomass were 9264(±3242) and 103(±15) mg/m^3 which were recorded at the same months. The One way analysis of abundance and biomass data showed temporal significant variances (P 0/05). Bacillariophyta and Pyrrophyta formed more than 95% of phytoplankton abundance and biomass. Abundance percentage of Bacillariophyta was slightly higher than Pyrrophyta While biomass percentage of Pyrrophyta was about 3 fold of the Bacillariophyta. 3 dominant species namely, Cyclotella meneghiniana, Goniaulax polyedra and Ceratium hirundinella formed about 70% of phytoplankton aboundance. Comparison of diversity indices (Shannon and Evenness) showed higher values in May and January; however the indices reached its lowest level (0.58 and 0.16) in August. Water quality assessment using Shannon index showed the lowest quality of water (moderately to high polluted) in July and August. This index demonstrated the highest water quality (slightly polluted) at station 1 and 4 respectively. The results of the water quality assessment using Saproby index (based on the resistant phytoplankton species to organic pollution) also indicated to organic pollution of water in the months of summer. The saproby assessment in stations categorized most of the stations in “moderately polluted” class of organic pollution except at station 4 which was in "slightly polluted" class. In conclusion, the removal (transfer) place and time of water to the water treatment plants.are impratnt because of temporal and spatial variation of water quality due to changes of phytoplankton structure in Shahid Rajaee Reservoir

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

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

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

Since phytoplankton are the base of life and productivity of aquatic ecosystems, sustainable ecological study of the Caspian Sea, particularly the distribution and identification of species composition, density and biomass, seasonal and regional variations in phytoplankton before each study seems necessary. Due to various circumstances physical and chemical rivers leading to the sea, seabed topography in different situation appears to be of primary production in the eastern and western between the Caspian Sea in the season, may be altered.Identifying species and determining the distribution and biomass of the changes and how they are affected by environmental changes and we are environmentally conscious. We also compare the current situation with previous studies, we find that the number and types of plankton biomass have been what it is. During 1389 in spring, summer, autumn and winter, in a study of 8 transects of 40 stations. In each transect from Astara to the Turkmen. 5 stations at depths of 5. 10. 20. 50. 100 m were selected for sampling. The total number of 182 species from seven branches Bacillariophyta, Pyrrophyta, Cyanophyta, Chlorophyta, Euglenophyta, Xantophyta and Chrysophyta phytoplankton were identified. Including 81 species of Bacillariophyta, 33 Cyanophyta, 25 Pyrrophyta, 31Chlorophyta, 9 Euglenophyta, 1 Xantophyta and Chrysophyta had 1 specie. Studies have shown that density and biomass of Bacillariophyta were 228 (± 471) per cubic meter × 106) and 6157 (± 290) mg per cubic meter) respectivity and Pyrrophyta were 28/17( ± 27/14) cubic meter × 106in cubic meters) and 3349 ( ± 336) mg per cubic meter) and Cyanophyta 120/40 (± 123/87 ) per cubic meter × 106 per cubic meter), biomass (55 ± 57mg per cubic meter) were the branches of the dominant phytoplankton. Abundance and biomass in different seasons have been significant differences (p <0.05). Most of Bacillariophyta (61 species) was in Autumn and then in winter (48 species). Dominant species of Bacillariophyta were Pseudonitzschia seriata, Rhizosolenia fragilissima, Stephanodiscos sp. , Melosira varians, Nitzschia acicularis and Cyclotella menenghiniana Pyrrophyta was greatest diversity of branches in summer, autumn and winter (19 species), which includes Exuviaella cordata, Exuviaella marina, Prorocentrum praximum and Prorocentrum scutllum. In the autumn density of Cyanophyta was 285.7(±137.1) cubic meters × 106 and biomass was 95(±54) mg per cubic meter) and 18 species were observed. The dominant species in this category were Oscillatoria sp., Nodularia spumigena and Oscillatoria agardhii. Most species of Chlorophyta branche in autumn and winter and summer median region with the highest density at the density of 26.2% and most of it is Binuclearia lauterbornii. Identified as the branches Euglenophyta were Trachelomonas, Euglena and Phacus that were observed in all seasons. In winter, the highest mean biomass was 9(±0.818) mg per cubic meter and the highest density of in summer was 0.5 (±0.5) in cubic meters ×10^6. In winter the depth of 10 meters and surface of Babolsar, Amir Abad and Anzali, a kind of Chrysophyta and in surface of Tonekabon and Anzali a species of Xantophyta were observed that had negligible density and biomass

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

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

The study abundance, distribution and diversity of zooplankton in the southern of Caspian Sea

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 4 seasons of 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/m^3 and 5131±7908 ind/m^3 in spring and winter respectively which were more than other seasons but the maximum biomass (64/58±124/61mg/m^3 ) was in winter that was affected by Rotatoria. The maximum mean abundance and biomass of Copepoda were in summer that were 2830±2342 ind/m^3 and 22/52±21/78 mg/m^3 ,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/m^3) was in spring but it decreased gradually, so it reached to less than 3 ind/m^3 in summer. 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/m^3 and 50/71±115/33 mg/m^3 respectively.Other than Copepoda, other planktonic groups contributed lowly in zooplankton community. 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/m^3, 3909±2609 ind/m^3 and 8129±11587 ind/m^3, respectively. There was 2283±2134 ind/m^3 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