太湖夏季不同类型湖区浮游植物群落结构及环境解释

2010年9月对太湖不同类型湖区31个站点的浮游植物群落结构进行了调查。结果表明,共检测到120种浮游植物,蓝藻门、绿藻门和硅藻门物种占据了相当大的比例。所有站点都有微囊藻出现,微囊藻是草型湖区和藻型湖区的数量单一优势种,导致31个站点的群落多样性指数值都较低。在环境变量的作用下,31个站点被分为3种类型,即草型湖区(组Ⅰ)、藻型湖区(组Ⅱ)和五里湖(组Ⅲ)。草型湖区物种数和多样性指数较高、浮游植物密度和营养盐浓度较低,总磷(TP)浓度极显著低于藻型湖区(t=-3.84,P=0.001)。在一定浓度范围内,微囊藻密度随着悬浮物(SS)浓度的增大而上升。太湖生态修复应以降低水体悬浮物浓度、提高水体透明度为目标,为草型湖泊生态系统的培植创造条件。

Environmental Impacts on Summer Phytoplankton Community Structure in Different Types of Bays,Taihu Lake

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.