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We studied feeding behavior and prey selection of topmouth gudgeon (Pseudorasbora parva), big-scale sand smelt (Atherina boyeri) and pike-perch (Sander lucioperca) in Lake Egirdir, the second largest freshwater lake in Turkey. Fish specimens were collected between January and August in 2010 and 2011 using gill-nets and purse seines. A total of 941 specimens were analyzed for stomach contents analysis. We expressed the importance of the food items present in their guts with the relative importance index (IRI) and estimated their diet selectivity indices with Pearre’s index. Pseudorasbora parva had a diverse diet comprising mainly Nitokra hibernica (copepod), Chydorus sphaericus, and Bosmina longirostris (cladoceran) (each, at p 0.05). Big-scale sand smelt often preferred B. longirostris, N. hibernica, and Alona quadrangularis (each at p 0.05), Carassius gibelio was not preferred by pike-perch as food item (p > 0.05). Our results indicate that invasive species altered the food chain in Lake Egirdir. Thus, because these fish species constitute a major threat for native fish species for food and breeding grounds, extensive care should be taken to prevent invasive fish species entering lakes in Turkey.

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

Feeding ecology and prey selection of sand smelt (Atherina boyeri, Risso, 1810) were investigated by taking monthly samples (January to December 2010) at four stations of Lake Egirdir, (Turkey) using gill nets (mesh sizes 10–100 mm) and purse‐seines (mesh size 6 mm). A total of 49 out of 612 analysed stomachs were empty (8.01%); stomach contents included eight major prey categories: zooplankton, phytoplankton, Arachnida, Arthropoda, Insecta, fishes as well as unidentified organisms and remains. Dominant prey items included cladocerans (Bosmina longirostris [% N = 67.92], Alona quadrangularis [% N = 5.06]), copepods (Nitokra hibernica [% N = 9.30], Mesocyclops leuckarti [% N = 3.35]), and arthropoda (Corophium curvispinum [% N = 3.46]). The importance of Insecta, Arthropoda, fishes, and unidentified eggs increased in the diet with increasing size of the sand smelt, whereas the contribution of Cladocera and Copepoda decreased. Sand smelt strongly preferred B. longirostris (selectivity index V = 0.639, χ² = 81.689, p

In this research, a preliminary study on zooplankton species was conducted a total of 7 in the freshwater areas in the Mediterranean, Aegean and Central Anatolia region of Turkey. Zooplankton sampling were collected one-time study between 2002 and 2012 from the study areas. Samples were taken using plankton net Hydrobios with a mesh size of 55 μm and preserved with 4% formaldehyde solution. At the end of the study, a total of 43 species were identified, including 20 species Rotifera, 18 species Cladocera, 5 species Copepoda. Pleuroxus aduncus, Chydorus sphaericus, Bosmina longirostris, Leydigia leydigi, Keratella cochlearis and Asplanchna priodonta were observed as intensive during the study area. All species have been recorded for the first time in this study regions.

Bu çalışmanın amacı Işıklı Gölü’ndeki sazan populasyonunun (Cyprinus carpio L., 1758) büyüme özelliklerini incelemektir. Ocak - Aralık 2004 tarihleri arasında yakalanan toplam 158 adet sazan örneği yakalanmış ve erkek: dişi oranı 0.92:1.00 olarak bulunmuştur. Çatal boyları 11.8-80.0 cm ve ağırlıkları ise 36.0-9700.0 g arasında değişmiştir. Bireylerin yarıdan fazlası (%53.2) 21.0-41.0 cm arasındaki boy gruplarında temsil edilmiştir. İncelenen örnekler I-XIV yaşları arasında bulunmuştur. Dişi ve erkek karışımı tüm bireyler için boy - ağırlık ilişkisi W=0.035*L2.841 ve büyüme parametreleri ise; L∞= 108.40, k=0.101ve to= -0.221 olarak hesaplanmıştır. Ortalama kondisyon faktörü ise 1.920 olarak bulunmuştur

Bu araştırma İznik Gölü’nde Ocak-Aralık 2006 tarihleri arasında yapılmıştır. Araştırma boyunca 55 erkek, 64 dişi olmak üzere toplam 119 sazan yakalanmıştır. Sazan örneklerinin yaşları I-X, çatal boyları 8.8-70.4 cm, ağırlıkları 14-7362 g arasında değişim göstermiştir. Boy-ağırlık ilişkisi denklemi W=0.025567Lolarak belirlenmiştir. ,kondisyon faktörü dişilerde 1.983±0.097, erkeklerde 1.958±0.070

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.

