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UBC Theses and Dissertations

Modelling a two-species interaction in a high intertidal algal community Grabovac, Nickolas


This study is an approach to simulating the population dynamics and species interactions in an intertidal algal community. The community being modelled is located in Barkley Sound, Vancouver Island and consists of three dominant perennial macroalgae, Mazzaella cornucopiae, Fucus gardneri, and Pelvetiopsis limitata, as well as some ephemeral algae and invertebrates such as barnacles and limpets. Interactions between the two species Mazzaella and Fucus were simulated in order to predict their population dynamics over a two-year period. The empirical basis for the simulation models was provided by the field experiments and observations of previous researchers. In total, eight different models were created, six of them being cellular automata (CA) models and the remaining two being birth-death difference equation models. These models were tested and validated using an independent set of field data. In general, all of the models were. very poor predictors of Fucus density. Two of the models were excellent predictors of Mazzaella percent cover: a stochastic nonseasonal CA model and & Mazzaella birth-death model. The study suggests that simple, few-species models are able to predict the. dynamics of some species, even when such species interact with many other species in the community. In addition, this study serves as an example of how many of the problems associated with constructing mathematical models of ecological systems, especially CA models, can be overcome and how a greater understanding of the system of interest can be gleaned from their results.

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