ALBERT

Description: This study was conducted to determine physico-chemical characteristics of water and their spatial and temporal fluctuations in the Mazandaran coastal of Caspian Sea in 6 months, four seasons at 4 transects (Tonekabon, Nowshahr, Babolsar, Amirabad) during 2012-2013. 72 samples were collected at surface layer of water in 5, 15 and 30m depths. Then the sampls analyzed based on standard methods. Results showed that the mean of water and air temperature were 19.46±0.85 and 20.25±0.78 ◦C, respectively. Minimum and maximum of water temperature were recorded in winter (7.00) and summer time (28.10). Mean of salinity was 12.35±0.13 ppt. The maximum salinity was recorded in summer and minimum in winter in all transects. Mean of transparency (SD) in the present study was 2.63±0.18m. The mean of pH was observed 8.51±0.02 which was higher than the pervious sampling periods. The mean of DO was observed 6.00±0.07 ml/l during sampling period. Annual concentration of dissolved inorganic nitrogen (DIN= NH4 +, NO2-, NO3-) has a fairly wide variation in diferents months and transects. Percentage of nitrogen components out of DIN were varied 6-53, 0.14-26.0 and 37.0-94.0 respectively. In this study, percentage of DIN was lower than 15% and dissolved organic nitrogen (DON) was higher than 80%. Mean of annual dissolved inorganic phosphorous (DIP) and organic phosphorous were 0.58± 0.04 and 0.48± 0.02 µM, respectively. DIP and DOP percentages recorded 54 and 46 respectively. Mean annual of dissolved silicon (DSi) obtained 9.5± 0.2 µM. Based on the results, the system was in phosphorus limitation during spring and summer but it shifted to nitrogen limitation in autuman and winter. Phytoplankton development was not limited by DSi at any seasons.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: 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/m3) and summer (94± 40 mg/m3) respectively. The results showed maximum abundance (553± 58 million cells/m3) and biomass (1209± 106 mg/m3) 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/m3, 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 recorde 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.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: This study was conducted to determine phosphorous and nitrogen species at the surface sediment in the southern Caspian Sea (Mazandaran Coast, Kelarabad). Surface sediments samples were collected at three stations from autumn of 2011 to winter of 2012. All samples were perpared by digesting and extracting processes and then phosphorous and nitrogen species concentrations determined using spectroscopy instrument. Results of this study showed that annual mean of Loosely-P, Fe-P, Al-P, Bioava.-P, Ca-P, TIP, Rese.-P and TP was obtained as 5.06±0.33, 55.11±2.52, 42.38±3.74, 102.52±5.68, 172.91±7.12, 275±9.12, 333.30±28.52 and 608±52 µg/g.dw, respectively. The results also showed that inorganic phophotous was less than organic phophorous during different seasons, however, mean percentage of residue-P containing organic compounds and non-degredable compounds was more than 50 percent. Percentage of Ca-P was higher than 60, whereas Bioava.-P was less than 40 percent. In addition, Fe-P and Loosely-P attained the maximum and minimum values, respectively, among the bioavailable phophorous. The order of different forms of phosphorous were recorded as Org-P〉Ca-P〉FeP〉Al-P〉Loosely-P. Annual mean of NH4/N, NO2/N, NO3/N, TIN, TON and TN were observed as 4.23±0.50, 0.06±0.01, 0.74±0.12, 5.02±0.53, 2.48±0.63 and 7.53±0.51 µg/g.dw, respectively. Annual percentage of TIN was two folds than TON and concentration of NH4/N was also four times than NO3/N. As a conclusion, the results revealed that main causes of Bioava.-P adsorbtion and desorbtion were temperature, Eh and pH. Also, the form of NH4+ /N was of a high percntage because of anaerobic condition in the sediments. According to the high ratios of nitrogen/phosphorous of sediments to nitrogen and phosphorous of bottow water, it finds that released of those from the sediments to water will be happned with high rates. Therefore, it is expected that the establishment of fish farming cages should be carried out with more precautionary approaches which not leads to increased algae bloom.