Effect of cascade hydro-electric stations on phytoplankton in Wujiang Watershed.

This paper reports a preliminary investigation in Wujiang Watershed focusing on the aquatic ecological impact of the existing five cascade reservoirs. Results shows that,in the general,phytoplankton species increase in the upstream inflows to the dams,among which Chlorophyta and Cyanophyta increase considerably,with Bacillariophyta remaining the major species in the reservoirs. The density and quantity of phytoplankton in reservoirs are 2.06 times and 1.77 times respectively higher than those in the inflows. Data of the daily-regulation type reservoir such as Suofengying Reservoir shows that the level of phytoplankton increase is relatively low compared with the annual-regulation reservoirs like Hongjiadu Reservoir. Other factors are involved with the nutrition loading and surrounding environment of the reservoirs.