Macroinvertebrate Communities in a Lake of an Inter-Basin Water Transfer Project and Its Implications for Sustainable Management

In the present study, we choose the Weishan Lake, one of important water transfer and storage lakes on the eastern route of the South-to-North Water Diversion Project (SNWD) in China, to clarify how the community structure and assemblage-environment relationships of macroinvertebrates varied across three typical habitats (the River Mouth, Canal and Lake regions) over the four seasons in 2012. A total of 72 taxa belonging to 3 phyla, 9 classes and 24 families were recorded, with tolerant oligochaetes and chironomids as the dominant taxa. The environmental conditions and macroinvertebrate assemblages were clearly separated at spatial and temporal scales. Assemblage structure showed both significant but larger spatial than seasonal variations, with a clear separation of sites from three regions in an ordination plot. Compared to the temporal scale, more indicator species were retained to be responsible for the regional differences according to the two-way cluster analysis. Different environmental variables were significant for distinguishing macroinvertebrate assemblages among four seasons, and among them, pH was the only variable which was retained in all models. Our study provided useful background information of environmental characteristics and macroinvertebrate communities in a typical water transfer and storage lake before the water transfer of the SNWD. After the operation of SNWD, we envisage inter-basin water transfer (IBWT), which is usually accompanied by water level rise, nutrient pattern change and biota succession, will seriously affect recipient basins. Therefore, we propose several management strategies for SNWD: (1) target and detailed data should be collected on a timely basis: (2) government should prevent water pollution and adopt effective measures to protect the water environment: (3) the environmental assessments and other aspects of IBWT planning should be coordinated: (4) an overall consideration of different basins should be given to achieve a greater range of water resources planning, scheduling, and allocation: and (5) the migration and invasion of species should be of concern during the operation of the project.