Aggregation of toxin producing phytoplankton acts as a defense mechanism-- a model based study

We propose a simple model of toxin producing phytoplankton-zooplankton interactions in which the former is assumed to be able to detect the presence of zooplankton and to counteract it by forming colonies or patches and by releasing some toxic chemicals in the surrounding water. We observe that the formation of patch by the toxin producing phytoplankton decreases the grazing pressure of zooplankton resulting in stronger coupling between the interacting species determined by the fraction of the phytoplankton population that aggregates to form patches.