Abstract
The preserved or vegetated aquatic plant community offers refugia for large-bodied zooplankters from their visual predators. A field investigation was carried out to examine the horizontal distribution of zooplankton in an artificial pond with a preserved emergent macrophyte community (Typha angustifolia) zone and an artificial embankment. The results reveal that density of large bodied-crustaceans were higher in the vegetation area. However, this phenomena was changed by various factors, e.g. species character and annual transience of emergent macrophytes. Large-bodied and limnetic species cladocera were favoured when macrophytes were well emerged. Littoral species cladocera could inhabit constantly in the vegetation, and distribution of cyclopoida differed with the developmental stage. Copepodid stages preferred to inhabit the vegetated area than open water and nauplius stages distributed with no relation to the vegetation during their high biomass season. These phenomena may be related to size selective and visual predation by planktivorous fishes. Overall to our study, the ponds with preserved emergent macrophyte communities could stock higher density of large-bodied crustaceans than plain ones. It is suggested that these zooplankters graze phytoplanton intensively and improve the water quality.
