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

The relationship between bacterioplankton and phytoplankton community compositions was investigated from April to June, 2005 with samples taken at five different stations in Lake Taihu, China. Bacterioplankton and phytoplankton community compositions 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 amongst the 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 phytoplanktons, Ulothrix sp. and Microcystis spp., as observed on April 19, May 27 and June 27, 2005, respectively. The relationship between bacterioplankton and phytoplankton community compositions was investigated using Canonical Correspondence Analysis (CCA) with the Shannon-Wiener diversity index of phytoplankton community (H_p), the 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 and phytoplankton community compositions.