Modelling the oceanic food web using a quasi steady-state approach

In aquatic food web models one is often interested in the long-term average (or expected) values of the model-outputs rather than the actual dynamical solution. In this paper an aquatic food web model is analysed by comparing a dynamical solution of the system equations with a quasi steady-state solution, which is defined as the series of (potential) steady states that correspond to the inputs and boundary conditions at each particular time. Although the system is never actually in (or even near) steady state, it appears that the yearly averaged values of the variables are similar for dynamical and quasi steady-state solutions. This conclusion is robust for a wide range of parameter values. A practical implication of this result is an increase in computational efficiency. A theoretical implication is that it shows the relevance of steady-state analysis, which may result in a considerable model simplification without appreciable loss in accuracy.