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: Limnologicalstudyof SabalanrunoffDamfor aquaculturecold water fish was conducted in sixtimesat fourstationsfrom JulytoDecember2009.Averageminimumandmaximumparametersmeasuredindifferentstationswere included water temperature, dissolved Oxygen, total hardness, electrical conductivity, pH, BOD5, COD,TDS, NH4, NO2, NO3, PO4, TN, TP, SiO2, respectively (10/3 ± 9/5-14 ± 8/7° C), (9 ± 1/2-11/4 ±2/1 mg/liter), (367 ± 19/8-381 ± 17/8mg/liter), (0/95 ± 0/07-1/05 ± 0/07 mz/cm), (8/3 ± 0/1-8/4 ± 0/1), (3 / 3 ± 1/14-3/88 ± 0/71mg/ liter), (15/5 ± 3/1-16/3 ± 3 mg/liter), (0/48 ± 0/04-0/54 ± 0/06mg/ liter), (0/08 ± 0/02-0/13 ± 0/07 mg/liter), (0/004 ± 0/003- 0/05 ± 0/1 mg/ liter), (0/6 ± 0/2-0/64 ± 0/29 mg/ liter), (0/19 ± 0/07-0/22 ± 0/07 mg/ liter), (10/48 ± 0/6-10/98 ± 0/54mg/liter), (0/39 ± 0/11-0/44 ± 0/18 mg/liter), and(9/9 ±0/6-11/1 ± 1/4 mg/liter). Averageminimumandmaximumof water heavy metalswas included of Cd, Pb, Zn, Fe, Cuand Ni respectively was measured as ND(No Deliver), ND, ND- 0/242, ND- 1/075, ND- 0/018andND- 0/014inmg/ liter. Alsoamong the16organochlorinecompoundsmeasuredthehighestamount of was belonged totoxinHexachlorine Benzene (1/5 mg/ liter). The results of theanalysis ofwater quality parametersshowed that parametersexcept ofCOD, TDS, PO4, TP, Zn, Fe andwater temperature, otherparametersdo not haveany restrictions foraquaculturecold waterfishin therunoffDam. Based on data results it was noticed that there was temperature restriction up to November at downstream and station 2 showed less temperature fluctuation and more suitable condition compared to other stations. BOD5 value was within the allowable range for growing trout, in which station 2 somewhat with lower volatility of value had the most suitable BOD5 condition.In the present study, the amount of TDS in the study area was somewhat higher than the limitation and since TDS values increased with distance from the dam, therefore station 2 had somewhat better conditions for fish farming.In addition the amount of EC in the study area, indicating the inappropriateness of it for various activities in the fisheries.Although none of the stations in terms of the amount of phosphorus didn't show favorable conditions for rainbow trout fish propagation, it appears between the researches stations, station 2 had the most favorable terms.The results of this study (regardless of the unseen), it seems that in August and September; Zn had overestimated value for cold fish propagation. Recent study showed that among heavy metals, Fe in water, sediments and fish was over limitation value. Also, Fe value was measured of 1.08 at station 4, which showed over normal value for cold fish propagation. Therefore, station 2 at downstream seemed to have suitable cold fish propagation due to lower Fe value. On the based on the recent study, planktonic biological index did not endorse water quality for fish propagation. In this study, aquatic plant such as Potamogetonpectinatus and Pheragmitiesaustraliswas found at water of higher and somehow polluted organic matter. Probably, based on the results it was noticed that downstream water of dam was polluted to organic matter. At the recent study, resisted maroinvertebrates to organic matter (Chironomidae) was consisted noticeable frequency compared to other sensitive invertebrates to organic matter (EPT).Statistically, it can be expressed that probably organic pollution resulted to increase of resistance invertebrates and decreased of sensitive groups. In recent study, EPT/CHIR index was measured 0.6 in station 2 and 1.74 in station 4. This ration was less to many other mountain rivers. As ETP sensitive invertebrates has higher sensitive to other groups with the regards of environmental condition and pollution, unpredicted increase of Chironomidae compare to sensitive groups resulted of EPT/CHIR value which showed environmental stress. In this study, HFBI index was measured as 7.49 at station 2 and 7 in station4. Based on HFBI index, station 2 was classified as a high organic pollution and station 4 with noticeable organic pollution. At the recent study, station 2 was catch more fish to station4. For instance, Squaliuscephalus and Alburnoides bpinctatuswere catch in station 2 and were not found in station 4. As a whole, Biologicalindicators whichwas includedPlanktonBioindicator, EPT / CHIR. ,HilsenhoffBiologicalIndicator, diversityanddistribution ofaquaticplantsandfish, showed water situation inrunoffDamrich inorganic matter. Finally, thestudy areawasapprovedfor fish farmabout 50tons and needs managementarrangementswiththeincreasedproduction rate.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: In recent years the incidence of algal blooms caused by Nodularia to become one of the serious problems and is threated life of aquatic organisms in the southern Caspian Sea. Nodularia is a Blue-green algae (cyanobacteria group) and due to production of nodularin toxin is importance. In this study, the first, three species of Pseudomonas including aeruginosa, putida and fluorescens were isolated from Tajan river estuary and identified using biochemical tests and compared to standard species. The trend of Nodularia spumigena biomass (log 5) and pseudomonas species (log 7 and 8) were examined in 30 treatments for 10 days in aquarium scale. Parameters such as chlorophyll a, dissolved oxygen, phosphate and nitrate were tested at different time the same time. The results showed that the decline trend of nodularia in