Recursos de colección

Aquatic Commons (41.069 recursos)

The Aquatic Commons is a thematic digital repository covering the natural marine, estuarine /brackish and fresh water environments . It includes all aspects of the science, technology, management and conservation of these environments, their organisms and resources, and the economic, sociological and legal aspects.

Subject = Limnology

Mostrando recursos 1 - 20 de 34

  1. Phytoplankton of Aras dam reservoir (Iran): an attempt to assess water quality

    Mohebbi, F.; Riahi, H.; Sheidaei, M.; Shariatmadari, Z.
    The Aras reservoir, located in the north-west of Iran, plays an important role in fisheries, drinking and agricultural water supplies and recreational activities in the region. This study was performed to characterize the seasonal fluctuations of phytoplankton communities and their relationship with environmental factors in the Aras reservoir from August 2013 to May 2014. Sampling was carried out seasonally from 5 sampling locations. In each location three samples were taken for phytoplankton identification and enumeration, chemical analysis and chlorophyll a determination. In total, 72 species belonging to 5 divisions were determined. Cyanobacteria contained the highest density (74%) during the study...

  2. The effects of physicochemical parameters on fish distribution in Eğirdir Lake, Turkey

    Yağcı, A.; Apaydın Yağcı, M.; Bilgin, F.; Erbatur, İ.
    The present study was conducted based on the fish species and physicochemical parameters of Eğirdir Lake. Sampling was carried out monthly from January through December 2010 between 9 am and 11 am. The parameters measured were water temperature, depth, secchi disk depth, turbidity, dissolved oxygen, saturation of dissolved oxygen, pH, conductivity, chloride, hardness, calcium, magnesium, bicarbonate, carbonate, nitrate, nitrite, ammonium, sulphate, phosphate, silica, organic substance, acid power (SBV) and chlorophyll-a. Monthly sampling was performed at four stations at different depths. Water temperature ranged from 6.9±0.5 °C in February to 26.8±0.4 °C in August. Minimum secchi disk depth recorded was 0.5...

  3. Quantification of individual phosphorus forms in surface sediments of the Southern Caspian Sea - Iranian Coast: A sequential extraction procedure

    Niyazi, L.; Chaichi, M.J.; Nasrollahzadeh Saravi, H.; Najafpour, S.
    Seventy-two sediments from four stations (Anzali, Tonekabon, Noshahr and Amirabad), located in Caspian Sea-Iranian coast were examined on the basis of P-fractionation in autumn and winter of 2013-2014. Several forms of the phosphorus in sediment were separated and extracted according to sequential extraction method. Then the extracted phosphorus in each fraction was determined by UV–Vis spectrophotometry. In addition, total concentrations of Ca, Fe and Al in sediment fractions were also measured by atomic absorption spectroscopy. In autumn the rank order of P-fractions was: Ca-P>Residual-P>BD-P>Al-P>loosely-P and in winter it was: Ca-P>BD-P>Residual-P>Al-P>loosely adsorbed-P. In both season the loosely adsorbed phosphorus (NH4Cl–P) represented...

  4. The relationships between chlorophyll-a dynamics and certain physical and chemical variables in the temperate eutrophic Çaygören Reservoir, Turkey

    Çelik, K.
    The Çaygören Reservoir was sampled monthly from February 2007 to January 2009 at three stations to determine the relationships between the chlorophyll-a (Chl-a) dynamics and soluble reactive phosphorus (SRP), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), water discharge, water transparency, water temperature (T), specific conductance (SC) and pH. Thermal stratification occurred in the reservoir from May to September. The maximum chlorophyll-a concentrations were measured (using a YSI multi probe) in the fall and the minimum concentrations were recorded in the winter. Differences in the concentrations of chl-a , SRP and NO3-N were significant among seasons (p<0.01), but not among sampling stations (p>0.01). The...

  5. The pattern determination of sea surface temperature distribution and chlorophyll a in the southern Caspian Sea using SOM model

    Bahmanzadegan, A.R.; Lari, K.; Fatemi, M.R.; Azarsina, F.
    Remote sensing has changed modern oceanography by proving synoptic periodic data which can be processed. Since the satellite data are usually too much and nonlinear, in most cases, it is difficult to distinguish the patterns from these images. In fact, SOM (Self-Organizing Maps) model is a type of ANN (Artificial Neural Network) that has the ability to distinguish the efficient patterns from the vast complex of satellite data. In this study, the sea surface temperature data and chlorophyll a related to a part of south Caspian Sea were investigated weekly by NOAA satellite for three years (2003–2005) and the annual...

