Environmental Impacts on Summer Phytoplankton Community Structure in Different Types of Bays,Taihu Lake
太湖夏季不同类型湖区浮游植物群落结构及环境解释

Phytoplankton community structures of 31 sites of grass-type bay and algae-type bay were investigated in Taihu Lake in September,2010.A total of 120 taxa were identified and most of them belong to Cyanophyta,Chlorophyta and Bacillariophyta.Microcystis spp.was the single dominant species in the two type bays,which lead to the decrease of community diversity indices.Canonical correspondence analysis was used to investigate the environment-phytoplankton relationship.Case ordination by CCA divided all sites into three groups,group I being grass rich area,group II being algae rich area and group III being Wuli Bay,respectively.Compared to algae-type bay,sites of grass-type bay showed three characteristics as follows: higher species number and diversity indices,lower algal density.Besides,the nutritive level of grass-type bay was lower and TP concentration significantly lower(t=-3.84,P=0.001) than algae-type bay.The Microcystis spp.quantity ascended as the suspended substance(SS) concentration increasing.Decreasing the SS and improving the water transparency would be the main goals of ecological restoration for Taihu Lake,which would lay a solid foundation for grass-type lakes in the future.