aeruginosa and mixed species treatments were better than other treatments and log 8 of bacterium was also more inhibitory effect than to log 7. Similar results were observed in double layer on agar medium and latter treatments had algaecide effect on nodularia. However, putida and fluorescens treatments had algaestatic properties. Concentration of chlorophyll a, dissolved oxygen and nitrate in all treatments, especially aeruginosa and mixed bacteria have been often decreased (p〈0.05). Changes of latter factors in control treatment have been relatively consistent. Although the phosphate changes at different time of relative decline, but nevertheless significant differences were observed. The parameters examined in this study were in direct contact with the algae population and decrease or increase of these factors cause significant change in algae biomass. The conclusion showed that different strains of pseudomonas are able to reduce the population of algae N. spumigena in aquarium scale and the results observed in combination treatment were better than other treatments. The challenge examination of pseudomonas and nodularia in mesocosm scale, evaluation of bacterial metabolites, and also quality and quantity analysis of chemical and biological factors involved in the process is recommended and with achieve reasonable results can be made from this indicator bacteria during algal bloom in the larger ecosystem.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: This study was conducted to determine the physico-chemical characteristics of water during four season and 8 transects (Astara, Anzali, Sefidroud, Tonekabon, Nowhshar, Babolsar, Amirabad, Bandar Tourkman) in the Southern of Caspian Sea in 2009-2010. 480 samples were collected at different water layers and then physicochemical parameters were measured based on standard methods. Result of this study showed that surface water temperature was varied from 7.2 to 29.8 ◦C in winter and summer, respectively. Minimum fluctuation of water temperature was observed at 100 m depth (6.8-10.3 ◦C). Mean value of water transparency was obtained 4.91±0.24 m. This value increased from inshore to offshore. pH value was fluctuated from 7.15 to 8.83 unit with variance of 1.54. Maximum DO concentration was observed at surface layer (8.40±0.08 mg/l) with 137±18 saturation and minimum was at 100 m depth (6.46±0.18) with 86.1±2.8 saturation. The nitrite, nitrate and ammonium concentration were ranged 0.0-0.2, 0.0-4.6 and 0.05-7.12 µM, respectively. Maximum value of TN was observed at inshore and minimum at offshore (100m). Nitrite concentration decreased from inshore to offshore but increased from surface to the bottom (100 m). The inorganic phosphorous increased at surface water and also at the bottom. Trend of inorganic and TP was similar. Minimum of N/P ratio were observed at summer (5.48±0.38) and maximum value at winter (9.13±0.46). This value of N/P ratio showed that the growth of phytoplankton was limited by nitrogen. The dissolved silicate was decreased from spring (230.7±6.65 µg/l) to winter.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: Recently, the ecology of the Caspian Sea coastal has undergone with increasing development of human activities and industrial wastewater discharge. Therefore, considering the current situation, evaluate of pollutants issue in the Caspian Sea is very important. Results of this study showed that levels of heavy metals (Cd, Cr, Cu, Fe, Pb, and Zn) of water had lower than standard and also acceptable for aquatic life. Significant accumulation of metals such as Co, Cu and Cr in the sediment was observed at transect Sefidrood and Anzali in comparison with six other transects (Turkmen, Amirabad, Babolsar, Noshar, Tonekabon and Astara) and for Ni at transects Sefidrood and Astara compared with six other transects (Turkmen, Amirabad, Babolsar, Noshahr, Tonekabon and Anzali) (P〈0.05). The amount of Zn in fish muscle Liza saliens was maximum and then metals such as Fe, Cu, Pb, Cd, Ni, Hg and Co were recorded (P〈0.05). In the north of Iran, two kind of bony fish, such as R..frisii kutum and Liza.s have maximum catchments as compared with other bony fish in the Caspian Sea. Based on calculation of risk of Target Hazard Quotient (THQ), we obtained THQ was less than one for all metals in young and adults human. Thus, consumption of R..frisii kutum and Liza.s per capita with 6 kg will not be at the risk for young and adults. Among of oil derivatives, polyaromatic hydrocarbon (PAHs) is hazardous compounds in the environment. Environmental Protection Agency (EPA) was announced 16 compositions of PAHs as an index. The results of this project showed that concentration of two and three rings of PAHs was lower than 4, 5 and 6 rings of water, sediment and fish at most stations and seasons. Among of 16 PAHs, only Benz(α)anthracene, chrysene, Benzo(α)pyrene and Dibenz (α, h)anthracene compounds were contained with ecological risks (HQ) more than one in the water and sediment. In addition, three compounds such as Chrysene, Benz(α)anthracene and Benzo(α)pyrene were observed in the edible fish tissues (Liza.s and R..frisii kutum) which have high ecological risks in the water and sediment. During four seasons (spring, summer, fall and winter), maximum concentration of organochlorine residue in the surface water (5m depth) were belong to β-Endosulfan (Turkmen), Dieldrin (Babolsar, Tonekabon) and endosulfan sulfate (Astara) and at 10m depth were γ-BHC, Dieldrin compounds (Tonekabon), DDT (Turkmen) and Aldrin (Babolsar). This values at 50m depth were belong to γ-BHC (Anzali), δ-BHC (Tonekabon), Dieldrin (Amirabad), and heptachlor (Amirabad). Maximum percentage of organochlorine pesticides residue in the sediments was belonging to only Aldrin compound at stations Turkmen, Babolsar and Tonekabon. In addition, maximum concentration organochlorine pesticides residue in fish tissue (Liza.s and R..frisii kutum) was DDT and Endrin aldehyde compounds. Mean surfactant concentration (LAS) of surface water (5, 10 and 50 m depths) at eight transects was 0.017±0.049 mg/l. The maximum concentration of LAS were 0.084 mg/l and 0.082 mg/l in spring and summer (Anzali transect), respectively. This value was 0.035 mg/l and 0.060 mg/l in autumn and winter (Sefidrood transect), respectively. As a conclusion, the concentration of surfactant in the Caspian Sea basin is not critical as compared with standard level.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: The water quality provides the valuable information about the available resources for human usage.The reservoirs are the important resources of surface water which could be considered as an appropriate water resource for irrigation, drinking water and also fish culturing. The Shahid Rajaei Reservoir- Sari is an important reservoir in Iran, which conducted to study on its water quality in this survey. In this study, some of the physicochemical parameters and Chlorophyl- a of Shahid Rajaei reservoir were measured at 4 stations (Shirin Roud branch, Sefid Roud branch, the crossing point of branches, near the tower) during six sampling months (June, July, August, September, November and February) in 2012-2013. The water quality and trophic status of reservoir calculated based on some reference values and the modified Carlson formula. The results showed that the mean (±Standard Error) of temperature, dissolved oxygen, pH, phosohate, amonium and nitrate concentrations and Chlorophyl a were 21.35 (±1.30) ºC, 10.48 (±0.37), 8.54 (±0.04), 0.050 (±0.004), 0.036 (±0.004), 0.75 (±0.03) mg/l and 18.00 (±7.23) mg/m3 , respectively. In the present study, temperature between surface and deep layer was stratified in June and July, which the stratification was registerd 0.47 and 0.69 °C decreases with increasing of each meter depth in 15 to 30 meter culumn. But, these changes for each increasing meter of water depth were 0.2 to 0.26 °C in August and September, respectively, and finally was close to zero in November. In the warm months (July, August and September) with the formation of thermal stratification in the reservoir was formed oxygen stratification, but in the cold season (November and February), with vertical mixing of water oxygen and percent saturation of the reservoir was nearly homogeneous. The results showed that the European authorities (OECD) trophic status varied between mezotrophic to hypertrophic during the sampling period at all stations. The comparison with the values listed in the references of Iranian dams based on transparency and chlorophyll variables showed similar results. However, phosphorus variable (due to limited for phytoplankton) was not showing the true conditions of trophic status. As a conlusion, trophic status of Shahid Rajaei dam based on Carlson trophic index (TSI) was obtained oligotrophic (May and October), mezotrophic (February) and eutrophic (August and September) condintion during diferent months. Therefore, water management of the reservoir was more attention during warm months.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: This study was conducted to physico-chemical characteristics of water in the Iranian coastal of southern Caspian Sea during four seasons at 8 transects (Astra, Anzali, Sefidrud, Tonekabon, Nowshahr, Babolsar, Amirabad and Bandar Turkman) during 2009-2010. 