The seasonal fluctuation of Cyanophyta in the southern Caspian Sea

The objective of this study was to evaluate the seasonal fluctuation of density and biomass of cyanophyta in different water temperatures in the southern Caspian Sea in 1996 and 1999-2000. 432 samples of phytoplanktons were collected from 18 stations in coastal zone (depth less than 10 m). As a result, 11.1% (9 species from 81) and 15.6% (25 species from 160) of total phytoplanktons were cyanophyta in years 1996 and 1999-2000, respectively. The maximum density and biomass (1.65x106/m3 , 4.09 mg/m3) of Cyanophyta were found in the western region and in warm seasons (spring and summer). On the other hand, in cold seasons (autumn and winter), the maximum density and biomass (1.5x105fm3, 3.36 mg/m3) were found in the eastern part of the Caspian Sea. In years 1999-2000, the maximum biomass and density of Cyanophyta were found in eastern, central and western parts of the Caspian Sea in spring and summer, meanwhile in autumn and winter, they were found with maximum density and biomass in the eastern part. In all seasons, the minimum and maximum water temparture were measured in the western part and eastern part of the southern Caspian Sea, respectively. The results showed that the most density of cyanophyta were measured in summer that can be related to the increase of temperature and daylight. The non-parametric statiscal analysis indicated that there were no significant difference between biomass and density of cyanophyta in years 1996 and 1999-2000. As a conculsion, the population dynamic of cyanophyta were mostly affected by combination of enviromental factors than effect of a single factors sperately (such as temperature)

Lingulodinium machaerophorum expansion over the last centuries in the Caspian Sea reflects global warming

This article is made available through the Brunel Open Access Publishing Fund. Copyright @ Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene

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

Study on physico-chemical characteristics of Azad dam reservoir (Sanandaj) in order to fisheries activities

Dam reservoirs have important rules in aquaculture and fish farming in many countries. In this regard, water samples of Azad Dam reservoir (Sanandaj) were collected at five stations from July 2015 to June 2016. Then, the results of 18 physico-chemical parameters were compared with the aquaculture standards and thresholds. Results showed that thermocline and oxycline was started from June and they vanished in December. Maximum level of thermal and oxygen stratified were registered during August and June, respectively. Mean of the most physico-chemical parameters were significantly different between surface and bottom layers (T-Test, p<0.05). Mean of temperature, dissolved oxygen, total alkalinity, total hardness, pH, total suspended solid, total dissolved solid and nutrients were in range of standard threshold of different countries. As a result, based on physico-chemical parameters and with proper management decision, the dam reservoir could be considering suitable for standard pattern of aquaculture activities

Features of phytoplankton community in the southern Caspian Sea, a decade after the invasion of Mnemiopsis leidyi

Phytoplankton study has become more significant in the Caspian Sea due to the occurrence of ecological events such as algal blooms and the introduction of the invader species(Ctenophore, Mnemiopsis leidyi). A seasonal study was conducted to investigate the features of phytoplankton community one decade after this invasion in the Iranian coast of Caspian Sea during 2009-2010. According to the results, 195 species in eight phyla of phytoplanktons were identified. In spring, Bacillariophyta and Pyrrophyta were the dominant phyla with 40 and 29% of total abundance, respectively. In summer and winter the dominant phyla were made by Cyanophyta (92%) and Bacillariophyta (94%), respectively. The Bacillariophyta (57%) and Cyanophyta (28%) were the first and second dominant phyla in autumn . It seems that the ctenophore invasion into the Caspian Sea (due to the changes in nutrient levels and decline of phytoplankton grazers) and human's destructive activities play an effective role on phytoplankton community during the period. These changes were mainly accompanied with appearance of new and harmful species (with the ability of severe bloom making) and consequently, displacement of native species in this semi-enclosed ecosystem

Eutrophication trend of southeast Caspian Sea water (Mazandaran-Goharbaran) based on environmental and biotic parameters using single and multiple variables in order to feasibility of marine cage culture

