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This study aimed to determine the species composition of two algal associations in Karakaya Dam Lake. For this purpose, monthly variations in species composition of phytoplankton and seasonally variations in epipelic algae occurring in the dam lake were studied between June 2010 and May 2011. Five stations were selected in Karakaya Dam Lake. A total of 38 algal taxa belonging to Bacillariophyta (27 taxa), Charophyta (2 taxa), Chlorophyta (3 taxa), Cyanobacteria (3 taxa), Miozoa (2 taxa) and Ochrophyta (1 taxon) were identified in the phytoplankton. The diatom genera Cocconeis, Cymbella, Fragilaria, Nitzschia, Stauroneis and Surirella were represented with two taxa in the phytoplankton. Ceratium hirundinella was noticed with its continuous occurrence in the phytoplankton throughout the year. A total of 25 algal taxa belonging to Bacillariophyta (21 taxa), Charophyta (1 taxon), Chlorophyta (2 taxa) and Cyanobacteria (1 taxon) were identified in the epipelon. Seasonal variations of algal species with respect to occurrence frequency and abundance were compared and discussed in relation to physical and chemical properties of the dam lake.

Lettuce (Lactuca sativa L.) and African catfish (Clarias gariepinus) were preferred to grow in aquaponics due to their high and fast productivity growth. However, limited research was conducted on the impact on different inorganic substrates‘ growth performance in aquaponics. In this study, lettuce‘s growth performance was determined in four different kinds of inorganic substrates in Nutrient Film Technique (NFT) aquaponics by measuring final weight, daily growth rate, stem diameter, plant and root lengths, leaf number per plant and shoot/root ratio. Polyester fiber, rock wool, zeolite, and gravel were used as inorganic substrate materials. A constant flow rate of 0.3 L/min was maintained using with a submersible pump motor. At the end of the study, the African catfish‘s feed conversion ratio was estimated to be 0.66, while the specific growth rate (SGR) was 2.3%. Total lettuce yields for polyester fiber, rock wool, zeolite and gravel were obtained as 5.072,22 kg/m2, 4.934,03 kg/m2, 6.067 kg/m2, and 5.382,64 kg/m2 respectively. There were statistically significant differences for daily growth rate between the inorganic substrates that the significantly highest values were recorded in the zeolite. The results revealed that initial plant length and shoot/root ratio were the significant factors on the growth performance for lettuce in aquaponic system tested. The best lettuce yield performance was observed in zeolite substrate but, economically available option was found as gravel for hydroponic troughs.

The authors acknowledge COST Action ES 1105 "CYANOCOST Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management" and COST Action Global Change Biology ES 1201 NETLAKE -Networking Lake Observatories in Europe" for contributing to this study through networking and knowledge sharing with European experts in the field. We acknowledge the members of the Global Lake Ecological Observatory Network (GLEON) for their collaborative spirit and enthusiasm that inspired the grassroots effort of the EMLS. E.M. was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis. We thank Pieter Slot for assisting with the pigment analysis. We thank Dr. Ian Jones for valuable feedback on an earlier version of the manuscript. We thank the Leibniz Institute of Freshwater Ecology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart, and the Leibniz Association for financial support. H.P. was supported by the US National Science Foundation (1840715, 1831096). A.C.'s work was funded by the Spanish Agencia Estatal de Investigacion and EU funds through the project CLIMAWET (CGL2015-69557-R). The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland. We are grateful to Kristiina Vuorio from the Freshwater Centre of the Finnish Environment institute for her help in organizing, collecting and analysing samples by the University of Jyvaskyla and to Gerald Dorflinger from the Water Development Department of Cyprus for his assistance with the sampling in Cyprus and for granting the CUT team permission to use WDD's equipment. Finally, we would like to thank the numerous other assistants that helped realizing each local survey. Open access funding provided by Universite de Geneve., To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature., European Cooperation in Science and Technology (COST) ES 1105 ES 1201, Swiss State Secretariat for Education, Research and Innovation, University of Geneva, Leibniz Association, National Science Foundation (NSF) 1840715 1831096, Spanish Agencia Estatal de Investigacion, European Commission CGL2015-69557-R, Department of Agriculture, Environment and Rural Affairs, Northern Ireland

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. © 2018 by the authors. Licensee MDPI, Basel, Switzerland., The authors acknowledge COST Action ES 1105 “CYANOCOST—Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE—Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from the University of Geneva. We thank Clare Ahnlund, Ena Suarez and Irene Gallego for helping out with the Swiss survey. We thank Wendy Beekman and Els J. Faassen for the nutrient and toxin analysis.

