A simple theory of algal deposition

SUMMARY. A model describing the deposition of algae in a turbulent environment is outlined, it being assumed that all algae falling on the bed are trapped there forever. Its main features are that, above a certain threshold of turbulence the rate of deposition is independent of the turbulent intensity, and the rate of algal loss by sedimentation, in such conditions, is described by a first order kinetic equation. The hydraulic conditions under which algae settle at their intrinsic, still‐water rate and those for which the model is applicable, are examined. Some ecological implications of the model are discussed.