The Role of Environmental and Spatial Processes in Structuring Stream Macroinvertebrates Communities in a Large River Basin

Abstract

Understanding spatial patterns of stream biological communities is important for stream ecosystem management. The questions which variables (spatial variables vs. environmental variables) are driving stream community structure, and whether stream network configuration could influence spatial patterns of the structure, are less investigated. We used stream macroinvertebrates community and environmental data collected from 142 sites in August 2010 across the Huai River basin, China, to answer these questions. Spatial variables were constructed based on symmetrical Euclidean distance and stream distance by using Moran's eigenvector maps. We evaluated the relative impacts of local environmental (physicochemical variables) and spatial (generated by overland and watercourse distances among sites) variables on the structure of macroinvertebrates using variation partitioning methods. Our results showed that both space and environment had significant effects on macroinvertebrates community composition, and the former explained more variations. Moreover, spatial variables based on the watercourse distance captured slightly more variation of macroinvertebrates community in stream networks than those derived from the overland distance.