中文摘要：

于2007—2008年溪源水库蓄水前,2014—2015年溪源水库蓄水后对溪源宫水源地水体进行采样,分析了冬春季水体的理化指标、浮游植物生物量及群落组成。蓄水前共鉴定出浮游植物6门26属43种,水体水质状况较好,浮游植物细胞密度平均为7.31×10^5cells/L,以硅藻、绿藻门为优势门类,两者占浮游植物总生物量的比例约为54.7%、32.2%,水体呈贫-中营养状态。蓄水后,水体氮、磷营养盐浓度分别约为蓄水前的2.4倍、3倍,浮游植物细胞密度平均为1.42×10^7cells/L,约为蓄水前的20倍,且群落结构发生改变,优势门类为硅藻、蓝藻、绿藻,所占比例分别为40.2%、38.7%、14.4%,蓝藻门比例有显著提高,约为蓄水前的5倍。说明建库蓄水对浮游植物的影响显著。

英文摘要：

Study on the phytoplankton communities and water quality in Xiyuan River was carried out before（ 2007—2008） and after（ 2014—2015） the impoundment of Xiyuan reservoir. Based on the collected data, the physico-chemical indexes,phytoplankton communities in winter and spring were recorded and analyzed. In total,6 Phyla,26 genera and 43 phytoplankton species were observed in Xiyuan river before impoundment. In sampling section which was located in upper reach of Xiyuangong water uptake,the water quality was good,the average cell count of phytoplankton was 7. 31 × 10^5 cells / L. Meanwhile,phytoplankton was dominated by diatom and chlorophyta,accounted for 54. 7% and 32. 2% of the total phytoplankton biomass,respectively. And the trophic state was oligo-mestrophic. After impoundment,the concentration of TN,TP was respectively 2. 4times and 3 times more than before,and the phytoplankton biomass was higher,the cell count of phytoplankton was 14. 19 × 10^6 cells / L,which was about 20 times more than before. Then the phytoplankton community changed to be dominated by diatom,cyanophyta and chlorophyta, which accounted for 40. 2%,38. 7% and 14. 4%. The proportion of cyanophyta increased significantly to 5 times more than before, and the proportion of chlorophyta decreased. The impact of impoundment on phytoplankton communities was significant. This study provide reference for sustainable management of building dams in river.