Section Division of a Large River Main Stream Based on Bio-monitoring: A Case Study in the Dongjiang River, China

The benthic diatom community and environmental factors were investigated in Dongjiang River, China. Section division of the main stream was then conducted by using diatoms based on these investigations. The value of bio-monitoring is also discussed. According to the benthic diatom and environmental factor data on 40 sites, the main stream was divided into 4 sections by using several analysis methods (clustering, multidimensional scaling (MDS), and self-organizing map (SOM)). The results of canonical correspondence analysis (CCA) showed the existence of a phosphorus restriction for the diatom community in the mid and downstream sections, while the distribution of diatom was mainly influenced by dissolved oxygen, pH, and geographical factors. A Biological Diatom Index (IBD) was also calculated, and the results showed that this type of section division meets the requirement of ecosystem health management in Dongjiang River.