Meta-population model of predator-prey mussel bed dynamics

A relatively recent theoretical development in ecology is the study of ecological dynamics on multiple scales.  The present study extends the one-bed population-scale model consisting of three coupled ordinary differential equations (ODE) for predator-prey mussel bed dynamics of intertidal mussel beds to a regional scale “metapopulation” of mussel beds linked by predation.  The initial model considered consists of two mussel beds linked by a common predator population.  The dynamics of the two-bed model were studied for varying levels of predation.  For very low levels of predation both mussel beds had a high biomass and for high levels of predation both mussel beds had a low biomass.  For intermediate values of predation there are multiple stable equilbria and the final state of the metapopulation will depend on initial conditions.  The two-bed metapopulation model was extended to any arbitrary number of metapopulation models.  The topological arrangement must be considered when modeling metapopulations of several mussel populations.  Two types are being studied: the harbor model and the coastal model.  The harbor model consists of n mussel beds which share a common pool of predators that move randomly among the mussel beds.  The coastal model consists of a linear array of n mussel beds which act as “stepping stones;” predators can move to and from adjacent mussel beds only.  Preliminary results on these complex metapopulation models will be presented.  Using a multi-scale spatial model will provide a better understanding the ecology of predator-prey dynamics at a regional scale and may suggest field experiments.