A Simple Pelagic Ecosystem Model
(^) One of our basic goals in pelagic ecology is to understand at whatever level possible
the interactions among nutrient availability (a measure of the essential resource base),
phytoplankton growth (dependent upon species, nutrients, illumination, and
temperature), phytoplankton stock size (dependent upon growth, grazing, mixing, and
sinking) and zooplankton stock size (dependent upon grazing and mortality). The
most basic models are termed nutrient–phytoplankton–zooplankton, or NPZ, models.
An unrealistically simple, but instructive, version of an NPZ model was provided by
Franks et al. (1986). It examines the time course of quantities of dissolved nutrient
and assimilated nutrient (i.e. algal and herbivore biomass) in a theoretical upper water