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Phytoplankton bloom has imposed ecological concerns worldwide; however, few studies have been focused on the successional trajectories of bacterioplankton community over a complete phytoplankton bloom cycle. Using 16S pyrosequencing, we investigated how the coastal bacterioplankton community compositions (BCCs) respond to a phytoplankton bloom in the Xiangshan Bay, East China Sea. The results showed that BCCs were significantly different among the pre-bloom, bloom, and after-bloom stages, with the lowest bacterial diversity at the bloom phase. The BCCs at the short-term after-bloom phase showed a rapid but incomplete recovery to the pre-bloom phase, evidenced by 69.8% similarity between pre-bloom and after-bloom communities. This recovery was parallel with the dynamics of the operational taxonomic units (OTUs) affiliated with Actinobacteria , Bacteroidetes , Cyanobacteria , Alphaproteobacteria and Gammaproteobacteria , whose abundance enriched when bloom occur, and decreased after-bloom, and vice versa . Collectively, the results showed that the BCCs were sensitive to algal-induced disturbances, but could recover to a certain extent after bloom. In addition, OTUs which enriched or decreased during this process are closely associated with this temporal pattern, thus holding the potential to evaluate and indicate the succession stage of phytoplankton bloom. [ABSTRACT FROM AUTHOR]

The underlying mechanisms of microbial community assembly in connective coastal environments are unclear. The coastal water area of northern Zhejiang, East China Sea, is a complex marine ecosystem with multiple environmental gradients, where the distributions and determinants of bacterioplankton communities remain unclear. We collected surface water samples from 95 sites across eight zones in this area for investigating bacterial community with 16S r RNA gene high-throughput sequencing. Bacterial alpha-diversity exhibits strong associations with water chemical parameters and latitude, with 75.5% of variation explained by suspended particle. The composition of dominant phyla can group the sampling sites into four bacterial provinces, and most key discriminant phyla and families/genera of each province strongly associate with specific environmental features, suggesting that local environmental conditions shape the biogeographic provincialism of bacterial taxa. At a broader and finer phylogenetic scale, bacterial beta-diversity is dominantly explained by the shared variation of environmental and spatial factors (63.3%); meanwhile, the environmental determinants of bacterial β-diversity generally exhibit spatially structured patterns, suggesting that bacterial assembly in surface water is highly controlled by spatially structured environmental gradients in this area. This study provides evidence for the unique biogeographic pattern of bacterioplankton communities at an entire scale of this marine ecosystem. [ABSTRACT FROM AUTHOR]

Anthropogenic nitrogen (N) discharges has caused eutrophication in coastal zones. Ammonia-oxidizing bacteria (AOB) convert ammonia to nitrite and play important roles in N transformation. Here, we used pyrosequencing based on the amoA gene to investigate the response of the sediment AOB community to an N pollution gradient in the East China Sea. The results showed that AOB assemblages were primarily affiliated with Nitrosospira -like lineages, and only 0.4% of those belonged to Nitrosomonas -like lineage. The Nitrosospira -like lineage was separated into four clusters that were most similar to the sediment AOB communities detected in adjacent marine regions. Additionally, one clade was out grouped from the AOB lineages, which shared the high similarities with pmoA gene. The AOB community structures substantially changed along the pollution gradient, which were primarily shaped by NH 4 + –N, NO 3 − –N, SO 4 2 − –S, TP and Eh . These results demonstrated that coastal pollution could dramatically influence AOB communities, which, in turn, may change ecosystem function. [ABSTRACT FROM AUTHOR]