中文摘要：

为了解湘江干流水质与生物群落现状, 2010-2011年对湘江的水质和浮游生物的分布进行了采样分析, 利用香农-威纳多样性指数分析湘江干流浮游生物群落特征, 并结合水质理化指标评价其水体营养状态。结果表明, 共检出浮游植物8门99属164种, 丰度变化在（1.83-51.1）×104cells/L, 生物量变化在0.03-0.60 mg/L; 浮游动物80种, 密度变化在2.16-76.34个/L, 生物量变化在0.01-1.95 mg/L。各采样点的浮游植物多样性指数变化在2.47-5.43, 浮游动物多样性指数变化在1.63-3.38, 浮游生物的多样性较好, 显示出湘江干流的浮游生物群落处于较稳定的状态。对湘江βm-αm指示种种类组成和群落结构分析, 结果显示湘江水体属于中污带水质; 综合营养状态指数（TIL）在38.27-51.97, 均值为43.73, 属于中营养水平; 综合水质生物学和化学评价结果可知湘江干流的水质较差, 但无明显向富营养化转化的趋势。

英文摘要：

To evaluate tropic state and biotic community of the main stream of Xiangjiang River, the water quality and plankton distribution were sampled and analyzed from 2010 to 2011. The plankton community characteristics of Xiangjiang River were studied via Shannon-Wiener index, and nutrient level was assessed in association with physicochemical index of water quality. The results showed that, a total of 164 species of the phytoplankton belonged to 99 genus; the total cell density varied from 1.83×104 to 51.1×104 cells/L; the biomass ranged from 0.03 to 0.60 mg/L. The species of zooplankton was 80 species, and the average abundance varied from 2.16 to 76.34 ind./L; the biomass ranged from 0.01 to 1.95 mg/L. The phytoplankton diversity index were 2.47-5.43, while the zooplankton ones were 1.63-3.38. The plankton diversity showed that the plankton community of Xiangjiang River in a stable state. From the analysis of the species and community composition of the βm-αm indicated species, it was found that the water quality of the Xiangjiang River belonged to the ecological middling pollution type. According to the comprehensive trophic level index （TLI）, the values of Xiangjiang River were between 38.27 to 51.97, and the average was 43.73. It showed that the river was in a mesotrophic level. The results showed that the water quality of Xiangjiang River is bad, but has no obvious trend to the eutrophication by chemical and biochemical evaluation.