Intra-habitat heterogeneity of environmental factors regulating bacterioplankton community composition in Lake Taihu, China

Abstract

To investigate the intra-habitat heterogeneity of environmental factors that may have an impact on the bacterioplankton community composition (BCC), a 1 yr observation was done at 2 study sites in Lake Taihu, a large shallow eutrophic lake in China. One site was located at the center of Meiliang Bay, the other site was near the central region of the lake. Denaturing gradient gel elec- trophoresis (DGGE) of PCR-amplified partial 16S rRNA gene fragments was applied to analyze BCC. The unweighted pair group method with arithmetic mean (UPGMA) was used to investigate differ- ences among BCC. Redundancy analyses (RDA) of the gel patterns, in relation to the physical, chem- ical, and biological factors of the 2 sites, were performed. Differences between the samples in Mei- liang Bay and the lake center were evident during all periods. Four variables (the biomass of Microcystis spp., chl a, dissolved inorganic phosphorus (DIP), and water turbidity) were most strongly correlated with the bacterioplankton DGGE patterns. Particularly, significant intra-habitat hetero- geneity of the environmental factors was detected. In Meiliang Bay, seasonal variations in DIP con- centration had a profound impact on the composition of bacterioplankton communities, while in the lake center, wind-induced frequent sediment resuspension was an important reason for the varia- tions in BCC. The inherent intra-habitat heterogeneity of environmental conditions is essential to maintain the heterogeneity of BCC at the 2 study sites.