北运河水体浮游细菌群落的空间分布特征及其与水质的关系

污染源汇入和闸坝拦截等因素能够影响城市河流水生生态环境质量,主要表现在群落结构和功能的改变。分别于春季、夏季和冬季3个季节对北运河干流的10个点进行水样采集,通过16S rDNA末端限制性片段长度多态性(T-RFLP)分析手段研究了北运河河道水体浮游细菌的群落结构,以揭示流域微生物多样性以及浮游细菌群落与水质因子的响应关系。共得到47种不同的片段,其中218bp片段是优势菌。T-RFs片段计算微生物多样性指数和均匀度指数结果表明,目前北运河水体生态结构已经较为脆弱。冬季与其他季节的群落组成有明显差别,夏季细菌丰度高于冬季。通过CANOCO软件分析浮游细菌群落结构与水质指标的空间特点,发现水体流动性降低、支流汇入和污染源的汇入都会引起微生物群落结构在空间上的改变;环境因子与微生物群落组成的相关性研究表明,总磷、溶解性有机碳(DOC)和温度对北运河微生物群落结构影响较大。

Spatial Distribution of Planktonic Bacterial Community and Its Relationship to Water Quality in Beiyun River

Quality of aquatic ecosystem was affected by discharges of wastewater and river fragmentation, which can be assessed by structure and functions of planktonic bacterial community. In this paper, the composition of bacterial community in Beiyun River was assessed by techniques based on terminal restriction fragment length polymorphism(T-RFLP) and PCR amplified 16S rDNA fragment. Samples were obtained in winter and summer of 2010 and in spring of 2011. Microbial diversity in water and the relationship between phytoplankton bacterial community and water quality parameters were examined. A total of 47 fragments could be found, 218 bp fragment was the dominant bacterial in Beiyun River. Results on richness, diversity, and evenness calculated through T-RFs showed that the ecological status of Beiyun River was fragile. There were significant differences of bacterial communities among the summer, the autumn and the winter, which the richness in the summer was higher than that in the winter. Canonical correspondence analysis (CCA) obtained by CANOCO software indicated that the spatial distribution of the bacterial community was affected by flow rate, in-flows of tributaries, and discharges. Also, concentration of total phosphorus, dissolved organic carbon and temperature were key to the bacterial community.