滇池浮游细菌群落组成的空间分布特征及其与环境因子的关系

The spatial variations of bacterioplankton community composition in Lake Dianchi and their relation to environmental factors

为探讨滇池湖体浮游细菌群落组成的空间分布特征,并找出影响浮游细菌群落组成分布的主要影响因子,通过16S rRNA末端限制性片段长度多态性(T-RFLP)分析手段研究了滇池湖体夏季由北向南9个采样点浮游细菌的群落结构.结果表明,9个采样点共得到52个不同的片段(T-RFs),且每种片段至少代表一种细菌.各采样点浮游细菌群落的组成不同,并且优势菌也发生了变化,但9个采样点的Shannon-Weiner指数和均匀度指数都较低,说明滇池的生态环境已很脆弱.通过聚类(Cluster)和多维尺度(MDS)分析浮游细菌群落的空间分布发现,水质情况相似的采样点其浮游细菌群落组成也相似,并且可将9个采样点的浮游细菌群落组成分为4类.典型相应分析(CCA)结果表明,氨氮(NH4+-N)、总氮(TN)、硝氮(NO3-N)、叶绿素a(Chla)对浮游细菌的分布影响最大,其次为pH和温度.

Lake Dianchi is in a serious eutrophication state. However,the water quality varies spatially in the lake. In order to explore the spatial distribution of bacterioplankton community compositions （BCCs）,as well as to identify the key factors that affect the distribution of BCCs,9 surface water samples were investigated along the trophic gradient in the summer of 2009 by terminal restriction fragment length polymorphism （T-RFLP）. In total,fifty-two terminal restriction fragments （T-RFs） were detected in all samples. The nine samples had different bacterial compositions and predominant types. But the Shannon-Weiner diversity indices and evenness in all the samples were low,which indicated that the ecological status of Lake Dianchi was fragile. Multidimensional scaling （MDS） analysis indicated that the samples that scattered closely had similar water qualities,verified by cluster analysis using UPGMA （unweighted pair-group method using averages）. Meanwhile,the BBCs of 9 samples could be divided into four clusters. The result of canonical corresponding analysis （CCA） also illuminated the environmental factors affecting the BCC,among which NH4^＋-N,total nitrogen,NO3^--N and Chla were the most influential factors,though,pH and temperature also had a certain influence.