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment., The authors acknowledge COST Action ES 1105 “CYANOCOST – Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE – Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis and the University of Wageningen for covering the costs of this analysis from the personal funding of dr. Miquel Lürling. We thank Pieter Slot for assisting with the pigment analysis and the University of Amsterdam for covering the costs of the analysis through funding from the group of Prof. Jef Huisman and dr. Petra Visser (IBED). We would like to thank the Environmental Data Initiative for covering the cost of archiving the EMLS dataset. We would like to thank the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Dept. of Experimental Limnology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart; and the Leibniz Association for financial support. The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland.

This study aimed to determine the physicochemical characteristics of the water quality and trophic state of Akgöl Lagoon located in the eastern Mediterranean. Cluster analysis clearly revealed the spatial heterogeneity classifying sampling stations as saline and freshwater/brackish water sites. A multivariate analysis of variance followed by principal component analysis supported that salinity was major factor affecting physicochemical water quality variations in the lagoon. As salinity was mainly governed by freshwater inflows depending on agricultural irrigation, it can be proposed that water quality was significantly influenced from freshwater use by human activities. The parameters used as predictors (total nitrogen, total phosphorus, chlorophyll a and Secchi disk transparency) yielded different trophic states for the lagoon. However, as chlorophyll is a better predictor than the other indices, it was concluded that the Akgöl Lagoon is at mesotrophic status.

Some physicochemical variables and climatic effects on the succession of a diatom community in the plankton of the pelagic zone of Lake Hazar, an alkaline soda lake, were investigated. Monthly diatom samples were collected from the surface water at western, central, and eastern pelagic areas of the ellipsoid-shaped lake using a plankton net from November 2004 to October 2005. When high temperature and pH levels prevailed in May and September, Epithemia, Rhopalodia, Cocconeis, and Cyclotella were dominant. Cymbella was dominant in early spring and late autumn, but was not significantly correlated with temperature or pH. The species of Gomphonema, Fragilaria, Navicula, and Nitzschia were dominant at low temperature and pH levels in winter. However, the diatom community of the surface phytoplankton in the lake comprised largely cosmopolitan and nonplanktonic species of Cocconeis, Cyclotella, Cymbella, Epithemia, Fragilaria, Gomphonema, and Rhopalodia detached from benthic habitats of littoral zone by wind-driven currents.

This study aimed to explain the seasonal and vertical distribution of phytoplankton in the pelagic zone of a deep alkaline lake that is characterized by low phytoplankton abundance. Phytoplankton and water samples were collected seasonally from 9 points and 7 depths between the surface and 20 m from December 2004 to September 2005. Planktolyngbya contorta was the dominant or subdominant species in all seasons and depths. The dominance of Gomphonema species was observed in December, but they were subdominant in September. Cyclotella meneghiniana was dominant at 20 m and subdominant in the upper depths during March, June, and September. Melosira sp. and Meridion circulare were the dominant taxa of the surface phytoplankton in March and June, respectively. A nonparametric test showed the prevalence of cyanobacteria and green algae at a depth of 10 m. Principal component analysis showed the effect of temperature, pH, dissolved solids, nitrate, and silica on the abundance and distribution of phytoplankton. The generalized linear model revealed that high pH and high dissolved solids content seemed to affect the abundance of phytoplankton via limiting nutrient availability.

