Plankton is an integral part of wetland biodiversity and plays a vital role in the functioning of wetlands. Diversity patterns of plankton in wetlands and factors structuring its community composition are poorly understood, albeit important for identifying areas for restoration and conservation. Here we investigate patterns in local and regional plankton richness and taxonomic and functional community composition in riverine papyrus swamps, river mouth wetlands, and lacustrine wetlands in the Lake Tana sub-basin, Ethiopia. Data on phytoplankton, zooplankton, and environmental variables were collected from 12 wetlands during the dry and wet seasons of 2018. Redundancy analysis, and linear mixed effect models, were used to investigate differences in local environmental conditions and variation in plankton community richness and composition between wetland types. We also assessed the ecological uniqueness of the plankton community by calculating the contribution of a single wetland: local contributions to overall beta diversity (LCBD) and contributions of individual species (SCBD) to overall beta diversity (BDTotal). Beta regression models were used to investigate the relationships of LCBD and SCBD to environmental variables, wetland, and taxa characteristics. A total of 85 phytoplankton taxa, distributed among 18 Reynolds functional groups, and 57 zooplankton taxa were observed over the entire set of samples. Local plankton taxon richness was significantly higher in riverine papyrus swamps (mean taxa of 30 phytoplankton and 21 zooplankton) compared to river mouth wetlands (mean taxa of 27 phytoplankton and 13 zooplankton). Several local environmental variables and the composition of the plankton community differed significantly between the three wetland types. The highest phytoplankton ecological uniqueness (LCBD) was detected in lacustrine wetlands, whereas the riverine papyrus swamps had the highest zooplankton ecological uniqueness. Based on our analyses, we recommend protecting the wetlands with high LCBD values and stress the importance of various wetland types for preserving the diverse plankton communities of Lake Tana wetlands.

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The aquatic plants in wetlands have been threatened by increasing human disturbances in recent decades. The present study investigates to what extent human disturbance affects the community composition and richness of aquatic plants in 3 different wetland types in Lake Tana, Ethiopia. We selected twelve wetlands representing 3 different wetland types (four lacustrine, four river mouth, and four riverine papyrus wetlands) and collected data on aquatic plant species richness and community composition, major local environmental variables, and the degree of human disturbance at multiple plots along three transects in each wetland during the dry and wet season of 2018. The unique and shared contributions of human disturbance, local environmental variables, and wetland type on variations in community compositions of aquatic plants in wetlands were investigated using variation partitioning analyses. The Overlap and Decreasing Fill (NODF) metric was used to estimate the nestedness in aquatic plant communities. A total of 113 aquatic plant species, belonging to 38 families, were identified across all wetlands during the dry and wet season. Wetland types explained the greatest proportion of variation in community composition, followed by human disturbance and local environmental variables. The species richness was negatively correlated with the overall degree of human disturbance, while NODF was positively correlated. Irrespective of the degree of human disturbance, papyrus swamps had systematically the highest species richness and supported clearly different plant communities, therefore conservation efforts should focus on these habitats. In addition, measures should be taken to restore the highly disturbed and species-poor river mouth wetlands.