Chemostat Regulation Principles in Natural Plankton Communities

Abstract

Regulation of zooplankton population densities was shown in rotifer chemostats and in simulation models of chemostats (Chaps. 3.3, 5.1). The next paragraph demonstrates the utility of an experimental chemostat as a model ecosystem. In these models, zooplankton and phytoplankton are interrelated in a regulated cybernetic control loop. Can these models explain the regulation principles in the much more complicated plankton community, with many other species as competitors, predators, and food for rotifer and other zooplankton species (see Chap. 6.3)? This is a problem of scaling up the models and the experiments on the temporal and spatial scales (e.g., Frost et al. 1988). Chemostat work is surely a method at the level of laboratory experiments. It is a good technique to recognize causal relationships but requires an artificial system. These results must be extended to the much more complex lake. Upscaling has to follow hitherto not fully understood principles of similarities of structure (by dimensional analysis) and of function (Uhlmann 1985). This has been done by many aquatic ecologists from laboratory experiments to enclosures in lakes up to manipulations of whole lakes (see review of Lundgren 1985).