Bu çalışmada Işıktepe Baraj Gölü'nün (Maden, Elazıð) kıyı bölgesinde üç noktada Nisan 2011 ile Mart 2012 arasında 12 ay süresince yürütülen su kalitesi izleme araştırmasından elde edilen ilk bulgular deðerlendirilmiştir. Araştırma süresince sıcaklık, çözünmüş oksijen, doygunluk, pH, elektriksel iletkenlik, toplam sertlik, toplam alkalinite, kimyasal oksijen ihtiyacı, çözünmüş anyon ve katyonlar (lityum, sodyum, potasyum, kalsiyum, magnezyum, amonyum, nitrat, florür, fosfat, klorür, bromür ve sülfat) ile toplam fosfor izlenmiştir. Işıktepe Baraj Gölü düşük çözünmüş iyonik madde içeriðine nedeniyle düşük elektriksel iletkenlik ve çözünmüş katı madde içeriðine sahip orta sert sulu alkali bir göl olarak karakterize olmuştur. Yüzeysel Su Kalitesi Yönetimi Yönetmeliði A ve B grubu parametreleri bakımından baraj gölü “yüksek kaliteli” ve “az kirlenmiş” sınıflarına dâhil olmuştur. Baraj gölünün inşa amacı olan tarımsal sulama yanı sıra içme suyu temini, alabalık ve diðer balıkların yetiştiriciliði ile hayvan üretimi ve çiftlik ihtiyacı için de kullanılabileceði sonucuna ulaşılmıştır., Giriş© Su Ürünleri Merkez Arastırma Enstitüsü Müdürlügü, Trabzon Işıktepe Baraj Gölü (Maden, Elazıð) Kıyı Bölgesi Fizikokimyasal Su Kalitesi Üzerine Ýlk BulgularMehmet KÜÇÜKYILMAZ *, Gürel N. ÖRNEKCÝ , Ali A. USLU , Nurten ÖZBEY , Tunay ŞEKER , Nevin BÝRÝCÝ , Nurettin YILDIZ , Mehmet Ali T. KOÇERSu Ürünleri Araştırma Ýstasyon Müdürlüðü, Sürsürü Mah., Şehit Polis M. Lami Karaaðaç Sokak, No: 9, 23040, Elazıð, TürkiyeAkdeniz Su Ürünleri Araştırma Üretme ve Eðitim Enstitüsü Müdürlüðü, AntalyaBu nedenle, akarsu özelliði gösteren Işıktepe Barajı, Elazıð ili Maden ilçesi (riverine), geçiş (transitional) ve göl özelliði sınırlarında yer alan Seyrek Deresi üzerinde gösteren (lacustrine) bölgeler olmak üzere üç sulama amacıyla inşa edilmiştir. 10 yılı aşkın kavramsal bölgeyle deðerlendirilirler. Çoðunsüredir su tutmuş olmasına karşın, baraj lukla akarsu taşkın vadilerinde yapay olarak gölünün su kalitesi üzerine herhangi bir çalışma oluşturulan baraj gölleri su toplama havzası ve yapılmamıştır. Bu çalışmayla, gelecek çalışgöl havzası morfolojisi bakımından doðal malara ışık tutması bakımından, Işıktepe Baraj göllerden farklılaşır. Bu iki temel farklılıðın Gölü'nün kıyı bölgesinde su kalitesi üzerine sonucu olarak, daha geniş bir su toplama elde edilen ilk bulguların deðerlendirilmesi havzasına sahip olan baraj gölleri, derinlik amaçlanmıştır.eðimi, litoral bölge habitatları, sıcaklık tabaklaşması ve karışımlar gibi özellikleriyle Materyal ve Metotde doðal göllerden ayrılırlar (Kimmel ve Seyrek Deresi üzerinde kurulu olan Groeger, 1984; Palau, 2006).Işıktepe Baraj Gölü 38°26? N ve 39°31? E Çeşitli avantajları dikkate alındıðında coðrafi konumlarında bulunmaktadır. Deniz enerji üretimi bakımından baraj gölleri termik seviyesinden yüksekliði 1280 m olan normal su ve nükleer santrallere kıyasla ön plana çıkmış kotunda 0,35 km yüzey alanına, 4,47 hm (Karadeniz vd., 2011) ve Türkiye'de bu depolama hacmine, yaklaşık 12 m ortalama öncelikli amaçla 700'e yakın baraj ve 500'ün derinliðe ve 4,2 km kıyı şeridi uzunluðuna sahip üzerinde hidroelektrik santral inşa edilmiştir olan baraj gölü, inşaatı 1999 yılında tamam(Küçükyılmaz vd., 2010). Genel olarak, lanmış olan genç bir rezervuardır. Baraj gölü barajlar ve göletler, elektrik üretimi, içme suyu havzasının kuzey ve kuzeydoðu kesiminde temini, tarımsal sulama, balıkçılık, sel kontrolü kalan 313 ha tarım arazisinin sulanması için ve rekreasyon gibi amaçlarla inşa edilirler kullanılmaktadır (Anonim, 2005; 2013). Su (Mason, 2002). Bir baraj gölünün fizikotoplama havzası ve gölü besleyen ana akarsu kimyasal su kalitesi, sucul tür çeşitliliði ve insan kaynaklı bir noktasal ve yayılı deşarja bolluðu oluştuðu akarsuyunkine kıyasla maruz kalmamaktadır.belirgin deðişiklikler gösterir. Bu nedenle yeni Baraj Gölü'nün