Spatio-temporal variations of the bacterioplankton community composition in Chaohu Lake, China

Despite considerable attention paid to Chaohu Lake in China, the dynamics of bacterioplankton community composition (BCC) on spatial and seasonal scales are poorly understood. In this study, water samples were collected from autumn 2006 to summer 2007 at five positions in Chaohu Lake with different trophic status. BCC of these samples was determined by both the PCR amplification of the 16S rDNA gene and the denaturing gradient gel electrophoresis (DGGE). The abundance and diversity of bacterioplankton communities at different sampling positions showed similar seasonal patterns. The BCCs in the samples varied substantially, and the pattern of changes indicated that the seasonal difference might have a significant impact on the BCC’s structure in the lake. Canonical correspondence analysis (CCA) on the DGGE patterns and physicochemical parameters indicated that the temperature and the levels of 5-d biochemical O2 demand (BOD5), NH3–N, CODMn, total nitrogen, total phosphorous, and dissolved oxygen significantly influenced the BCC, and four of the seven variables were related to the level of eutrophication. Our results indicate that eutrophic status and season are the most influential factors in determining BCC in Chaohu Lake.