MODEL SIMULATIONS OF CONTINUOUS ROTIFER CULTURES

Derived from the Monod-model and regulating principles a regulation mo del of the rotifer development in chemostats was developed. The model was validated in continuous cultures of Brachionus angularis both in s teady-states, when undisturbed, and in transient-states after perturba tions by step changes of dilution rate or input substrate concentratio n. Simulations of the simple model monotonically approached steady-sta tes, but cultures show overshoots and damped oscillations before reach ing this state. After introducing time-lags into the model it depends on the size of the time lag if model rotifer densities reach stable st eady-state values (at low time lags) or stable limit cycles with perio dic oscillations (at high time lags). At even higher time lags chaotic conditions occur in the model with final extinction of the rotifers.