| Water environmental variables and benthic macroinvertebrates of 29 stream sites were investigated in the middle section of Qiantang River Basin in April 2010. All sampling sites were plotted out reference, agriculture and urban groups by CLUSTER analysis, One-way ANOSIM showed a significant difference (r=0.863, P=0.001) between these three groups. Principal component ordination of environmental factors indicates the major stress is anthropogentic land use and the combined variations of water quality. The most important variables structuring macroinvertebrate assemblages were percentage of agricultural land use, percentage of urban, dissolved oxygen (DO), total nitrogen (TN) and the mean substrate score (Rho=0.568, P=0.001). Macroinvertebrate community structures and integrities were degraded and showed specific variation due to agricultural and urban land use based on macroinvertebrate metrics and k dominance curves. Moreover, agricultural sites were in a slightly more modified ecological state than urban sites overall. |
