Assessment of water quality using benthic diatom and macroinvertebrate assemblages: A case study in an East China canal

The East Zhejiang Canal is an artificial waterway located in the plains of East China. Because of its role in providing social services, it is frequently subjected to human activities affecting its health. To improve the water resource management and condition of this canal, assessment of its ecological health is necessary. We measured water quality variables and benthic diatom and macroinvertebrate assemblages to evaluate the ecological status of the canal. We found that the canal was eutrophic with an average chemical trophic level index of 64.3 and an average trophic diatom index of 68.1 (with Nitzschia palea, Melosira varians, and Navicula rostellata, Encyonema minutum abundant). Macroinvertebrate assemblages also showed that the canal was eutrophic based on the dominance of Limnodrilus sp. A low BMWP (Biological Monitoring Working Party) score further indicated the poor water quality of the canal. Correlation analysis indicated that phosphorus was the main driver of eutrophication in the canal. Consequently, more attention should be paid to reduced phosphorus loadings.