Biodiversity-oriented water ecological restoration effect in urban river with reclaimed water supply

The monitoring and analysis of water ecological restoration effects are useful to improve the ecosystem health of rivers replenished by reclaimed water. The water ecological restoration covering all trophic levels was conducted, and the community structure, biodiversity indices and water quality were monitored for one year to judge the change of ecosystem health in the old river section of Xiaotaihou River in Beijing. As the results showed, although both the water environmental quality and water quantity suffered great decreasing during the experiment, the water ecological health and water environmental quality in the experimental zone all improved. After ecological restoration, species richness of zooplankton, zoobenthos, fish and birds increased to 6, 2, 3 and 2 times of the previous, respectively. The numbers of dominant species of zooplankton, zoobenthos and fish all increased significantly and the dominant species changed from pollution-tolerant species to a health indicator type. Shannon-Wiener diversity index, Pielou evenness index and Margalef abundance index of zoobenthos, fish and bird all increased. The dominant bird species changed from season to season. The top species of the food chain appeared. The average contents of total phosphorus, ammonia nitrogen and total nitrogen in the experimental zone were 35%, 31% and 30%, respectively, lower than those outside the experimental zone. In a word, the water ecosystem with a complete structure could resist external disturbances such as water quantity and quality changes and improve water environmental quality. Biodiversity indexes and community structures of biological communities could respond and indicate the change of the water environment well. The comprehensive evaluation of multiple biodiversity indexes was more comprehensive and objective than the individual index.