Comparison of the Phytoplankton Community in Major Rivers of the Taihu Basin
太湖流域主要河道浮游植物类群对比研究

Phytoplankton assemblages were sampled in spring (13th-22nd April) and summer (10th -19th July), 2010, and were compared in order to obtain basic information of the community of phytoplankton and their relationships with environmental factors among different rivers in the Taihu basin. Samples for phytoplankton were both identified and counted under a microscope at 400×. The results of counting shown that Synedra sp., Cryptomonas sp., Aulacoseira sp., Fragilaria sp. and Navicula sp. were the dominant genus in the inflowing rivers and Aulacoseira sp., Scenedesmu sp., Cryptomonas sp., Asterionella sp. and Closterium sp. in outflowing rivers in spring. And in summer, the major genus in inflowing rivers were Synedra sp., Crucigenia sp., Cryptomonas sp., Euglena and Microcystis sp. and were Aulacoseira sp., Scenedesmus sp., Cryptomonas sp., Synedra sp. in outflowing rivers. That is to say the phytoplankton community is different between both in temporal and spatial distribution in Taihu basin. Then several diversity indices were calculated and the indices shown that diversity of phytoplankton in spring were slightly higher than in summer, and it was also varied among rivers. Liner regressions between diversity indices and environmental factors indicated that Shannon-Wiener diversity index had strong relationships with conductivity, total phosphorus (TP), total nitrogen (TN), total solid suspended (SS), chemical oxygen demand (CODMn) and nitrate (NO3--N) in spring and nitrate (NO3--N), chemical oxygen demand (CODMn) conductivity in summer. Further more, the most important environmental factors that regulated the phytoplankton community (basically analyzed according to predominated genus) were SS, TN, and conductivity in spring, and were CODMn, NO3--N and TN in summer as illuminated by the ordination of Canonical correspondence analysis (CCA).