In the ponds of the "De Maten", two opposing forces are working in on local zooplankton community structure: on the one hand different local environmental factors in the ponds (local processes) lead to divergence of the zooplankton communities, while high dispersal rates (regional processes) tend to homogenize the connected zooplankton communities (i.e. a metacommunity) in different ponds. This study investigated whether these local and regional processes influence local zooplankton community structure, diversity and dynamics. Using both observational and experimental data, I could show that both processes do occur in the ponds of "De Maten", with local processes of primary importance. I found experimentally that local environmental variables related to alternative equilibria in shallow lakes (fish predation and macrophyte cover) quickly structured a community into four prototype communities: the combination of macrophyte-associated or pelagic species with predation sensitive (large) or small species. Three of the four prototype communities were described in the observational studies, and were also associated with fish predation, turbidity, chlorophyll-a, and macrophyte densities, explaining approximately 40 % of the variation in zooplankton community structure. I found that fish predation in the absence of macrophytes lowered the diversity considerably in the experiment. Observational evidence supports this, with high turbidity (corresponding to high fish predation in a shallow pond) associated with low diversity. Also regional processes structure zooplankton community structure. I found that directly connected ponds have more similar community structure than unconnected ponds. This spatial configuration explained approximately 15 % in zooplankton community variation. Also cladoceran diversity was related to the spatial configuration of the ponds, and was higher than in unconnected pond systems.

Next to these conceptual results, I also adressed three more technical (statistical) problems. I wrote a review on how to integrate space into ecological and genetic data analysis, in which I synthesized the possible methods and offered a logical framework. I also studied how lake area can influence the classical method to determine the relative importance of local and regional processes, i.e. saturation curves. I showed that include lake area in the construction of saturation curves resulted in small to medium sized lake determined by local processes, while larger lakes are determined by regional processes. I also discussed the use of the term pseudoreplication in large-scale experiments, prompted by an article of Oksanen (in Oikos 2001).

More information can be found on http://www.kuleuven.ac.be/bio/eco/Staff.php.