Investigation on spatio-temporal pattern of cyanobacterial community structure by T-RFLP during overwinter and recruitment period in Taihu Lake
越冬和复苏时期太湖水体蓝藻群落结构的时空变化

In order to explore spatio-temporal pattern of cyanobacterial community structure in the period from pre-overwinter to recruitment in Taihu Lake, water samples of three vertical layers were collected at eight sites (Meiliang Bay, Zhushan Bay, Gonghu Bay, Dapu, Western part of Taihu Lake, Southern part of Taihu Lake, Lake center, and cross area) from autumn 2008 to spring 2009. The total number of T-RFs derived from all those water samples was 87, indicating high genetic diversity of cyanobacteria in Taihu Lake. Based on the relative abundances of T-RFs and cluster analysis, the similarities of different vertical samples were higher than 50%. By comparison, it was found that Microcystis spp. dominated in all sampling sites (relative abundance ranged from 17.7% to 47.5%). The number of T-RFs and cyanobacterial diversity was highest at Zhushan Bay but lowest in the western part of Taihu Lake. However, differences were not apparent among other sites (P > 0.05). Pearson correlation analysis revealed a significant negative correlation (R= -0.958) between relative abundance of Microcystis and Shannon-Weiner index. The result of ANOSIM (Analysis of similarity) indicated that the seasonal variation of cyanobacterial community and diversity were extremely significant (P < 0.01). As to the Shannon-Weiner diversity index, samples derived from recruitment period reached the highest value, while samples at pre-overwintering stage in autumn showed the lowest. Cluster analysis revealed that the samples could be divided into two representative groups: Group I consists of samples collected in autumn, while group II contains the samples collected in spring and winter which were intermingled.