Seasonal Variation of Phytoplankton Community Structure in Hengshan Reservoir

As a large reservoir in Taihu basin,Hengshan Reservoir plays an important role in flood control and drinking water safety of Yixing City.In the present study,the seasonal variations of phytoplankton assemblages were investigated between 2010 and 2011.A total of 90 taxa were identified and most of them belonged to blue-green algae and diatom.Cylindrospermopsis sp.was the first time found in Taihu basin,which could induce algal bloom in summer with the density reached to 1.01×108 cells/L.More and more pollutants were flowed into Hengshan Reservoir in recent years,which lay the foundation for Cylindrospermopsis bloom.As an invasive cyanobacterium,Cylindrospermopsis can produce several toxins,which would be endangered to ecological system equilibrium and public healthy.Through regulating the nutrients concentrations and water level or hydraulic retention time in Hengshan Reservoir,Cylindrospermopsis blooming would be controlled.Meanwhile,we should increase monitoring frequency and strengthen management in order to prevent Cylindrospermopsis invading other large reservoirs of Taihu basin.