COMPARISONS, BY MODELS, OF SOME BASIC MECHANISMS ACTING ON THE DYNAMICS OF THE ZOOPLANKTON-TOXIC PHYTOPLANKTON SYSTEM

In this paper, classes of mathematical models of phytoplankton–zooplankton systems with toxic phytoplankton are proposed and analysed. We investigate various situations, by changing the uptake function, the mortality of the zooplankton or the toxin liberation process, and we compare the corresponding dynamics. We show notably that a stable oscillatory regime (after a Hopf bifurcation) can only be observed if the uptake function is nonlinear.