中文摘要：

为了解三峡水库在蓄水后底栖动物的群落结构特征,探索水文情势改变对底栖动物群落结构的影响,于2012年8月、11月及2013年4月对三峡水库的秭归、巫山、云阳、忠县和木洞五个断面底栖动物的群落结构进行了调查分析。结果表明：（1）共记录底栖动物43个属种,木洞种类最多（29种）,秭归最少（12种）。优势种为多足摇蚊（Polypedilum sp.）、前突摇蚊（Procladius sp.）、肥满仙女虫（Nais inflata）、霍甫水丝蚓（Limnodrilus hoffmeisteri）和一种钩虾（Gammaridae）;（2）在空间分布上,密度以木洞最高[（8180±2740）ind./m2],忠县最低[（116±42）ind./m2];生物量以木洞最高[（8.66±3.65）g/m2],云阳最低[（0.17±0.06）g/m2];（3）在季节动态上,密度以秋季最高[（3140±1450）ind./m2],夏季最低[（115±37）ind./m2];生物量则以春季最高[（3.83±2.11）g/m2],夏季最低[（0.65±0.46）g/m2];（4）底栖动物密度和生物量随着水深的增加呈下降趋势,在水深小于20 m的浅水区递减率最大;（5）丰度/生物量比较曲线（ABC曲线）分析显示,巫山属于中等干扰条件下的群落结构（W=–0.003）,而木洞属于严重干扰条件下的群落结构（W=–0.101）;（6）与建坝前相比,三峡水库底栖动物密度和生物量趋于减少。流速减缓、水深增加、水位波幅加大和沉积物中营养盐的升高可能是造成三峡水库底栖动物群落结构改变的主要因素。

英文摘要：

To understand the community structure of zoobenthos and their responses to hydrological alterations, we conducted a preliminary study at five locations of the Three Gorges Reservoir in August and November of 2012 and April of 2013. The results were： （1） A total of 43 species were identified. The richness of species was the highest in Mudong （29 species）, and the lowest in Zigui （12 species）. The dominant species were Polypedilum sp., Procladius sp., Nais inflata, Limnodrilus hoffrneisteri and one species of Gammaridae. （2） In terms of spatial distribution, the density of zoobenthos was the highest in Mudong [（8180±2740） ind. /m2] and the lowest in Zhongxian [（116±42） ind. /m2]. The biomass was also the highest in Mudong [（8.66±3.65） g/m2], and the lowest in Zhongxian [（0.17±0.06） g/m2]. （3） As for the seasonal variation, the density of zoobenthos was the highest in autumn [（3140±1450） ind. /m2] and the lowest in summer [（115±37） ind./m2]. The biomass showed a different seasonal pattern, which was the highest in spring [（3.83± 2.11） g/m2] and the lowest in summer [（0.65±0.46） g/m2]. （4） Both the density and the biomass declined along with the increase of water depth, and the decline rate was the highest in shallow areas （water depth 〈 20 m）. （5） The analysis of ABC curves indicated that the zoobenthic community in Mudong was most disturbed （W=-0.101）, followed by Wushan （W=-0.003） and others. （6） There was a trend of decrease in the biomass and the density of zoobenthos after the im- poundment of Three Gorges Reservoir. It is likely that the major factors affecting zoobenthos were the slower flow rate, the increase of water depth, the higher fluctuation amplitude of the water level, and the elevated nutrients in the sedi- ment after the impoundment of the Three Gorges Reservoir.