A COMPARATIVE-STUDY OF THE ECOSYSTEM DYNAMICS OF 4 FJORDS

In this paper we develop our previously published strategic simulation model of a sea-loch into a quantitatively testable form. This formulation includes the effects of phytoplankton self-shading, aggregation by zooplankton to areas of high phytoplankton density, and a representation of temperature-dependent energy allocation in zooplankton. We confront the model with datasets from four contrasting Scottish and Irish sea-lochs. After further extension to incorporate variations in the vertical distribution of phytoplankton, driven by vertical mixing and grazing pressure, the model provides a quantitatively acceptable fit to all four datasets. We illustrate the ''top-down'' nature of the control operating in these systems by formulating a three-state variable model, describing only the biotic components of the system. This simplified model produces the same quality of fit to the appropriate data as its progenitor.