Abstract: This paper demonstrates the global existence and boundedness of the solutions of a toxic- phytoplankton-zooplankton model with chemotaxis and Allee effects in a smooth bounded domian with no-flux boundary condition. This result holds for arbitrary spatial dimension and small chemotaxis coefficients. It is also proved that the positive homogeneous steady state loses its stability when the chemotactic coefficient surpasses a threshold value, and the nonhomogeneous steady states bifurcate from the homogeneous steady state. Finally a numerical simulation is performed.

Key words: Chemotaxis, Toxic phytoplankton, Zooplankton, Allee effec