Clearing lakes : an ecosystem approach to the restoration and management of shallow lakes in the Netherlands

Eutrophication of lakes is a major problem for water management in the Netherlands. Lake restoration has been focused on the control of external P loading from point sources. However, this approach did not result in the water quality desired. The algae-dominated turbid water state may be extremely stable, and then additional measures are necessary to remove cetain "blockages" such as: the persistent bloom of Oscillatoria algae, the bloommediated P release from the sediments, and the abundance of fish, preventing zooplankton and submerged macrophytes from developing. This thesis addresses: - the lake conditions prior to disturbance, - the relationships between nutrient loading and lake response, - the control of P release from the sediments and Oscillatoria blooms by lake flushing and, the perspectives of fish stock management for the restoration of shallow lakes.