Menzelet Barajı ve Fırnız Çayı’ndan Ağustos 2011 ve Kasım 2012 tarihleri arasında elektro-şoker ile yakalanan Capoeta angorae bireylerinin yaş, büyüme oranları ve otolit (asteriskus) morfometrik ölçümleri belirlenmiştir. Toplam boy (L) aralığı 7.5 ile 27.0 cm arasında olan C. angorae bireylerinden elde edilen toplam 175 adet otolit analizlerde kullanılmıştır. Toplam erkek : dişi oranı (E : D = 1.52 : 1.00) erkekler lehine eğimlidir. Student’s t-test cinsiyetler arasında boy farklılığının istatistiksel olarak önemli olduğunu göstermektedir (P < 0.05). Boy – ağırlık ilişkisi dişiler için, W= 0.0128L2.8703 (R2= 0.975), erkekler için, W = 0.0103L2.9462 (R2 = 0.969) ve tüm bireyler için W = 0.0097L2.9629 (R2 = 0.978) olarak hesaplanmıştır. Otolit boyu (OL), eni (OW) ve yarıçapı (OR) sırasıyla 1.67 – 3.45 mm; 1.39 – 2.82 mm ve 0.89 – 1.70 mm olarak ölçülmüştür. Von Bertalanffy büyüme denklemi ise dişiler için, L∞ = 27.55 cm (L), K = 0.465 (yıl-1), t0 = -0.539 (yıl), females; L∞ = 22.84 cm (L), K = 0.772 (yıl-1), t0 = -0.71 (yıl) males; L∞ = 42.25 cm (L), K = 0.102 (yıl-1), t0 = -2.84 (yıl) olarak hesaplanmıştır. Otolit morfometrik ölçümleri (OL, OW ve OR) ile toplam boy arasında kuvvetli doğrusal ilişki olduğu tespit edilmiştir. Gözlenen yaş ile otolit morfometrik ölçümleri sonucu tahmin edilen yaş arasında istatistiksel olarak önemli derecede fark bulunamamıştır (Mann-Whitney U test; P > 0.05)

Background. Capoeta erhani Turan, Kottelat et Ekmekçi, 2008 has an economic importance in commercial and recreational fisheries in Turkey. Knowledge of the biology of this species is very scarce. Despite the importance of this species, no research on the population dynamics such as age and growth rates has been conducted. The aim of this study was to determine the age, growth rate, and the relations between the fish size and the otolith size for C. erhani from the Menzelet Reservoir, Turkey. Materials and methods. This study was carried out seasonally in the Menzelet Reservoir, between January and December 2012. Samples were collected using gill nets with mesh sizes ranging from 18 to 30 mm. Results. A total of 134 otoliths obtained from Capoeta erhani that ranged from 15 to 33.8 cm TL were used in the analyses. The overall male : female ratio (M : F = 1.25 : 1.00) was biased in favour of males. The Mann–Whitney test revealed significant differences between sexes, regarding TL (P < 0.05). The calculated length–weight relations were TL = 0.0097W3.0015 (r2 = 0.986) for females, TL = 0.0054W3.2011 (r2 = 0.975) for males, and TL = 0.0075W3.0892 (r2 = 0.979) for all specimens combined. The von Bertalanffy growth models were L∞ = 33.83 cm (TL), K = 0.964, t0 = –0.573 for females; L∞ = 32.02 cm (TL), K = 0.843, t0 = –0.562 for males; L∞ = 33.85 cm (TL), K = 0.821, t0 = –0.482 for all specimens. Conclusion. This study provides the first information on age, growth, and otolith morphometric parameters of Capoeta erhani. Determining the parameters of C. erhani age and growth rates will lead to the estimates of relevant parameters of population dynamics and to better understanding of the long-term changes of the stock sizes.

