A nutrient-prey-predator model with intratrophic predation

A simple food chain which consists of nutrient, prey and predator with intratrophic predation of the predator is proposed and analyzed. The dynamics of the model depend on the basic reproductive numbers of the prey and predator. Intratrophic predation can have impact on the system only if the basic reproductive number of the predator is greater than 1. In this case, the system may have multiple coexisting equilibria. However, intratrophic predation can stabilize the system when such an equilibrium is unique. Moreover, it can elevate the magnitude of the prey population and diminish the level of nutrient concentration of any coexisting equilibrium. (C) 2002 Elsevier Science Inc. All rights reserved.