Evaluation of the upper lakes of the Erhai watershed in China based on water quality, land cover, and macrobenthic invertebrates

In this study, three lakes, Cibi Hu, Haixi Hai, and Xi Hu, in the upper reaches of the main inflow rivers in the northern part of Erhai Lake were selected as the research objects. Based on the water environment monitoring indicators, land cover data, and lake macrobenthic community observation data, the non-parametric Kruskal-Wallis test, spatial analysis and community structure analysis were used to quantitatively assess the water environment and ecological status of the lakes. Using the Pollution Tolerance Index (PTI), the potential utility of macroinvertebrate communities as indicators of water ecological quality was investigated. The results showed that Cibi Hu and Haixi Hai have similar characteristics on water environmental quality. The physical and chemical indexes of water quality, the land cover of the lake catchment area, and the PTI index of the benthic community showed that Xi Hu was the most affected by human disturbance; the water ecological condition was the worst; and the environmental protection pressure was the greatest. In general, PTI analysis based on benthic fauna is convenient and can reflect the basic conditions of the aquatic benthic environment keenly, which is worthy of promotion.