DEPARTMENT OF BIOLOGYMETU LIMNOLOGY LABORATORY


Biomanipulation

Eutrophication

•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.

 

Restoration Techniques:


•Reduced external loading
•Biomanipulation
- 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. 


Biomanipulation:



 

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.