Enne (Kutahya), Kayabogazi (Kutahya) ve Porsuk (Eskisehir) Baraj Golleri’nin zooplankton turlerindeki mevsimsel degisimler 2007 Ilkbahar ve 2007 Sonbahar arasinda incelendi. 21 tur Rotifera, 4 tur Cladocera ve 2 tur Copepoda olmak uzere toplam 27 tur tespit edildi. Tespit edilen turlerin tamami Enne, Kayabogazi ve Porsuk Baraj Golleri’nden ilk kez bildirilmektedir

Işıklı Gölü’nde Mart 2003-Şubat 2005 tarihleri arasında yürütülen bu çalışmada, Ocak-Aralık 2004 tarihleri arasındaki örneklemelerden elde edilen Turna balığının büyüme özellikleri araştırılmıştır. Toplam 313 adet Turna incelenmiş ve örneklerin çoğunluğunu dişi bireyler oluşturmuştur. Dişi:erkek oranı 1.68:1.00’dir. İncelenen Turna balığı örneklerinin çatal boyları 21.0 cm (68.0 g) ile 66.0 cm (3342.0 g) arasında değişmiştir. Toplam 7 yaş grubu tespit edilmiş olup dişiler I-VI ve VIII, erkekler ise I-VI yaşları arasında bulunmuştur. Boy ağırlık ilişkisi erkeklerde W= 0.003*L3.298, dişilerde W= 0.005*L3.186 ve tüm örnekler değerlendirildiğinde ise W=0.004*L3.208 olarak bulunmuştur. Populasyonda büyüme değişkenleri erkekler için; L∞= 118.1, K= 0.067, to= -1.966, dişiler için L∞= 117.8, K= 0.067, to= -2.358 ve dişi erkek karışık değerlendirildiğinde ise L∞= 106.8, K= 0.077, to= 2.134 olarak hesaplanmıştır. Ortalama kondisyon faktörü erkekler için 0.884±0.013, dişiler için 0.863±0.007 ve erkek dişi karışımı bireyler için 0.870±0.007 olarak hesaplanmıştır. Kondisyon faktörü değeri eşey gruplarında farklılık göstermemektedir

Summary The length–weight relationships for eight freshwater fish species collected from Beysehir Lake, Egirdir Lake, Aksu River, Alara River, Goksu River and Menzelet Reservoir, were analysed. This paper represents the first LWR references for four of these species and also four of these species are endemic to Turkey.

Summary Diet composition and prey selection of pike (Esox lucius) were studied in Civril Lake, Turkey. The lake is eutrophic in character with a surface area of ca. 64 km−2 and mean depth of 3 m. Stomach contents of 409 specimens were collected between October 2003 and April 2005. Pike diet included 10 prey fish species, two Crustaceae, four Insecta, one Hirudinae and one Amphibia. Feeding was homogeneous, with most pike specializing in prey fish and a few pike specializing on miscellaneous items. Feeding activity varied by season and ontogeny. Stomach fullness and the percentage of fish with prey were highest in spring and in small pike, while feeding intensity was lowest in winter and in large sized pike. Diet composition was dominated by fish, including Carasius gibelio, Chondrostoma meandrense, Esox lucius, Gambusia affinis, Gobio gobio, Hemigrammocapoeta kemali, Leuciscus cephalus, and Tinca tinca. Crustacea were also a significant component in spring and in small sized pike. The most important prey items were C. meandrense, Gammarus sp., H. kemali, and L. cephalus. Pike feeding in winter and summer was homogeneous, specializing mainly on fish as prey, while the diet in spring and autumn was heterogeneous with some pike specializing on Gammarus sp. Cannibalism at 8.7% was observed only in the large sized pike (>40 cm). Pike strongly preferred C. meandrense (Selectivity index V = 0.372; χ2 = 27.739; P 0.05).