Community Characteristics of Phytoplankton in Ecological Restoration of Rural Polluted Rivers

The T-type submerged dam based on zeolite and ecological floating bed was set up in Zhujiabang River, a tributary of the Zhihugang River(north of the Taihu Lake), together with ecological restoration measures such as aeration and slope wetland. From the perspective of phytoplankton community, the restorative effect of ecological restoration project on rural contaminated rivers was investigated. The results showed that(i) ecological restoration changed the community structure and succession tendency of phytoplankton, the dominant state of Cyanophyta and Cryptophyta was replaced by some species of Bacillariophyta, Chlorophyta and Pyrrophyta;(ii) ecological engineering restrained the standing stock of phytoplankton community greatly, total biomass of phytoplankton during the restoration period was less than 6 mg/L;(iii) biodiversity of phytoplankton during the ecological restoration maintained at a higher level(mean Shannon-Weiner index was 2.32). Considering the correlation between efficiency of ecological restoration project in purifying water, standing stock of phytoplankton and nutrient level of water, removal of nutrients by ecological restoration project was one of the major factors triggering the change of phytoplankton community characteristics.