Spatial heterogeneity in a deep artificial lake plankton community revealed by PCR-DGGE fingerprinting

To explore the spatial heterogeneity of plankton communities in a deep artificial lake(Songhua Lake,China),samples were collected at seven sites. Samples were investigated by denaturing gradient gel electrophoresis(DGGE) analysis of the PCR-amplified 16 S and 18 S r RNA genes and specif ic bands were sequenced. Cluster analysis of the DGGE profiles revealed that all of the samples grouped into two distinct clusters,in accordance with sampling site; while in each cluster,the divergence of sub-clusters correlated with sampling depth. Sequence analysis of selected dominant DGGE bands revealed that most sequenced phylotypes(84%) exhibited ≥97% similarity to the closest sequences in Gen Bank,and were affiliated with ten common freshwater plankton phyla(Proteobacteria,Actinobacteria,Bacteroidetes,Cyanobacteria,Bacillariophyta,Pyrrophyta,Cryptophyta,Ciliophora,Stramenopiles,and R otifera). Several of these groups are also found worldwide,indicating the cosmopolitan distribution of the phylotypes. The relationships between DGGE patterns and environmental factors were analyzed by redundancy analysis(RDA). The results suggested that,total nitrogen,nitrate,nitrite,ammonia,and CODM n concentrations,and water temperature were strongly correlated with the variation in plankton composition.