  6. Plankton communities of Ikpa River, South East Nigeria exposed to sand-dredging activities

    Ekwu, A.O.; Udo, N.D.
    Plankton communities of Ikpa River, downstream from a sand-dredging area were studied for a period of i2 months (March 2010 to Febntary 2011), covering dry and wet seasons. Most Physico-chemical parameters (pH, Turbidity, Silicates, Transparency and Conductivity) exhibited highly significant spatial variation (p<0.01), whereas seasonal variation of these variables was not statistically significant(p>0.05). Significant seasonal variation (p<0.05) was however observed in temperature, Dissolved Oxygen, Biochemical Dem and(BOD), total Dissolved Solids (TDS), Phosphorus, Nitrates and Conductivity. A total of 51 Taxa of Phytoplankton to 43 genera and 5 families were identified during the period of study. Bacillariophyceae recorded the highest relative...

  7. Survey of physical characteristics of the upper reaches of new Calabar River, Niger Delta, Nigeria

    Uzukwu, P.U.; Leton, T.C.; Jamabo, N.A.
    One of the priority research projects of the Nigerian Institute for Oceanography and Marine Research (NIOMR) is broodstock development and mass propagation of silver catfish, Chrysichthys nigrodigitatus of which the broodstock is naturally abundant in New Gala River. Selected physical characteristics and water physico-chemical parameters of the upper reach of the New Calabar River at Aluu were investigated. The highest depth value of 9.20 m was recorded in the middle of the river. The width of the river measured during spring high tide and low tide were 174 m and 110 m respectively. The cross-sectional area and average flow velocity...

  8. Assessment of chemical and nutrient characteristics of selected wetland waters and sediments in Bo - Moyamba districts, southern Sierra Leone

    Olapade, O.J.; Tarawallie, S.
    The impact of anthropogenic activities on chemical and nutrient characteristics of selected wetlands in Moyamba and Bo districts was investigated. Water and sediments samples for nutrient and trace metal analysis were collected for two seasons (wet and dry) at sampling sites. Anthropogenic activities such as industrial effuent, domestic and agricultural waste disposal constitute major sources of wetland pollution in the selected districts. Samples of water and soil were analyzed for metals (Cr, Co, Cd, Ni, Pb, Mg, Mn, Fe, C1 and Zn) and nutrients (Ca, K, P and Na) levels were determined and their seasonal variations were compared at (p>0.05)...

  9. Gross alpha and beta surveys of Lake Kainji water

    Adamu, R.; Abubakar, A.K.; Vatsa, A.M.; Zakari, Y.I.; Ahmed, Y.; Rafindadi, I.Z.
    A gross alpha and beta survey of the water of Kainji Lake was conducted using multi-channel analyzer, a proportional counter detector. This was done to estimate the gross radioactivity concentrations due to natural radionuclides in the lake water. Radioactivity, a phenomenon that leads to production of radiations, and radiation is known to trigger or induce cancer. The gross alpha and beta activity concentration analyzed in the water shows that the alpha activity ranges from 1.0 x 105 Bq/cm3 to 0.7Bq/cm3 with an average value indication of 0.0702Bq/cm3, whereas the beta activity concentration indicated BDL for all the sites with exception...

  10. Changing trends in the abundance and biomass of cyanobacteria in the southern part of the Caspian Sea in 2009 (the stretch between Tonekabon and Amirabad)

    Mahdavi, M.; Maktabi, T.; Mahdavi, S.; Roostaie, M.; Alasvandi, M.F.
    Changes in abundance and biomass of cyanobacteria have been studied in the southern part of the Caspian Sea (the stretch between Tonekabon and Amirabad) in four seasons (spring, summer, autumn, winter) in which samples were taken from five depths of 5, 10, 20, 50 and 100 meters in the stations of Tonekabon, Noushahr, Babolsar and Amirabad. Samples were fixed in formalin (2-2.5%) before transferring to the lab for both qualitative and quantitative analyses. Ten species of cyanobacteria were identified with higher abundance and biomass in the euphotic layer compared to the aphotic layer. Temperature and nutrients have shown significant differences...

