Dissolved organic carbon and relationship with bacterioplankton community composition in 3 lake regions of Lake Taihu, China.

To clarify the relationships between dissolved organic carbon (DOC) and bacterioplankton community composition (BCC), a 1-year survey (June 2009 - May 2010) was conducted in 3 regions of Lake Taihu (Meiliang Bay, Lake Center, and Eastern Taihu), China. Polymerase chain reaction - denaturing gradient gel electrophoresis was used to analyze the composition and heterogeneity of the bacterioplankton community. Canonical correspondence analysis was used to explore the relationships between DOC concentration and BCC. We found a significant negative correlation between DOC concentration and bacterioplankton community diversity (as measured by the Shannon-Wiener index (H')). The results show that spatial variation in the bacterioplankton population was stronger than the seasonal variation and that DOC concentration influences BCC in Lake Taihu. DOC concentration, followed by macrophyte biomass, water turbidity, and phytoplankton biomass were the most influential factors that account for BCC changes in Lake Taihu. More detailed studies on the relationship between DOC concentration and BCC should focus on differences in DOC concentrations and quality among these lake regions. DOC had a significant impact on BCC in Meiliang Bay. The relationship between DOC and BCC in the 2 other regions studied (Lake Center and Eastern Taihu) was weaker. The results of this study add to our understanding of the BCC in eutrophic lakes, especially regarding the role of the microbial loop in lake ecosystems.