Effect of demographic noise in a phytoplankton-zooplankton model of bloom dynamics

TL;DR

This paper extends a phytoplankton-zooplankton model to include demographic noise, showing that fluctuations can induce bloom cycles and destabilize populations even in large water bodies.

Contribution

It introduces a demographic noise extension to the classical model, revealing new dynamics under seasonal forcing and shallow water conditions.

Findings

Demographic fluctuations can cause switching between bloom and no-bloom states.

Fluctuation-induced destabilization persists in large, infinitely extended water basins.

Seasonal forcing influences the impact of demographic noise on bloom dynamics.

Abstract

An extension of the Truscott-Brindley model (Bull. Math. Biol. {\bf 56}, 981 (1994)) is derived to account for the effect of demographic fluctuations. In the presence of seasonal forcing, and sufficiently shallow water conditions, the fluctuations induced by the discreteness of the zooplankton component appear sufficient to cause switching between the bloom and no-bloom cycle predicted at the mean-field level by the model.The destabilization persists in the thermodynamic limit of a water basin infinitely extended in the horizontal direction.