Size-structure dynamics of the rotifer chemostat: a simple physiologically structured model

The classical chemostat models of Monod and others were designed for unicellular organisms. We summarize evidence that these models are not adequate for the rotifer chemostat, then propose a new, physiologically structured model that resolves some of their key problems yet remains biologically simple. The new model includes separate ontogenetic stages for eggs and free-swimming rotifers, with generalized age structure in the egg stage and body mass structure in the free-swimming stage. We present several numerical examples to illustrate the model's behavior, and we compare these in a preliminary way with experimental evidence from the literature.