  11. Isolation and identification of halophilic bacteria from Urmia Lake in Iran

    Irannejad, S.; Akhavan Sepahi, A.; Amoozegar, M.A.; Tukmechi, A.; Motallebi Moghanjoghi, A.A.
    Halophiles are in all three domains of life: Archaea, Bacteria and Eucarya. Halophilic microorganisms in addition to forming a major part of life biodiversity can have many biotechnological applications. The objective of this research is isolation and identification of halophilic bacteria from Urmia Lake in Iran and the study of its bacterial biodiversity. After sampling of brines from Urmia Lake from 10 stations and depth of approximately 30-50 cm, in April 2011 and transfer to the laboratory in the sterile conditions, samples were enriched and cultured on defined media, and incubated. After appearance of colonies, selected strains were studied based...

  12. Trace metals in water, fish and sediments from Elechi Creek, Port Harcourt, River State, Nigeria

    Vincent-Akpu, I.F.; Mmom, T.C.
    The concentration of trace metals: Cadmium (Cd), Lead (Pb), magnesium (Mn), Nickel (Ni) and Zinc (Zn) were determined in water, sediment and fish tissues (S. melanotheron) collected from Elechi creek in Port Harcourt, Nigeria between October and November, 2010. The overall mean concentrations of the trace metals (Mg/g dry weight) in all combined samples ranged from 0.06-0.24 (Cd), 0.59-2.39 (Pb), 0.08-1.15 (Mn), 0.15-0.48 (Ni) and 0.18-7.04 (Zn) respectively. The concentration of the trace metals in water, fish and sediments were in the following order: Pb >Ni >Zn>Cd >Mn; Zn>Pb >Mn>Ni >Cd and Zn> Pb>Mn>Ni>Cd respectively. Except in water, Zinc had...

  13. Influence of physico-chemical parameters on the distribution of freshwater snails in River Uke, Nassarawa State, Nigeria

    Obande, R.A.; Dauda, K.P.; Adah, P.M.
    The Physio-Chemical parameters of River Uke, Keffi, Nasarawa State, were studied between the months of February to August 2011. Nine water parameters were analyzed and Melanoides tuberculata was also identified using identification keys by Brown and Kristensen (1993). These include temperature, pH, alkalinity, turbidity, conductivity, nitrates, phosphates, total dissolved substances and dissolved oxygen using the methods described by Boyd (1979). The temperature ranged between 25~'C - 27.5~'C (mean = ~c 26.31~'C), while pH ranges between 6.3 and 7.5(mean = ~c 6.89). The highest value obtained for alkalinity was I5.4mg L-1, while the lowest was 4mgL-1(mean = ~c 10.2mg L-1). Dissolved...

  14. Design of pumping station for a tidal fish farm in Niger Delta, Nigeria

    Uzukwu, P.U.; Leton, T.G.
    The design of pumping station for submersible FLYGT pump 3102 version LL to redress the water supply problem of some ponds in the tidal fish farm of African Regional Aquaculture Centre (ARAC) located in Omuihuechi, Aluu, Rivers State, Nigeria was carried out. Prior to the design baseline study was carried out for the proper sitting of the pumping station. The topographic survey of the area indicated gentle sloping woodland, with the highest and lowest elevations of 11.00 m and 1.00 m respectively. The mean peak heights of water in the supply canal during spring and neap tides ranged from 0.95...

  15. The relationships between chlorophyll-a dynamics, certain physical and chemical variables in the temperate eutrophic Çaygören Reservoir, Turkey

    Çelik, Kemal
    The Çaygören Reservoir was sampled monthly from February 2007 to January 2009 at three stations to determine the relationships between the chlorophyll-a (Chl-a) dynamics and soluble reactive phosphorus (SRP), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), water discharge, water transparency, water temperature (T), specific conductance (SC) and pH. Thermal stratification occurred in the reservoir from May to September. The maximum chlorophyll-a concentrations were measured (using a YSI multi probe) in the fall and the minimum, SRP and NO3-N were significant among seasons (P<0.01), but not among sampling stations (p>0.01). The differences in the Secchi disk transparency were significant both among sampling stations and...

