DIVERSITY AND SUCCESSIONAL DYNAMICS OF PICO-CYANOBACTERIAL COMMUNITY IN LAKE ERHAI (CHINA)AS INFERRED FROM 16S rRNA GENE SEQUENCES

摘要

The biomass of autotrophic picoplankton (APP) and the biodiversity of planktonic cyanobacteria in Lake Erhai (China) were investigated. Results showed that chlorophyll a concentration in phytoplankton size <2.7 μm ranged from 0.1 μg 1~(-1) (February 2008) to 1.2 μg 1~(-1) (September 2007) in the surface water during July 2007-August 2008. The contribution of APP to the total chlorophyll a concentration in phytoplankton varied from 1.6 to 5.1%. The pat-tern of seasonal changes in the concentration of APP was similar to that of total nitrogen and total phosphorus. Phy-logenetic analyses as inferred from the partial 16S rRNA gene sequences showed great diversity of the picocyano-bacterial community in Lake Erhai, which comprised both previously identified (less abundant) and unique clusters (more abundant). Group B and Lake Erhai cluster 4 (LE-4) were ubiquitous in Lake Erhai picocyanobacterial community. Different numbers and types of clusters constituted the picocyanobacterial community with seasonal variations. A novei cluster LE-10 composed exclusively of sequences ob-tained in this study was found in July 2008.