太湖浮游细菌与春末浮游藻类群落结构演替的相关分析

为研究浮游细菌与浮游藻类群落演替的相关性，2005年4月至6月在太湖5个观测点采集浮游细菌及浮游藻类样本。分别采用聚合酶链式反应-变性梯度凝胶电泳（PCR—DGGE）和显微观察的方法分析浮游细菌及浮游藻类群落组成。结果表明，春末夏初，浮游细菌与藻类均呈现较高的多样性，浮游细菌DGGE图谱具有43种不同条带，浮游藻类的常见种有29种。浮游细菌群落聚类分析显示，丝藻（Ulothrix sp．）和微囊藻（Microcystis spp．）占优势时，浮游细菌群落基因组成存在明显差异。以藻类种群Shannon—Wiener多样性指数（Hp），浮游藻类总细胞数（N）以及Microcystis spp．（M）百分含量为变量，典型对应分析（CCA）结果显示浮游细菌与浮游藻类群落结构变化的相关系数为30．9％，表明春末夏初太湖浮游细菌与浮游藻类群落演替具有较高的相关性。

Relationship between bacterioplankton and phytoplankton community dynamics during late spring and early summer in Lake Taihu

The relationship between bacterioplankton and phytoplankton community composition was investigated from April to June, 2005 with samples taken at five different stations in Lake Taihu. Bacterioplankton and phytoplankton community composition as determined by denaturing gradient gel electrophoresis of polymerase chain reaction amplified bacterial 16S rRNA gene fragments (PCR-DGGE) and microscopic examination respectively, revealed a high degree of diversity. In total, 43 unique bands were identified among those DGGE profiles, and 29 dominant phytoplankton populations were observed. The DGGE profiles were clustered into two distinct groups. These two clusters were closely associated with two dominant phytoplankton, Ulothrix sp. and Microcystis spp. as observed on April 19th and on May 27th and June 27th, respectively. The relationship between bacterioplankton and phytoplankton community composition was investigated using Canonical Correspondence Analysis (CCA) with Shannon-Wiener diversity index of phytoplankton community (Hp), total cell abundance of phytoplankton (N), and the relative abundance of Microcystis spp. (M) as the variables. The CCA results indicated a 30.9% correlation coefficient suggesting a high degree of correlation between bacterioplankton community composition and the phytoplankton community.