Eutrophication is the most widely spread environmental disturbance in freshwater ecosystems. Eutrophication causes multiple changes in the physical-chemical conditions of lakes (turbidity nutrient concentrations, vertical oxygen profiles) with consequences for biotic communities. Numerous of our projects have been and are connected to the effects of eutrophication. For instance the effects of increasing turbidity and decreasing hypolimnetic oxygen concentrations on predator prey interactions have been studied in numerous field sampling campaigns and experiments. The effects of catchment land use on external P loading of lakes has also been included. The studies have been funded by the Academy of Finland, Maj and Tor Nessling Foundation, Lake Vesijärvi Foundation, the City of Lahti and Maa- ja Vesitekniikan tuki ry.