Abstract
In Lake Nieuwe Meer near Amsterdam, the bloomforming cyanobacterium Microcystis aeruginosa dominates the phytoplankton in late summer and forms scums that can be a big nuisance. In Lake Nieuwe Meer the water column is stratified in summer. Microcystis can stay in the euphotic zone due to its buoyancy. Deep mixing of the lake abolishes this advantage of buoyancy of Microcystis and favours non-buoyant algae as they will have a reduced sedimentation loss.
The technique of artificial mixing has been applied in 1993 and 1994 applied in Lake Nieuwe Meer in order to reduce the growth of Microcystis. The application was successful: there has been no nuisance due to Microcystis scums. The percentage cyanobacteria of the total phytoplankton in summer decreased from ±90% without mixing to less than 5% with mixing. Characteristics of the equipment used for destratification are presented.
- Algal scums
- artificial mixing
- cyanobacteria
- eutrophication
- stratification
- © IWA Publishing 1995
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