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    Relative variation of ionic composition in a karstic lake under the theory of unweighted vs weighted logratio analysis
    (Iwa Publishing, 2008) Cankaya, Emel; Sivaci, E. Ridvan; Kilinc, Sabri; Dere, Sueran
    The use of logratio analysis in limnological studies has proved to be effective for solving the problems of the constrained nature of compositional data. The method offers a graphical tool, the relative variation biplot, to explore relative changes of the ions. However, recent methodological developments have shown that the results can be perturbed by low-valued ions with high variances and proposed downweighting their influences as in correspondence analysis. Additional to all properties of the unweighted version, this weighted logratio analysis extends the previous work and has the advantage of the principle of distributional equivalence. As a motivating application, we chose a karstic lake with dominating ions calcium and sulphate causing other ions to be present relatively in low absolute levels. Besides, one of the collected compositional samples was suspected to be unusual which, in part, contributes to high relative variances. This paper is therefore concerned with the choice of the best method for the analysis of such extremely saline water systems by comparing performances of both unweighted and weighted logratio analyses. We concluded that introducing weights captured more features of ionic relationships with almost all compositional variability explained. We observed that the ratio of calcium to sulphate, ammonium or phosphorus (to a lesser extent) was particularly valuable in understanding the natural chemical process of the lake. A constant log-contrast model based on calcium, ammonium, nitrate and total soluble phosphorus appeared as an equilibrium equation.
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    Seasonal assessment of epiphytic diatom distribution and diversity in relation to environmental factors in a karstic lake (Central Turkey)
    (Gebruder Borntraeger, 2008) Sivaci, E. Ridvan; Cankaya, Emel; Kilinc, Sabri; Dere, Suekran
    Seasonal variation in the composition and concentration of epiphytic diatoms from a Karstic Lake, Great Lota, in Anatolia which has a distinctive ionic character was investigated during October 2000 and October 2001. A total of 66 diatom taxa belonging to 24 genera were identified. Mastogloia was the most dominant genus in all sampling periods. Gomphonema, Cymbella and Nitzschia were the subdominant epiphytic diatom genera. Relationships between epiphytic diatom assemblages and measured limnological variables were extracted by means of Redundancy Analysis (RDA). It was revealed that temperature, calcium (Ca2+), sulphate (SO42-) and total soluble phosphate (TSP) parameters accounted for a significant amount of the variation in the distribution of the diatom assemblages. While some dominant taxa (e.g. Mastogloia smithii and Nitzschia amphibia) appeared relatively abundant in the cold waters with high calcium concentration, other taxa (e.g. Rhopalodia gibberula and Cymbella affinis) showed affinities towards warmer water with low calcium level. Cluster analysis produced four major groups reflecting the importance of seasonal influence on the epiphytic taxa. Formation of these seasonal clusters was controlled mainly by the increase and decrease of Mastogloia species. Influence of seasons on species compositions was also assessed in terms of Diversity index (H') and evenness (J) values.
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    Öğe
    Seasonal changes in epipelic diatom and ionic composition of a karstic lake, Todurge, in central Anatolia, Turkey
    (Asian Network for Scientific Information, 2007) Sivaci, E. Ridvan; Kilinc, Sabri; Dere, Sukran
    The seasonal variations of epipelic diatoms and ionic composition in Tödürge Lake, the largest karstic lake of Anatolia, were investigated from October 2000 to October 2001. A total of 92 taxa belonging to 29 genera were identified. In all station, Amphora, Achnanthidium, Cymbella, Gomphonema and Mastogloia genera were dominant. Amphora commutata, Achnanthidium minutissimum, Cymbella affinis, Cyclotella comensis, Cocconeis placentula var. euglypta, Gomphonema olivaceum, Mastogloia smithii, Mastogloia braunii, Cymbella sinuata, Cymbella silesiaca and Cymbella naviculaformis were identified. The seasonal distribution of diatoms were affected by sulphate (311 mg L -1) and calcium (489 mg L-1) concentration. © 2007 Asian Network for Scientific Information.
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    Öğe
    Seasonal variation of epilithic diatom Todurge Lake (Sivas)
    (Ege Univ, 2007) Sivaci, E. Ridvan; Dere, Sukran; Kilinc, Sabri
    The seasonal variation of the composition and concentration of epilithic flora of diatom from chosen sampling eight station on Todurge Lake have been investigated and compared between November-2000 and November-2001. In addition, some physical and chemical parameters were measured at lake water. Calcium and Sulfate have been based chemical component in area. Although The species of genus Cymbella, Amphora, Cocconeis, Gomphonema, Achnanthes and Fragilaria constitute the main composition of the epilithic flora of Todurge Lake, howewer the species belonging to genus Navicula, Nitzschia, Epithemia, Gyrosigma, Pinnularia and Stauroneis are found to be less numerous. During the study, Cymbella affinis Kutz., Cocconeis placentula var. euglypta Ehr., Achnanthidium minutissimum Kutz. Czar., Amphora commutata Grunow, Gomphonema olivaceum (Hornemann) Breb., Mastogloia braunii Grunow have been the dominant species in whole station of Todurge Lake. The species of whole diatom except Epithemia argus Kutz., Caloneis clevei (Lagerst.) Cleve, Stauroneis anceps Ehr., Surirella minuta Breb., were found very frequently and numerous in the whole station. Generally, total organism in all of station increased in the late spring and early summer and decreased in the late winter and late summer. The richness and diversity indices were determined the highest in T6 station, the lowest in T1 and T7 station.