  16. Microbiological index of water pollution in Lake Kivu, Rwanda

    Olapade, O.J.; Omitoyin, B.O.
    Investigation of the microbiological purity of Lake Kivu as index of water pollution was carried out in Gisenyi, Kibuye and Cyangugu over a period of 24 months. Microbial load did not differ significantly with season and locations but Fecal Coliform (FC) had positive significant correlation (r = 0.36; p<0.05) with season. Mean Total Coliform (TC) (cfu/100ml) was highest 7.7 x 105 in Gisenyi and lowest 1.7 x 105 at Cyangugu. These values exceeded the 5000 colony forming units/100ml recommended by WHO for public surface water supplies. Total heterotrophic bacterial (THB), FC, TC and Fecal streptococcus (FS) were widespread with abnormally...

  17. Limnological studies of Bosso dam and it's tributaries in Minna, Niger State, Nigeria

    Yakubu, U.P.; Ndakatu, M.A.; Yusuf, M.K.
    The physico-chemical parameters of Bosso Dam were analyzed weekly for a period of six (6) weeks from 29th October, 2009. In all, six (6) stations were identified within the dam. The physico-chemical parameters assessed were: temperature, dissolved oxygen, pH, alkalinity, hardness, conductivity and transparency. The results obtained from the analysis revealed slight variations in most parameters. There was no significant difference p>0.05 in pH regardless of stations and weeks. But significant difference p>0.05 were observed in dissolved oxygen, nitrate, temperature, conductivity, hardness, alkalinity, biological oxygen demand, transparency, in respect regard to stations. These variations could be due to influx of...

  18. Preliminary studies on the phytoremediation potential of Phragmites karka in Asa river

    Uka, U.N.; Mohammed, H.A.; Aina, E.
    The ability of Phragmites karka to absorb and translocate the heavy metals Zinc,Copper,Cadmium and lead was investigated in Asa river, Ilorin Southwest Nigeria.The results of the translocation ability were in the order Cu>Zn>Cd and Pb. The bioconcentration factor for Zn,Cu,Cd and Pb in the root, stem and leaf had low values. Heavy metal accumulation in the roots were greater than those of the shoots. The quantities of accumulation in the roots were in the order Zn>Cu>Pb>Cd. This study suggests that Phragmite karka is less suitable for sequestering of these studied heavy metals.

  19. Spatial and temporal variations of physicochemical variables in a small 'pristine' stream in Niger Delta, Nigeria

    Sikoki, F.D.; Anyanwu, I.N.
    Spatial and temporal variations of physico-chemical variables of Onu-Iyi ?Ukwu stream were studied for 12 months from March 2005 to February 2006. Three sampling stations were established along the main stream channel from source to mouth. Spatial variation in physico-chemical parameters indicated that total alkalinity, total hardness, conductivity, and nitrate-nitrogen (NO3) recorded their highest values at the upper reaches (with values 14.0mg/l, 88.09mg/l, 17.00~kscmiscm, and 0.60mg/l respectively). Dissolved Oxygen (DO) and pH had their maximum values of 8.20mg/l and 6.94 at the middle reaches. Turbidity, biochemical oxygen demand (BOD), temperature and phosphate-phosphorus (PO4) increased steadily from source to mouth. The...

  20. Comparative analysis of physicochemical characteristics of ABU and Zaria Dam

    Yunusa, A.; Bolorunduro, P.I.; Onimisi, H.U.; Misau, A.B.; Ahmed, A.
    The physical and chemical parameters of ABU Dam and Zaria Dam were carried out between September and October 2009. The results obtained in the two water bodies were temperature 27.7 0C, pH (7.5 and 7.3), dissolved oxygen (5.8 mg/l and 5.0 mg/l), biochemical oxygen demand (1.74 mg/l and 2. 16 mg/l), alkalinity (58 mg CaC03/l and 49 mgCaCO3/l) P04-P (2.47 mg/l and 1.59 mg/l) NO3-N (3.67 mg/l and 3.47 mg/l), conductivity (54.70 ~ks-1 and 42.48 ~ks-1), total hydrocarbon (TH) (47.66 mg/l) and 48.00 mg/l) and total dissolved solids (32.68 mg/l and 25.35 mg/l) respectively. There was no significant difference in...

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