•Water quality deterioration, namely eutrophication of lakes was well defined in Northern temperate lakes. But there is not sufficient data for semi-arid regions.
Clear Water State:
Turbid Water State:
Alternative Stable States
As a consequence of the alternative stable states the lake shows hysteresis in response to changes in nutrient loading.
•Reduced external loading
- Biomanipulation is a useful tool for lake restoration.
- It is based on top-down control of phytoplankton by either adding piscivorous fish or removal of planktivorous fish.
- This change in fish community leads to increase in large-bodied zooplankton, causing reduction in phytoplankton.
METU Limnology Lab Conducted First Biomanipulation Experiment in Turkey:
Basic Information About the Biomanipulation Experiment
Biomanipulation Experiment was conducted in Lake Eymir, ANKARA
•August 1998- December 1999
Fish Species that are Removed
– Tinca tinca
– Cyprinus carpio
•% 50 Reduction in Fish Stock
• Decrease in Chlorophyll-a and Suspended Solid Concentration
• Decrease in Nutrient Concentrations especially Phosphorus in parallel with increase in aquatic plant cover.