Some plankton species like cyanobacteria have an advantage in the
competition for light over other because of their buoyancy. This advantage can be diminished by vertical turbulence in the surrounding water column. In this way turbulence can induce a switching between the dominant species in a pure competition model. Introducing a grazing predator, the system can show a range of different dynamics depending on the strength of turbulence. Using some approximations which allow to describe the influence of turbulence in a non-spacial model, it is shown that turbulence can be one mechanism of the abrupt change in the biological diversity in shallow lakes. In a diffusive coupled spacial model local turbulence can also have a global effect on the biological system.

Plankton; Competition; Predation; Turbulence; Partial Differential Equations