Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

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.Peer reviewe

A Preliminary Study on Zooplankton Species in Different Aquatic Habitats of Anatolia (Turkey)

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

Karanfil Yağı, Eugenol ve 2-Phenoxyethanol’ün Yağ Balığı Pseudophoxinus anatolicus (Hankó, 1925)’ da, Anestetik Madde Olarak Etkinliği

Bu çalışmada, yetiştiriciliği yapılan yağ balığı, Pseudophoxinus anatolicus (Hankó, 1925) üzerinde karanfil yağı, 2-phenoxyethanol (PE) ve eugenol’ün farklı konsantrasyonlarının etkinliği araştırılmıştır. Bayılma sürelerine göre, en uygun konsantrasyon karanfil yağı için 125 µl L-1 (187,00 ± 62,33 s), PE için 1250 µl L-1 (174,57 ± 28,87 s) ve eugenol için 125 µl L-1 (170,00 ± 39,73 s) olarak belirlenmiştir. Anestetik maddelerin farklı konsantrasyonları, balıkların göstermiş olduğu fiziksel tepkiler üzerinde direk etkili olmuştur (P<0,05). PE ve eugenol’ün artan konsantrasyonlarına bağlı olarak bayılma sürelerinde düşüş ölçülse de aradaki fark istatistik açıdan önemsiz bulunmuştur (P>0,05). En kısa ayılma süreleri ise, 457,57 ± 56,38 s ile karanfil yağı (125 µl L-1), 338,00 ± 20,49 s ile PE (500 µl L-1) ve  510,17 ± 94,07 s ile eugenol (125 µl L-1) gruplarında ölçülmüştür. Sonuç olarak, her üç anestetik madde de yağ balığı yetiştiricilik uygulamalarında verimli bir şekilde kullanılabilir

İznik Gölü (Bursa/Türkiye)’ndeki Gümüşi Havuz Balığının (Carassius gibelio Bloch, 1782) Büyüme Özellikleri

Bu çalışmada, İznik Gölü’nde bulunan Gümüşi Havuz Balığı (Carassius gibelio Bloch, 1782)’nın büyüme özellikleri belirlenmiştir. Ocak - Aralık 2006 tarihleri arasında yakalanan 3114 adet (1060 erkek, 2054 dişi) balığın yaş ve eşey kompozisyonu, yaş-boy, yaş-ağırlık, kondisyon faktörü, oransal boy ve ağırlık artışları tespit edilmiştir. Populasyondaki bireylerin 0-VI yaşlar arasında dağılım gösterdiği, II. yaş grubunun diğer yaşlara oranla daha baskın olduğu saptanmıştır. Yaş gruplarına göre ortalama boy ve ağırlığın 8,8±0,021 cm ile 30,9±0,271 cm ve 14,4±0,079 g ile 764,8±13,733 g arasında değiştiği saptanmıştır. Populasyonu oluşturan bireylerin boy-ağırlık ilişkisi W=0,015756L3,125 ve kondisyon faktörü 2,350±0,014 olarak bulunmuştur

Increased Water Abstraction and Climate Change Have Substantial Effect on Morphometry, Salinity, and Biotic Communities in Lakes: Examples from the Semi-Arid Burdur Basin (Turkey)

Global warming and altered precipitation patterns are predicted to intensify the water loss in semi-arid and arid regions, and such regions in Turkey will be particularly affected. Moreover, water abstraction, not least for irrigation purposes, is expected to increase markedly, posing major threats to the water balance of the lakes and thus their biodiversity. Among the closed basins in Turkey, the Burdur Closed Basin (BCB), located in the southwest of Turkey, is expected to be most affected. The BCB includes several types of aquatic ecosystems which support high biodiversity, including one Ramsar site, six Important Bird Areas, and a considerable richness of native and endemic fish species. Therefore, it is essential to analyze the potential environmental impacts of climate change and increased water abstraction on BCB lakes and their biotic communities. Here, we combined historical data on ecosystems as well as meteorological, remote sensing, and ground-truth data to analyze the changes in the temperature and precipitation of the BCB, water surface areas, and land use, as well as the potential effects on waterbird and fish communities. We calculated the water budget to elucidate water availability in the basin over the last few decades and predicted future conditions based on rainfall and temperature forecasts using climate models. The Standardized Precipitation–Evapotranspiration Index (SPEI) was used to relate the water surface area to precipitation and temperature change in the basin. Crop-farming irrigation in the BCB has increased notably since 2004, leading to intensive water abstraction from the lakes and their inflows, as well as from ground water, to meet the increased demand for irrigation. The water abstraction from the lakes, inflows to the lakes, and the groundwater in the basin has increased the water loss in the catchment substantially. Remotely sensed data on lake surface areas showed a major shrinkage of shallow lakes in the last 40 years. Moreover, the largest lake in the basin, Lake Burdur, lost nearly half of its surface area, which is worrisome since the shallower areas are the most suitable for supporting high biodiversity. Climate models (CNRM-ESM2-1GCM for temperature and GFDL-ESM4-GCM for precipitation) suggest that from 2070, the BCB will face long-term, moderate-to-severe dry periods. This, and the increased demand for water for irrigation, along with climate change, may accelerate the drying of these lakes in the near future with devastating effects on the lake ecosystems and their biodiversity

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

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.Peer reviewe