480 samples were collected at different layers of water and then analyzed based on standard methods. Results showed that the mean of water temperature were 18.67±0.32 and 17.82±0.43 ◦C at the surface and euphotic layer, respectively. Minimum and maximum of water temperature were recorded in winter (6.40) and summertime (27.60). In addition, temperature gradient was ranged between 12 to 15 ◦C at 20 to 50 layers in 50 and 100m depths. Mean of salinity was 11.04±0.17 g/l at euphotic layer. Pearson correlation between temperature and salinity was positively significant. Therefore, maximum salinity was recorded in summer and minimum in winter. Mean of transparency (SD) in the present study was 4.35±0.21 m which compared to the pervious sampling period (2008) showed small decrease, but the mean of pH was observed 8.43±0.01 which was higher than the previous sampling period (2008). The mean of DO and DO% were observed 5.72±0.06 ml/l and 130±1 percent at euphotic layer during sampling period. The mean of DO% was recorded 104±5 at euphotic layer in 1996 (before introduction of Mnemeiopsis leidyi), but the study in the years 2004, 2008 and present (one decade after introduction of Mnemeiopsis leidyi) this value was registered higher than 120% at euphotic layer. This shows that trophic status of Caspian ecosystem shifted from oligotrophy (before introduction of Mnemeiopsis leidyi) to meso-eutrophy (after introduction of Mnemeiopsis leidyi). Annual concentration of inorganic nitrogen (DIN= NH4 +, NO2-, NO3-) has a fairly wide variation. Percentage of nitrogen components out of DIN were varied 9-98, 0.2-28.2 and 0.0-90.0 respectively. In this study, percentage of DIN was lower than 15% and organic nitrogen (DON) was higher than 80%. Overall, results showed that water temperature, salinity, transparency and DON were recorded lower than the previous study (2008), but DO, DO%, pH, NH4+, NO3- and DSi were higher than the previous sampling period. Inorganic phosphorous (DIP) and NO2- have not changed substantially. N/P ratio of Caspian Sea has a narrow range which order of magnificent lower than other seas. The results of the present study showed that Caspian ecosystem was nitrogen limitation before introduction of Mnemeiopsis leidyi, while it seems that after introduction of Mnemeiopsis leidyi the system has been shifted to the phosphorous limitation.

Description: Iranian Fisheries Science Research Institute

Description: Published

Description: Abnormal algal bloom is a global issue. So the Caspian Sea such as the other aquatic environment is at risk of algal bloom. Thus the present study in 2013-14, was conducted to get goals, firstly determination of temporal and spatial variation of phytoplankton abundance and biomass with emphasis on dominant species with bloom potential and secondly detemination of chlorophyll-a concentration. Mostly sampling conducted in mid-seasons in 4 transects (Anzali, Tonkabon, Nowshahr and Amirabad) at surface, 10 and 20m layers in depths of 5, 10 and 20m. Based on the results the annual mean±SE of phytoplankton abundance was 219 ± 33 million cells/m3. The minimum and maximum valus of abundance recorded in summer (73 ± 31 million cells/m3) and winter (505 ± 55 million cells/m3) respectively. Totally 147 phytoplankton species identified which classified in 7 phyla and small phytoflagellates group. The major portion of abundance formed by Bacillariophta (81%). The minimum and maximum seasonal phytoplankton biomass were in summer (90 ± 20 mg/m3) and winter (1777 ± 201mg/m3) respectively. The annual median of chlorophyll-a concentration was 2.43 mg/m3 at surface layer and its seasonal value in spring, summer, fall and winter recorded 1.54, 1.18, 5.81 and 2.59 mg/m3 respectively. Therefore algal blooms started in fall and it was followed with lower intensity in winter. Mean of phytoplankton abundance and biomass in winter were 3-6 folds to other seasond. But chlorophyll-a concentration in winter was low and closed to the values in spring and summer. Probably, decreasing of ligh availibity and low chlorophl content of dominant species showed important roles in decreasing of chlorophyll-a concentration in winter. As conclusion, the abundance of Stephanodiscus socialis, Binuclearia lauterbornii and Thalassionema nitzschioides classified in the fair level of bloom (100-1000 cells/ml) in spring (in Anzali transect), summer and fall (in Amirabad transect) respectively. In winter, Dactyliosolen fragilissima،(in all transect except Nowshahr) and Pseudonitzschia seriata were in this group. The presence of Thalassionema nitzschioides (as valuble food in food chain) in dominant species list (same patern to the stability year of Caspian Sea) and decreasing of percent abundance of harmful species from 68% (in 2008-2009) to 43% (in this study) are good signs of water quality from Caspian Sea. On the other hand, Pseudonitzschia seriata as a harmful alga (ability to produce toxin and bloom forming) has important role in environmental issues. In current study, Pseudonitzschia seriata expanded from cold season to other seasons (even in summer). Also, it had high percent frequency (100%) and abundance (294 ± 30 million cells/m3) in winter which indicate to unsuitable condition of water quality in Caspian Sea.

Description: Iranian Fisheries Science Research Institute

Description: Published