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    Dissolved heavy metals in the Tigris River (Turkey): spatial and temporal variations
    (Springer Heidelberg, 2013) Varol, Memet; Gokot, Bulent; Bekleyen, Aysel
    Multivariate statistical techniques, such as analysis of variance, cluster analysis (CA), correlation analysis, principal component analysis (PCA), and factor analysis (FA), were applied to determine the spatial and temporal variations of dissolved heavy metals in the Tigris River at 7 different sites spread over the river stretch of about 500 km during the period of February 2008 to January 2009. The results indicated that Fe, Cr, and Ni were the most abundant elements in the river water, whereas Cd and As were the less abundant. Cu, Fe, Ni, and Zn showed significant spatial variations, reflecting the influence of anthropogenic activities. The lowest total concentration of heavy metals was found at site 2 downstream of the Dicle Dam due to clean water from the dam. The concentrations of most metals were found lower when compared with results of previous studies due to reduction of the activity of the copper mine plant and the construction of two dams on the river. The lowest total concentrations were determined in February due to high precipitation and snow melts. Hierarchical agglomerative CA classified all the sampling sites into three main groups of spatial similarities. Clusters 1 (Maden and Bismil), 2 (Cizre), and 3 (Egil, DiyarbakA +/- r, Batman, and Hasankeyf) corresponded to moderate polluted and relatively low polluted regions, respectively. PCA/FA, CA, and correlation analysis suggest that Cu, Ni, and Zn are controlled by anthropogenic sources.
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    First Record of the Genus Phyllodiaptomus Kiefer (Copepoda, Calanoida, Diaptomidae) from Turkey
    (Central Fisheries Research Inst, 2017) Bekleyen, Aysel; Gokot, Bulent; Varol, Memet
    The genus Phyllodiaptomus Kiefer, 1936 is reported from Turkey for the first time. Phyllodiaptomus sp. collected from the Batman Dam Reservoir in Southeastern Turkey was observed only between May and November 2008. The female and male specimens are illustrated in detail. Phyllodiaptomus sp. is closely related to P. blanci (Guerne & Richard) and P. irakiensis Khalaf, from which it differs in several characteristics that are discussed. The present new record extends the known distribution of the genus Phyllodiaptomus to Turkey being a natural bridge between Europe and Asia.
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    First Record of the Order Choanoflagellida in Turkey
    (Central Fisheries Research Inst, 2011) Varol, Memet; Bekleyen, Aysel; Sen, Bulent; Gokot, Bulent
    We report the first record of the order Choanoflagellida in the waters of Turkey. The choanoflagellate Salpingoeca amphoridium James-Clark was found in plankton net samples in November and December 2008, and January 2009 from the Batman Dam Lake, the Batman Stream and Hasankeyf sampling site of the Tigris River. Salpingoeca amphoridium was found attached to planktonic diatom Aulacoseria granulata (Ehrenberg) Simonsen.
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    Geochemistry of the Tigris River basin, Turkey: Spatial and seasonal variations of major ion compositions and their controlling factors
    (Pergamon-Elsevier Science Ltd, 2013) Varol, Memet; Gokot, Bulent; Bekleyen, Aysel; Sen, Bulent
    A total of 204 water samples were collected from 17 sites in four different water bodies in the Tigris River basin during the period from February 2008 to January 2009. Major ions (Ca2+, Mg2+, Na+, K+, HCO3-, SO42-, Cl-, NO3- and SiO2), water temperature, pH, EC and TDS were determined, and consequently analysis of variance, correlation analysis, cluster analysis, factor analysis and principal component analysis were performed to explore their spatial and seasonal variations, quantify the geochemical and anthropogenic processes and identify factors influencing the ionic concentrations. The results indicated that waters in the Tigris River basin are mildly alkaline with high concentrations of Ca2+ and HCO3-, which in total account for approximately 78% of the total ionic budgets. All parameters studied in the Tigris River showed significant spatial variations, while EC, TDS, Cl-, SO42-, Na+, Ca2+, Mg2+ and HCO3- had significant spatial variations in the dam reservoirs. In the Tigris River, EC, TDS, SiO2, Ca2+ and Mg2+ displayed higher values in months of the dry season, while higher values for pH, NO3-, Cl-, SO42-, Na+, K+ and HCO3- in months of the wet season. In the dam reservoirs, all parameters studied except pH showed higher values in months of the wet season. The major ion chemistry of Tigris River basin is mainly controlled by rock weathering with HCO3- and Ca2+ dominating the major ion composition because of the abundance of carbonate rocks in the basin. A comparison with WHO standards for drinking water indicates that the basin has high-water quality. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.
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    A new record of the freshwater jellyfish Craspeducusta sowerbii Lankester, 1880 (Hydrozoa) in Southeastern Anatolia (Turkey)
    (Science Press, 2011) Bekleyen, Aysel; Varol, Memet; Gokot, Bulent
    We report the first record of the invasive freshwater jellyfish Craspedacusta sowerbii Lankester in Kralkizi Dam Lake, Southeastern Anatolia, Turkey. The medusa was found only in August, 2008 when average surface water temperatures were 26.9 degrees C.
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    Spatial and temporal variations in surface water quality of the dam reservoirs in the Tigris River basin, Turkey
    (Elsevier, 2012) Varol, Memet; Gokot, Bulent; Bekleyen, Aysel; Sen, Bulent
    Multivariate statistical techniques, such as cluster analysis (CA), principal component analysis (PCA), factor analysis (FA) and discriminant analysis (DA), were applied to evaluate the temporal/spatial variations of water quality data sets for Kralkizi, Dicle and Batman dam reservoirs in the Tigris River basin, obtained during 1 year (2008-2009) of monitoring. This study highlights the usefulness of multivariate statistical techniques for the evaluation and interpretation of complex water quality data sets, apportionment of pollution sources/factors and the design of a monitoring network for the effective management of water resources. Hierarchical CA grouped 12 months into two clusters (wet and dry seasons) and classified ten monitoring sites into four clusters based on similarities in the water quality characteristics. PCA/FA identified five factors in the data structure that explained 80% of the total variance of the data set. The PCA/FA grouped the selected parameters according to common features to help evaluate the influence of each group on the overall variation in water quality. Discriminant analysis showed better results for data reduction and pattern recognition during both spatial and temporal analysis. Temporal DA revealed nine parameters (water temperature, dissolved oxygen, total alkalinity, total hardness, nitrate nitrogen, ammonia nitrogen, total phosphorus, chloride and calcium), affording 100% correct assignations. Spatial DA revealed eight parameters (water temperature, pH, dissolved oxygen, electrical conductivity, nitrate nitrogen, orthophosphate phosphorus, sodium and total suspended solids), affording 92.5% correct assignations. Therefore, DA allowed a reduction in the dimensionality of the large data set and indicated a few significant parameters responsible for large variations in water quality that could reduce the number of sampling parameters. (C) 2011 Elsevier B.V. All rights reserved.