Mapping the establishment and invasiveness potential of rainbow trout (Oncorhynchus mykiss) in Turkey: With special emphasis on the conservation of native salmonids

Rainbow trout (Oncorhynchus mykiss) has become by far the most frequently farmed freshwater fish species in Turkey, whereas very little is known about its establishment and invasiveness potential. We explored this potential through a combination of Maxent habitat suitability model and the Aquatic Species Invasiveness Screening Kit (AS-ISK) on the river basin scale by generating an overall risk score (ORS). The outcome of this approach was also incorporated with the spatial analysis of native salmonid species by generating a relative vulnerability score (RVS) to prioritize susceptibility of native species (or populations) and to propose risk hotspots by identifying their potential geographic overlap and interaction with O. mykiss. Results suggest that the northern basins (Eastern Black Sea, Western Black Sea and Marmara basins) are the most suitable basins for O. mykiss. According to the Basic Risk Assessment (BRA) threshold scores, O. mykiss is classified as "high risk" for 3 (12.0%) of the 25 river basins screened (Western Black Sea, Eastern Black Sea and Maritza-Ergene), and as "medium risk" for the remaining basins. The climate change assessment (CCA) scores negatively contributed the overall invasiveness potential of O. mykiss in 22 (88.0%) of the river basins and resulted in zero contribution for the remaining three, namely Aras-Kura, coruh river and Eastern Black Sea. The ORS score of river basins was lowest for Orontes and highest for Western Black Sea, whereas it was lowest for Konya-closed basin and highest for Eastern Black Sea, when CCA was associated. The micro-basins occupied by Salmo rizeensis had the highest mean habitat suitability with O. mykiss. Among the all species, S. abanticus had the highest RVS, followed by S. munzuricus and S. euphrataeus. The overall outcome of the present study also suggests that the establishment and invasiveness potential of O. mykiss may decrease under future (climate warmer) in Turkey, except for the northeast region. This study can provide environmental managers and policy makers an insight into using multiple tools for decision-making. The proposed RVS can also be considered as a complementary tool to improve IUCN red list assessment protocols of species

Impact of nutrients and water level changes on submerged macrophytes along a temperature gradient: A pan-European mesocosm experiment

Submerged macrophytes are of key importance for the structure and functioning of shallow lakes and can be decisive for maintaining them in a clear water state. The ongoing climate change affects the macrophytes through changes in temperature and precipitation, causing variations in nutrient load, water level and light availability. To investigate how these factors jointly determine macrophyte dominance and growth, we conducted a highly standardized pan-European experiment involving the installation of mesocosms in lakes. The experimental design consisted of mesotrophic and eutrophic nutrient conditions at 1 m (shallow) and 2 m (deep) depth along a latitudinal temperature gradient with average water temperatures ranging from 14.9 to 23.9 degrees C (Sweden to Greece) and a natural drop in water levels in the warmest countries (Greece and Turkey). We determined percent plant volume inhabited (PVI) of submerged macrophytes on a monthly basis for 5 months and dry weight at the end of the experiment. Over the temperature gradient, PVI was highest in the shallow mesotrophic mesocosms followed by intermediate levels in the shallow eutrophic and deep mesotrophic mesocosms, and lowest levels in the deep eutrophic mesocosms. We identified three pathways along which water temperature likely affected PVI, exhibiting (a) a direct positive effect if light was not limiting; (b) an indirect positive effect due to an evaporation-driven water level reduction, causing a nonlinear increase in mean available light; and (c) an indirect negative effect through algal growth and, thus, high light attenuation under eutrophic conditions. We conclude that high temperatures combined with a temperature-mediated water level decrease can counterbalance the negative effects of eutrophic conditions on macrophytes by enhancing the light availability. While a water level reduction can promote macrophyte dominance, an extreme reduction will likely decrease macrophyte biomass and, consequently, their capacity to function as a carbon store and food source

The future depends on what we do today – projecting Europe’s surface water quality into three different future scenarios

There are infinite possible future scenarios reflecting the impacts of anthropogenic multiple stress on our planet. These impacts include changes in climate and land cover, to which aquatic ecosystems are especially vulnerable. To assess plausible developments of the future state of European surface waters, we considered two climate scenarios and three storylines describing land use, management and anthropogenic development (‘Consensus’, ‘Techno’ and ‘Fragmented’, which in terms of environmental protection represent best-, intermediate- and worst-case, respectively). Three lake and four river basins were selected, representing a spectrum of European conditions through a range of different human impacts and climatic, geographical and biological characteristics. Using process-based and empirical models, freshwater total nitrogen, total phosphorus and chlorophyll-a concentrations were projected for 2030 and 2060. Under current conditions, the water bodies mostly fail good ecological status. In future predictions for the Techno and Fragmented World, concentrations further increased, while concentrations generally declined for the Consensus World. Furthermore, impacts were more severe for rivers than for lakes. Main pressures identified were nutrient inputs from agriculture, land use change, inadequately managed water abstractions and climate change effects. While the basins in the Continental and Atlantic regions were primarily affected by land use changes, in the Mediterranean/Anatolian the main driver was climate change. The Boreal basins showed combined impacts of land use and climate change and clearly reflected the climate-induced future trend of agricultural activities shifting northward. The storylines showed positive effects on ecological status by classical mitigation measures in the Consensus World (e.g. riparian shading), technical improvements in the Techno World (e.g. increasing wastewater treatment efficiency) and agricultural extensification in the Fragmented World. Results emphasize the need for implementing targeted measures to reduce anthropogenic impacts and the importance of having differing levels of ambition for improving the future status of water bodies depending on the societal future to be expected

İklim değişikliği ve arazi kullanımının Beyşehir gölü ekosistem yapısı ve hizmetleri üzerindeki etkileri.

