Principles and approach for lake ecological restoration

Lake pollution and eutrophication have become an important issue in China.Re-establishing macrophyte dominance is thought to be an effective method for eutrophication control and improving water clarity.To date,few cases of lake restoration have been successfully implemented in China.One reason is that lake restoration is often limited to aquatic vegetation planting,and changes in environmental conditions were not evaluated and implemented.Lake restoration practices emphasizing macrophyte restoration without fully understanding relationships between macrophyte growth and environmental conditions are incomplete and short-sighted.In fact,lake ecological restoration requires knowledge of existing environmental conditions.If environmental conditions determine the ecosystem type,then changes in environmental conditions should be emphasized for understanding ecosystem shifts.For a lake ecosystem shift from algal-to macrophyte-dominated systems,these environmental conditions include weak wind-induced waves,high transparency,low nutrient loadings,a decrease in plankti-benthivorous fish and increase in predatory fish,removal of organic-rich sediment,etc.Lake macrophyte restoration is seldom successful when nutrient loading is still high.Therefore,lake restoration must be conducted subsequent to control of nutrient loading,i.e.control the input of pollutant first,then attempt ecological restoration.