Abstract

Temporal bacterial community dynamics in the coastal northwest Atlantic Ocean
Heba El-Swais

Marine microbial communities are essential drivers of globally important processes, including carbon, nitrogen, iron and sulfur cycles. Because these diverse bacteria play crucial roles, understanding the structure of microbial communities across space and time is important. This will allow better comprehension of the earth’s response to global change. In this study, we used 16S rRNA sequencing to investigate the temporal shifts in bacterial community structure in surface communities in a coastal inlet in the Northwest Atlantic Ocean (Bedford Basin). We demonstrated that in the spring the dominant bacterial groups were the Bacteroidetes, particularly Polaribacter and Cytophaga. The nutrient-poor summer is associated with the alpha-proteobacterial oligotrophic lineage SAR11. Alteromonadales and SAR11 characterize autumn, and winter is strongly associated with Gamma-proteobacterial sulfur oxidizers (GSO) group. We have established that bacterial richness is highest in winter, which is consistent with global latitudinal studies of bacteria. We further demonstrated that similarity between surface bacterial communities varied according to different time-scales. We showed that high-frequency sampling can reveal episodic blooms from the rare bacterial biosphere. In summary, we used a multi-scale study to reveal the temporal dynamics of bacterial community structure in the temperate North Atlantic coastal ocean.