In this thesis, the main aim was to predict the impacts of climatic and land use changes on the ecosystem structure of Lake Beyşehir with the perspective of ecosystem services. Modeling results revealed the sensitivity of ecological and hydrological dynamics of Lake Beyşehir to climatic changes. Climate change scenarios led to reductions in total inflow rates and water levels, and the results showed that significant reductions in water abstraction are needed to maintain the lake in the future. The outcomes of the current study also indicated an important role of projected land use change on nutrient loading from the catchment, though with minor effects on surface runoff. Although lake models differed in their predictions for future nutrient concentrations and Chlorophyll-a, they both indicated a significant increase in cyanobacteria biomass in the future which may result in degradation of the lake water quality. Analysis of long-term ecosystem services revealed that the lakes’ services varied through time with a declining trend in provisional services (e.g., water level, fisheries), however, increased climate regulation services were recorded throughout the century. The water level was found to be important in affecting supporting services of the lake (e.g., biodiversity). Future projections also indicated that irrigation water service of the lake may decrease in the future considering climate change projections. Furthermore, increased cyanobacteria contribution may also affect the drinking water quality of the lake and may limit the drinking water use for certain periods with cyanobacteria bloom. All in all, the results highlighted that warmer and drier climate may decrease water availability and trigger cyanobacteria bloom that may lead to loss of ecosystem values and services of Lake Beyşehir if necessary adaptation measures are not undertaken.  Ph.D. - Doctoral Progra

Sığ göllerde su seviyesi ve balık avlanma baskısının suiçi bitki gelişimindeki rollerinin mezokozm deneyiyle belirlenmesi.

Four-month mesocosm experiment from June 1st to September 25th, 2009, was conducted to determine the e ffect of water level di erence in combination with fish predation pressure, on submerged macrophyte development, in an eutrophic shallow lake. Eff ect of water level fluctuation was simulated by placing enclosures to the di fferent water depths that included 0.8 m, 1.6 m and 2.3 m on Lake Eymir. These enclosures having a cylindirical shape and 1.2 m diameter, were open to sediment and atmosphere interaction. The highest water level mesocosms were cancelled after fifth sampling due to rapture in the bags, hence this thesis does not include the results of 2.3 m. At each depth, half of the enclosures were stocked with planktivo-omnivorous fish (Tinca tinca, Alburnus spp.) which are natural fauna of Lake Eymir. Before stocking of fish, ten shoots of Potamageton pectinatus were added to all of the enclosures in order to observe submerged macrophyte development. Sampling for physico-chemical parameters, zooplankton, chlorophyll a, PVI% and periphyton was conducted weekly for the first five weeks, last six samplings were done biweekly. Macrophyte harvesting for dry weight estimation was done at the end of the experiment. Throughout the experiment water level decreased 0.41 ± 0.06 m in each enclosures. Water level was so critical for macrophyte development that no significant macrophyte growth was observed in enclosures located at 1.6 m (HW). However, fish predation did not prevent the growth of macrophyte in enclosures located at 0.8 m (LW) but it was important in HW enclosure for a ffecting water clarity. Fish predation a ffected chlorophyll a, zooplankton and nutrient concentrations and the eff ect was mostly pronounced at LW enclosures. They had high chlorophyll a and nutrient concentrations but it did not repress macrophyte growth as in temperate lakes. Despite high water clarity in HW fishless enclosures, very low macrophyte biomass may be attributed to enhanced periphyton development. Zooplankton community shifted to small sized ones under fish predation while fishless enclosures had higher zooplankton /phytoplankton ratio for each depth. Hence, regarding these results it can be stated that decrease in water level can compensate the negative effects of fish predation on macrophyte growth in warm Mediterranean lakes.M.S. - Master of Scienc

İKLİM DEĞİŞİKLİĞİ VE ARAZİ KULLANIMININ BEYŞEHİR HAVZASI ÜZERİNDEKİ ETKİLERİNİN BELİRLENMESİ

İKLİM DEĞİŞİKLİĞİ VE ARAZİ KULLANIMININ BEYŞEHİR HAVZASI ÜZERİNDEKİ ETKİLERİNİN BELİRLENMES

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

İKLİM DEĞİŞİKLİĞİ VE ARAZİ KULLANIMININ BEYŞEHİR HAVZASI ÜZERİNDEKİ ETKİLERİNİN BELİRLENMES

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

İKLİM DEĞİŞİKLİĞİ VE ARAZİ KULLANIMININ BEYŞEHİR HAVZASI ÜZERİNDEKİ ETKİLERİNİN BELİRLENMES