su kalitesi üzerine ilk oluşan bir baraj gölünde doðal kaynakların bilgileri elde etmek amacıyla örnekleme sürekli izlenmesi gerekmektedir (Yılmaz, çalışmaları gölün farklı alanlarını temsil 2004). Ýçme suyu temini için kullanılan baraj edebilecek şekilde ve sürekli ulaşılabilirliði göllerinde su kalitesinin içme suyu stanmümkün olan rastgele 3 kıyı noktasında (Şekil dartlarına uygunluðu önemli olduðundan, 1) Nisan 2011 ile Mart 2012 arasında aylık baraj yönetimi ve su kalitesine yönelik olarak yürütülmüştür. Bununla birlikte, Aralık sorunların anlaşılması bakımından izleme 2011'de yalnızca ilk örnekleme noktasından programlarıyla ekosistemin işleyişinin anlaşılörnek alınabilmiş, göl yüzeyi donmuş ması gerekmektedir (Tüzün vd., 2006). olduðundan cak, Şubat ve Mart 2012 aylarında Gerçekten, bir su kaynaðının etkin kullanımını ise örnekleme yapılamamıştır. Su örnekleri saðlamak için, öngörülen beklentileri karşılakıyıda elle daldırma yöntemi ile alınmış, yacak bir izleme programını titizlikle yürüörnekler 1 L hacimli polipropilen şişelere terek kaynak hakkında bilgi toplanması konulmuş ve aynı gün içerisinde laboratuvara zorunludur (Şen ve Koçer, 2003).ulaştırılmıştır. Sıcaklık, çözünmüş oksijen ve oksijen düşük sıcaklık 2,3 °C olarak Aralık (2011) doygunluðu HACH HQ30d, pH ve elektriksel ayında ve en yüksek sıcaklık 27,9 °C olarak iletkenlik ise HACH HQ40d model ölçüm Temmuz (2011) ayında ölçülmüştür. Örnekcihazlarıyla arazide ölçülmüştür. Toplam leme süresince pH deðeri 7,5-9,3 arasında sertlik hesaplama metoduyla, toplam alkalinite ölçülmüş ve baraj gölü alkali karakterli olarak potansiyometrik titrasyon metoduyla ve (ortalama 8,6±0,5) belirlenmiştir. Sıcaklıkla kimyasal oksijen ihtiyacı açık geri damıtma istatistiksel olarak önemli bir korelasyonu metoduyla tayin edilmiştir (APHA vd., 1998). belirlenmeyen elektriksel iletkenlik ise 167Lityum, sodyum, potasyum, kalsiyum, 227 µS/cm arasında ölçülmüştür. Sıcaklık magnezyum, amonyum, nitrit, nitrat, florür, deðişimiyle ileri derecede güçlü bir ilişki fosfat, klorür, bromür ve sülfat Dionex ICS sergileyen (R = -0,94; P < 0,05) çözünmüş Model kullanılarak iyon kromatografik oksijenin ortalama miktarı 8,9±1,3 mg/L metotla, toplam fosfor ise hazır kit kullanılarak (%112±6 doygunlukta) olarak hesaplanmıştır Merck Nova 60 spektrofotometre ile tayin (Tablo 1, Şekil 2).edilmiştir.Toplam sertlik araştırma süresince 90Deðişkenlerin normalitesi Shapiro 110 mg CaCO /L arasında (ortalama 101±5 mg Wilk's testiyle kontrol edilmiştir. Normal CaCO /L) tayin edilmiş ve sularda sertliðin daðılım gösteren deðişkenler için tek yönlü nedeni ana iyonlar olan kalsiyum ve magANOVA ve normal daðılım göstermeyen nezyumla güçlü ilişkiler (sırasıyla R = 0,87 ve deðişkenler için Wilcoxon testini takip eden R = 0,66; P < 0,05) göstermiştir. Toplam Student t-testi kullanılarak istasyonlar alkalinite ise örnekleme noktalarında en düşük arasındaki farklılıðın istatistiksel önemi 98 mg CaCO /L ve en yüksek 148 mg CaCO /L belirlenmiştir. Ýzlenen deðişkenler arasındaki olarak daha geniş bir aralıkta deðişim ilişkiler Spearman's çoklu korelasyon testiyle göstermiştir (Tablo 1, Şekil 2).belirlenmiştir. Deðişkenlerin varyasyondaki gücünü ve yönünü belirlemek için çok deðişkenli analiz yöntemi olan Ana Bileşenler Analizi (PCA) uygulanmıştır. Su kalitesi sınıflandırması Yüzeysel Su Kalitesi Yönetimi Yönetmeliði'ne göre yapılmış ve karakteristik deðerin bulunması için Hazen yöntemi kullanılmıştır (Anonim, 2012). Ýstatistiksel analizler için JMP 8 ve CANOCO yazılımları kullanılmıştır.Sonuçlar ve Tartışma Çalışma süresince Işıktepe Baraj Gölü'nde izlenen deðişkenlerin örnekleme noktaları arasındaki zamansal ve alansal varyasyonu (Şekil 2) istatistiksel olarak önemli bulunmamıştır (P > 0,05). Mevsimsel hava sıcaklıðı deðişimlerine uygun bir eðilimle, en Şekil 1. Işıktepe Baraj Gölü ve örnekleme noktaları.

