Experiments with multi-species communities are essential in order to get more insight in the complex interactions between organisms and their biotic and abiotic environment. The Limnotrons are aquatic model ecosystems that have been developed at the NIOO-KNAW Centre for Limnology to study pelagic community dynamics. They are suitable for the controlled study of multi-species interactions at larger spatial and temporal scales. The Limnotrons do not mimic any particular ecosystem, but should be used for the exploration of basic ecological principles. The temperature and mixing conditions in the Limnotrons can be set within narrow limits, whereas light conditions at the water surface are fixed. We show some results of system performance: mixing time, temperature control, light quantity and quality and development of a Cladocera community in a prototype of the Limnotrons. We provide results of an experiment done in four Limnotrons with the chlorophyte Scenedesmus obliquus. All trophic levels (decomposers, primary producers, and secondary producers) could be maintained in the Limnotrons for at least several weeks. Both abiotic and biotic data from the phytoplankton experiment show remarkably similar patterns through time, but had too low statistical power to prove that they are identical. We calculated the numbers of samples required for sufficient power for biomass data from two plankton experiments, and calculate required effect sizes for certain powers for a future set-up with 2×4 Limnotrons. We show that the power of the data is dependent on: the number of samples, the sample volume, the choice of the measurement method and the type of data transformation [KEYWORDS: Community, food web, plankton, cosm, Limnotron, power analysis]
Original languageEnglish
Journal publication date2003

ID: 170890