Recurring plankton bloom dynamics modeled via toxin-producing phytoplankton.

A simple nutrient-phytoplankton model is proposed and analyzed in the presence of toxic chemicals released by toxin-producing phytoplankton (TPP) to understand the dynamics of seasonally recurring bloom phenomena. We observe that the presence of toxic chemicals helps to explain the bloom phenomenon. We have further studied our proposed system by varying the toxin liberation rate. Our model displays a wide range of dynamical behaviours, from simple cyclical blooms to irregular chaotic blooms. We also observe skipping phenomenon. The effect of toxic chemicals released by TPP cannot, thus, be ignored in 'bottom-up' models.