中文摘要：

为研究城市化对河流浮游细菌的影响，选取厦门后溪流域沿城乡梯度采集样品，并利用变性梯度凝胶电泳（Denaturing gradient gel electrophoresis，DGGE）和多元统计方法对浮游细菌群落空间分布格局进行分析. 结果表明，Shannon-Weiner多样性指数和DGGE条带数随着采样站点和城市中心距离的减小呈现先升高后下降的趋势. 聚类分析（Cluster）和多维尺度分析（Multidimensional scaling，MDS）将12个站点的浮游细菌群落分为4组，测序结果显示β-变形菌（Betaproteobacteria）是优势类群，占40.0%. 统计分析表明，pH和总氮（Total nitrogen，TN）是影响后溪浮游细菌群落组成最主要的环境因子，他们共同解释了47.6%的群落组成变化. 总之，沿城乡梯度随着水体理化指标的变化，浮游细菌群落也发生明显转变，表明后溪浮游细菌受到城市化的强烈影响. 此外，结果也提示DGGE可以作为监测与评价河流生态系统健康的重要工具. 图6 表2 参33

英文摘要：

To investigate the urbanization effect on riverine bacterioplankton, surface water samples were collected along an urban - rural gradient in the Houxi River Watershed, Xiamen, southeast China. Denaturing gradient gel electrophoresis （DGGE） and multivariable statistical approaches were used to characterize the spatial patterns of change in the bacterioplankton communities. The overall trend of Shannon-Weiner index and DGGE bands increased from site 1 to site 5 and then decreased from site 6 to site 12 with the decreasing distance between the sampling sites and downtown Xiamen. The cluster and multidimensional scaling analysis （MDS） resulted in four identical groups from the 12 sites, and Betaproteobacteria （40.0%） was the most dominant taxon derived from DGGE bands. Redundancy analysis （RDA） revealed that pH and total nitrogen （TN） were the main factors influencing bacterioplankton community composition in the Houxi River Watershed. Further, both pH and TN explained 47.6% of the variation in bacterioplankton community composition. In general, shifts in the bacterioplankton community were closely related to changes in environmental parameters along the urban - rural gradient, suggesting that the bacterioplankton assemblages of Houxi River Watershed were significantly influenced by Xiamen urbanization. In addition, the research data also suggested that PCR-DGGE could be used as an effective ecological indicator of riverine ecosystem health. Fig 6, Tab 2, Ref 33