JOURNAL OF PLANKTON RESEARCH | VOLUME 12 | NUMBER 1 | PAGES 77-87 | 1990
© Oxford University Press
research-article |
Resource competition between two rotifer species (Brachionus rubens and B.calyciflorus): an experimental test of a mechanistic model
Department of Biological Sciences and Center for Great Lakes Studies, University of Wisconsin—Milwaukee Box 413, Milwaukee, WI53201 1Department of Biology, The Pennsylvania State University, University Park PA 16802, USA 2Deceased
Received on October 31, 1988; accepted on August 1, 1989 A mechanistic model of competition on a single resource was tested experimentally with two freshwater rotifers, Brachionus rubens and B.calyciflorus, both grown on the alga Chlorella pyrenoidosa. Using open culture systems for each species we measured: (i) the resource-saturated exponential growth rate, µmax, and (ii) the relationship between specific growth rate, µ, at steady-state and the residual algal concentration over a range of system turnover rates, or dilution rates, D. The µmax of B.calyciflorus was {small tilde}60% higher than B. rubens. These results were then used to construct a graphical model for predicting the victor in interspecific competition between the two rotifers. Since the two resource-dependent growth rates crossed, one species, B.calyciflorus, was predicted to be the victor at a high D while B. rubens was predicted as the victor at low D. Finally, the outcome of competition was determined for two turnover rates. As predicted by the graphical competition models, B.calyciflorus was the dominant species at rapid D (0.029 h–1) and B.rubens was dominant at slow D (0.0044 h–1). These studies support recent conclusions that mechanistic competition models may be applied to predict dominant species from a priori information on growth potential and resource levels, which is not possible with traditional Lotka-Volterra models.