JPR Advance Access originally published online on June 21, 2009
Journal of Plankton Research 2009 31(9):939-963; doi:10.1093/plankt/fbp042
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Parameterizing plankton functional type models: insights from a dynamical systems perspective
1 Centre for Environmental Systems Research, Griffith School of Environment, Griffith University, Nathan, QLD 4111, Australia 2 Mathematical Institute, University of Oxford, 24-29 St Giles, Oxford OX1 3LB, UK
* CORRESPONDING AUTHOR: r.cropp{at}griffith.edu.au
Received on March 31, 2009; accepted on May 22, 2009
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Abstract |
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The spectre of anthropogenic global climate change has focused attention on biogeochemical cycling in the oceans as marine plankton ecosystems are involved in the cycling of several compounds thought to have significant implications for climate. To better understand these processes, modellers are developing plankton functional type (PFT) models that group plankton according to their biogeochemical properties. There is some debate as to whether our understanding of plankton ecosystems is sufficiently well developed for PFT models to be reliable and for their predictions to be treated with confidence. In this paper, we examine the dynamical properties of a generic predator–prey–prey PFT model, then apply these analysis techniques to a simple example PFT model with two phytoplankton and one zooplankton in order to explore its parameter space. We find that parameter combinations for which all PFTs stay extant for all time appear rare, but develop a simple heuristic that allows such parameter sets to be identified relatively easily for many PFT models. We observe that such systems often have phytoplankton with similar growth rates, but that differ in other properties such as differing nutrient utilization strategies or different susceptibilities to grazing. We also note that persistent PFT systems are more likely if neither phytoplankton have a low specific mortality rate or is a highly nutritious food for the grazer.
Corresponding editor: Roger Harris