The Impacts of climate change and land use on the ecosystem structure and services of Lake Beyşehir

Bucak, Tuba
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.