Dynamic analysis of phytoplankton–zooplankton–fish singular perturbation system on three time-scales

In this paper, a three-time scale plankton–fish singular perturbation system is proposed by considering the Beddington–DeAngelis functional response and intraguild predation (IGP). For (1, 2)-fast–slow systems, the singularity and classification of generic fold points are discussed. The small amplitude oscillations (SAOs) will generate around the weak characteristic direction near the folded node, which provides a theoretical reference for effectively predicting the phenomenon of algal blooms. It is also obtained that the small amplitude oscillation cannot be generated by the singular Hopf bifurcation and the folded node mechanism. For (2, 1)-fast–slow systems, the existence of singular Hopf bifurcation is discussed by using the center manifold reduction method. The stability of the periodic solution of the singular Hopf bifurcation is discussed. Furthermore, the existence and uniqueness of the relaxation oscillation in R3 are researched by using the entry–exit function. In addition, the effect of stochastic factors on the singular perturbation system is considered.