stable - - - unstable A water cloudiness N nutrient level 0.5 a) If the nutrient level is 0.2, approximately what will the water turbidity level be? b) If the nutrient level then increases to 0.8, approximately what will the water turbidity level be? c) Suppose the nutrient level increases further, to 1.0. What will the water turbidity be? d) You are in charge of water quality for this lake. Your predecessor on the job decided that lowering nutrient levels to 0.8 would be sufficient to restore clear water. What happened to the water turbidity when this was done? Why? e) How low do nutrient levels need to be for the water to become clear again? f) The main source of nutrients in the lake is fertilizer washed off from local lawns and gardens. Although people want clear water, significantly reducing fertilizer use is not initially a popular proposal. Explain your nutrient reduction goal in a way community members can understand. Note: The phenomenon illustrated here, in which a change in state caused by a parameter change cannot be reversed by undoing the parameter change, is known as hysteresis. Scheffer et al. (2001) provides excellent explanations and examples