Abstract:The effects of hydrology and nutrients (N and P) on the phytoplankton community were studied in the Dajingshan Reservoir belonging to a tropical zone during January to June in 2005. Seventy-six species of algae were identified. The total abundance of the phytoplankton ranged from 4.925×106 to 63.65×106 cells L-1and the total biomass from 1.632 to 20.420 mg L-1. Pseudanabaena sp. and Synedra ulna were dominant species in the community during January to March (the early spring). Only Pseudanabaena sp. was dominant during April to June (the late spring), and S.ulna decreased rapidly in number due to water temperature. The phytoplankton abundance in the late spring (April to June) was higher than that in the early spring, however, its biomass was reverse. The above results were attributed to the increase in water temperature, which was the most important factor for the change of species composition and phytoplankton dynamics. Pumped storage reservoir is a special type of water body, the phytoplankton community is regulated in a distinct way from that in the other reservoirs. Nutrient loads and hydrodynamic changes affected the composition and dynamics of the phytoplankton.
