Phenotype changes of cyanobacterial and microbial distribution characteristics of surface sediments in different periods of cyanobacterial blooms in Taihu Lake

This study investigates the morphological changes in cyanobacterial and microbial distribution characteristics of surface sediments, throughout different cyanobacterial blooms periods in Zhushan Bay, Taihu Lake. Comparative microscopic analysis of cyanobacterial morphology (n = 36) was performed during the formation period (W-1), stationary period (W-2), decline period (W-3) and decomposition period (W-4). Simultaneously, sequence analysis was performed on microbial 16S rRNA genes in sediments (n = 36) by high-throughput sequencing. The coverage of the sequencing library was very high (100%) indicating that the sequencing results well represented the microbes present in samples, among which the species richness in W-4 was the highest, while the species distribution uniformity was low. The microbial abundance distribution in all four periods showed that Firmicutes (33.45%), Cyanobacteria (30.44%), Proteobacteria (27.17%) and Bacteroidetes (7.2%) were the dominant flora, with W-1 dominated by Cyanobacteria, W-2 dominated by Firmicutes, W-3 dominated by Proteobacteria and Cyanobacteria, and W-4 dominated by Proteobacteria. There were significant differences in microbial species abundance and distribution observed during each cyanobacterial bloom period and synchronous microorganisms in the sediment regulated bacterial abundance and distribution through signal transduction of various proteases. The findings of this study help to establish the impact of cyanobacteria blooms on the sediment environment and benefit the comprehensive assessment of hazard presented by cyanobacteria to the aquatic environment.