On the stability of some equilibrium points in a plankton population model

It is proved that the equilibrium point (N₀, 0, 0) for the plankton population model given in Edwards and Brindley, (1996, Dynamics and Stability of Systems, 11(4): 347-370) is unstable in the case of two negative and one zero eigenvalues, thus correcting an assertion on its stability in the above quoted paper.