This study was conducted to determine the effects of zeolites on total ammonia nitrogen (TAN) removal during a 24-hour-sea bass transport. Five experimental treatments (0 (control), 10, 20, 30 and 40 g/l zeolite) with 3 replications were applied in 14 l plastic tanks. 90 sea bass (total weight 175.07 ± 0.49 g) were stocked in each tank. The zeolites were placed in mesh bags and renewed 8 and 16 hours (h) after the commencement of transfer. TAN contents of tank waters were measured after 8, 16 and 24 h. The results revealed that at the 8th h, 20, 30 and 40 g/l zeolite doses were significantly effective compared with the control. At the 16th and 24th h the lowest zeolite level (10 g/l) was also effective in TAN removal. In general highest TAN removal was achieved with 40 g/l treatment with efficiencies of 18.33%, 34.08% and 20.96% at the 8th, 16th and 24th h respectively. Overall, the results suggest that the use of zeolite in sea bass transportation could bring remarkable benefits and thereby increase fish transportation density and welfare.

This study aimed to check the effectiveness of water quality indices (WQIs) in the specific assessment of trout culture impacts on a stream water quality by selecting the parameters in various approaches. Water quality was monitored monthly for a period of 1 year in one reference point and four affected stream reaches in which discharges from intensive trout farms, and rural and agricultural activities were present. The objective WQI calculation using 24 parameters and the minimum WQI (WQI(min)) using dissolved oxygen, biochemical oxygen demand, total suspended solids, total phosphorus, ammonia nitrogen (NH4+-N), and total nitrogen as major indicators in trout farm effluents could not distinguish the aquaculture-impacted stream reaches. However, WQI(min) calculation with NH4+-N, total organic nitrogen (TON), soluble reactive phosphorus, and total organic phosphorus which were selected using the principal component analysis findings meaningfully classified the sampling points. Further reduction of parameters to NH4+-N and TON in WQI(min) calculation achieved a similar successful classification of the sampling points. This study showed that WQI(min) calculated using NIH4+-N and TON is a useful and easily applicable methodology in the assessment of the impacts of trout farm effluents on the stream water quality. (C) 2013 Elsevier Ltd. All rights reserved.

Pollution of surface water has become one of the most important environmental problems. Two types of large and long-lasting pollution threats can be recognized at the global level: on the one hand, organic pollution leading to high organic content in aquatic ecosystems and, in the long term, to eutrophication. It is a well-known fact that polluted water can reduce water quality thus restricting use of water bodies for many purposes.

This study aimed to reveal the vertical and seasonal fluctuations in water quality of Keban Dam Reservoir, which is the second largest dam of Euphrates Basin in Turkey. Temperature, dissolved oxygen, pH, electrical conductivity, some cations and anions content were monthly monitored in water column between 0 and 30 meters over a twelve-month period from Febru-ary 2010 to January 2011. The thermal stratification was observed between June and August. Epilimnion extended up to depth of 10 meters and hypolimnion occurred below a depth of 20 meters. A decrease was recorded for dissolved oxygen below the epilimnion whereas for cal-cium and bicarbonate in the epilimnion during thermal stratification. The other cations and ani-ons were nearly uniform in water column. The study showed significant relations of physico-chemical variables in water column of the reservoir.

In this study, some physicochemical properties of surface waters of the lower Euphrates Basin in the Southeastern Anatolia region were investigated. The water sources investigated are Ataturk, Birecik, Karkamis and Haci Hidir Dam lakes and Euphrates River together with eight streams which are major running waters of the sub-basin. Total 20 variables consisting of temperature, pH, electrical conductivity, dissolved oxygen, turbidity, total dissolved and suspended solids, biochemical oxygen demand, total hardness, total alkalinity, calcium, magnesium, sodium, potassium, chloride, fluoride, sulfate, ammonia nitrogen, nitrate nitrogen and reactive phosphorus were monitored in surface waters. Significant relationships between dissolved ions, conductivity, hardness and alkalinity were observed. While most of the surface waters had middle hard and slightly alkaline characteristics with moderate dissolved solids and low organic matter content, Haci Hidir Dam lake and Nizip Stream separated from them in terms of investigated variables. © Medwell Journals, 2010.