Eutrophication characteristics and distribution of phytoplankton communities in Liuduzhai reservoir in summer

Liuduzhai reservoir is an important back-up drinking water source of Shaoyang City,Hunan Province,China. In this study,various environmental parameters and phytoplankton composition were investigated in summer 2012,and eutrophication status of the reservoir was assessed. The results showed that TN and TP concentration was 0. 88 and 0. 04 mg·L-1respectively,which is relatively high. In some sampling points,TN and TP concentration exceeded grade Ⅲ of the ground water quality standard in China. Phytoplankton cell density was in the range of 3. 68 ×106~ 5. 84 ×106cells·L-1. Chlorophyta was the dominant alga in central area of the reservoir,and Cyanophyta was dominant alga near the dam area. Range of ShannonWiener index( H') was 2. 19 ~ 3. 17,Chlorophyll a concentration was 3. 64 ~ 20. 24 μg·L-1,and Topic Level Index( TLI) was 38.51 ~48.11. The result indicated that the reservoir was in meso-eutrophic state. In order to control eutrophication progress and prevent cyanobacterial bloom,long-term monitoring and integrated control of pollution were needed.