Microhabitat selection and diel patterns of zooplankton in a Mediterranean temporary pond

Abstract

Changes in zooplankton microhabitat use in lakes through diel migrations (vertical and horizontal) have been related to habitat heterogeneity and to predation pressure, among other factors. However, there is a controversy concerning the effectiveness of diel migrations in temporary ponds, due to the shallowness of these systems and their distinct aquatic predator communities (mainly macroinvertebrates and amphibians). In order to test if diel microhabitat selection patterns described from lakes hold in temporary ponds, we developed a study using funnel traps at different zones of the pond (high and low vegetation density; surface and bottom of the pond) that were checked during the day and at night. Additionally, we assessed predation risk by sampling the macroinvertebrate community at the same time. In the studied Mediterranean temporary pond, zooplankton exhibited diel patterns of microhabitat selection: cladocerans showed a diel horizontal pattern, whereas copepods showed a diel vertical pattern. Results suggest that microhabitat selection and the associated diel pattern may be explained by both biological (potential predation) and environmental drivers (habitat heterogeneity and protection against ultraviolet radiation).