中文摘要：

2004年4、8、10月及2005年1月调查结果显示，乌梁素海共有浮游植物7门58属，其中：绿藻门最多，共有22属；硅藻门次之，为14属；蓝藻门也较多，达到了13属；裸藻门、隐藻门及金藻门数量很少，分别为4属、2属和2属；甲藻门最少，仅有1属。全年以绿藻、蓝藻及硅藻为优势种属。浮游植物全年平均密度为33．01×10^4ind·L^-1，平均生物量为26．33mg·L^-1。随着季节的变化，各藻类密度及生物量变化幅度很大，春夏高，秋冬低。另外，根据PCQ评价模型计算结果可知，乌梁素海水体处于富营养状态。

英文摘要：

A survey concerning phytoplankton and nutritional levels in Lake Wuliangsuhai was continuously conducted in April, August, October 2004 and January 2005, respectively. The results showed that there are 58 genera phytoplankton, belong to 7 phyla in the Lake. Chlorphyta account for the most genera and bacillariophyta take the next, with 22 and 14 genera, respectively. Cyanophyta also represent 13 genera, while euglenophyta, eryptophyta and ehrysophyta have fewer genus with 4, 2 and 2 genera, respectively. Pyrrophyta has the least genera with only 1 genus. Chlorphyta, eyanophyta and baeillariophyta are the dominant phytoplankton through the year. The average density and biomass of phytoplankton were found to be 33.01 × 10^6 ind · L^-1 and 26.33 mg· L^-1 , respectively. The density and biomass of each algae alter with seasonal variation with high values in spring and summer and low values in fall and winter. In addition, the nutritional levels of Lake Wuliangsuhai were in eutrophication according to the result of PCQ model.