Impact of habitat heterogeneity on the biodiversity and density of the zooplankton community in shallow wetlands (Upo wetlands, South Korea)

Macrophytes play a major role in the structuring of aquatic environments, and create diverse microhabitats. Therefore, these plants represent an important factor regulating the zooplankton biomass, taxonomic composition, and distribution in freshwater ecosystems. In the current study, we examined the effects of the structural heterogeneity provided by various macrophytes. We identified four habitat types in this study: (1) open water (without macrophytes), (2) the helophyte zone, (3) the pleustophyte zone, and (4) the mixed vegetation zone (containing pleustophytes, nymphaeids, and elodeids). We tested the hypothesis that complex habitat structures support large zooplankton assemblages. Specifically, we collected zooplankton samples from a total of 119 sampling points in the Upo Wetlands, South Korea, during the spring and autumn of 2009. The largest zooplankton assemblage was found in the mixed macrophyte zone, followed by the helophyte and pleustophyte zones. The pleustophyte zone supported larger zooplankton assemblages during autumn compared to spring. Differences in zooplankton assemblages were considered to be strongly related to seasonal variation in the development and growth of pleustophytes. However, two-way ANOVA revealed that seasons had no significant influence on the zooplankton density and diversity. Instead, different habitat types substantially determined zooplankton characteristics. In conclusion, we demonstrated that wetland areas with high macrophyte species diversity contribute toward higher zooplankton diversity.