The aim of this project is to study water quality and the trophic status at different months and depths in the southeast Caspian Sea-Goharbaran based on environmental parameters and nutrients during 2013-2014 in order the feasibility of fish cage culture. Results showed that water temperature, transparency, pH, dissolved oxygen, BOD5, COD, total alkalinity and TSS were varied 9.00-29.00C, 0.50-12.00 m, 8.05-8.74, 5.76-12.85, 14-101, 21-195 and 0.00-0.12 mg/l at the different months and depths, respectively. In addition, the values of NH^4+, NH_3, NO^2-, NO^3- and PO^4-3 were 0.007-0.051, 0.001-0.010, 0.002-0.015, 0.043-0.477 and 0.014-0.077 mg/l, respectively. Chl-a concentration was recorded as 0.060-8.02 mg/l. Scaled and unscaled trophic indices were equal to 3.42-5.52 and 2.61-5.85, respectively. The proper temperature for cultivation of salmonids species in this area began from October to March. The range of the standard of pH and dissolved oxygen level for fish farming cage were 7.80-8.50 and >5 mg /l that in current study results of pH and dissolved oxygen which were consistent in the current study. Various forms of nitrogen (ammonium, nitrite and nitrate ) at the different layers were acceptable and less than the threshold limit of Australia and New Zealand. The results of the nutrients concentrations compared with data from the reference years (1996-1996 ) in the Caspian Sea (Goharbaran region) showed that this ecosystem passed from oligotrophic status and shifted to mezotrophic and eutrophic condition. As a conclusion, although nutrients concentrations were acceptable in terms of fish farming cages in this region, some parameters such as chemical oxygen demand and transparency are not suitable for aquaculture industry. Meanwhile, based on various trophic levels, this ecosystem (Gohrabaran region) has a mezotrophic status with a high risk of eutrophication

The feasibility of creating a natural habitat for spawning, bony fish in the Caspian Sea in order to preserve biodiversity and genetic risk

The purpose of this study was to investigate the possibility of natural reproduction of indanger fish in the southern Caspian Sea in Tajan, Haraz,Sardabrood and Chalos rivers, and identify suitable habitats for this species in the study area as a genetic reserve.Sampling of physical and chemical parameters of water, macrobenthic invertebrates and fish fauna was conducted seasonaly in each rivers at selected stations from febrary 2010 during one year. Macrobenthic invertebrate sampling were used bySorber sampler and fish was collected by gill net and electroshocker set with a voltage of 1.7 A and 100-300 V. A total of 53 taxa of macrobenticinvertabrateshave been identified in the four mentioned rivers, in which Tajanriverconsisted of 47 taxa with highest richness.20 species of fish were determined in the studied rivers that 6 of them were non-native species.The results showed that the predominant identified fish species were native in the river. The fish species diversity increases as one moves from the headstream towards the estuaries of the two studied Sardabrud and Chalus rivers.The results of this study showed that the relative abundance of fish species resistant to pollution and hard environmental conditions were much more that sensitive species. physicochemical parameters of water such as; water temperature, DO, BOD5, pH, TSS, TDS, EC, turbidity, nutrients, biodiversity index such as Shanon index, EPT, HFBI, EPT/CHIR, nutrition functioning group and present or absent of fish species showed that there are significant decrease in water qualities from upstraem ratio to down stream (For example, in Tajan river water turbidity varied from 0 at station 1 to 333 NTU at station 6, Which is strongly influenced by sand workshops. As well as the activities of a significant impact of fish farming workshop on the Haraz river water quality). The minimum of HFBI index was 2.84 at station 1 and the maximum was recorded at station 5 with 6.01, and there is not any possibility to natural reproduction of migrated species that are dominant and indanger at downstream. Conditions for natural reproduction of this species in the rivers of srdabrood and Chalus there is to some. In Shahid- Rajaei dam the maximum relative abundance of fish species belonged to Capoeta capoeta, Luciobarbus capito and Squalius cephalus, respectively. These species have different age, length and weight stuctures at Shahid- Rajaei dam inhabitant, and the resourval of this dam and it,s upstream have been preparing auch a favorabile condition that seems there are potentioal of introductionand inhabitant of some of the Migratory and indanger fish species such as Barbels, Sturgeon, Alburnus chalcoides and etc. as genetic reserve for biodiversity preservation

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 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