On the Emergent Properties of Marine Ecosystem Models

Abstract

In the context of marine ecosystem modelling an emergent property occurs when patterns or properties arise from the interaction of lower level properties, none of which exhibit it. This thesis takes a retrospective view of a series model studies to demonstrate the ability of the European Regional Seas Ecosystem Model (ERSEM) to produce emergent properties. The studies chosen fall into three main categories: emergent community structure in response to environmental forcing, community response the anthropogenic perturbation and whether the ecosystem can amplify a weak atmospheric signal. The model is found to demonstrate weak emergence in the sense of generating patterns at a higher lever of organisation (e.g. community structure, phytoplankton succession) generated by the underlying agents. However there is little evidence that intrinsic emergence is produced. The adequacy ERSEM and other current modelling approaches for creating emergence is discussed and suggestions made for new directions in which may better capture the emergent properties of marine ecosystems. It is suggested that more emphasise is placed on underlying mechanism of cell physiology and foodweb interactions and less on empirical or numerical parameter fitting. Ultimately there is a need to think differently and more creatively about how marine ecosystems are modelled