Effects of Heavy Metal and Nutrients on Benthic Microbial Communities in Freshwater Sediment of Poyang Lake (China)

The aim of this work was to relate sediment microbial communities with geochemical processes in a freshwater lake. Surface sediment samples were collected from seven sites (i.e., main basin and tributary estuaries of the lake) at Poyang Lake, China in May of 2011. Sediment environmental parameters such as concentration of nutrients and total contents of heavy metals (copper, zinc, lead, and cadmium) were measured. Profiles of bacterial communities were generated using DGGE (denaturing gradient gel electrophoresis). Pearson correlation analysis and CCA (canonical correspondence analysis) were employed to determine effects of sediment properties on benthic microbial communities. Experimental results showed that marginal and compound pollutions, tolerable for most benthic organisms, were found in sediments of Poyang Lake according to contents of nutrients and heavy metals. However, pollutions was severe in Rao and Xin River estuaries and especially copper pollution. Also, bacterial communities in the sediments had apparently horizontal heterogeneity and genotypic richness and diversity of microbial communities were predicted by sediment nutrients. Finally, total phosphorus (TP), heavy metal copper (Cu), and cadmium (Cd) in sediment were considered to be key factors driving spatial variation of bacterial community structures in Poyang Lake. This study suggested heavy metals together with phosphates may jointly affect benthic microbial communities and metal-reduction was an important microbial activity in freshwater sediment.