Synechococcus is an important primary producer in the global ocean. Synechococcus displayed spatial variation due to various environmental factors. Salinity are one of the factors that cause Synechococcus partitioning, which in turn changed the interaction between Synechococcus and heterotrophic bacteria. In this study, we revealed that salinity determines the abundance and diversity of the community. Synechococcus and heterotrophic bacteria abundance increased positively according to salinity. Synechococcus community shifted from S5.1 dominated to S5.2 dominated when salinity is lowered, due to the fact that S5.1 cannot survive at low salinity (<15 ppt). Moreover, diversity of Synechococcus is predicted to be highest at mid salinity at around 20-25 ppt. The development of PE pigment of some S5.2 Synechococcus expands the niche of S5.2 greatly. Heterotrophic bacterial community also responded to the change of salinity. Alteromonadaceae and Saprospiraceae, which utilize phytoplankton-derived carbon, dominated at high salinity, suggesting that they may be highly dependent on Synechococcus produced substrate. While the bacterial community shifted when salinity increased, functions performed by the community showed no significant change. Nevertheless, to deal with lowered salinity environment, bacterial community spent more energy for DNA repair, while less RNA transport implied lower activity of the community.

...[ Read more ]

Synechococcus is an important primary producer in the global ocean. Synechococcus displayed spatial variation due to various environmental factors. Salinity are one of the factors that cause Synechococcus partitioning, which in turn changed the interaction between Synechococcus and heterotrophic bacteria. In this study, we revealed that salinity determines the abundance and diversity of the community. Synechococcus and heterotrophic bacteria abundance increased positively according to salinity. Synechococcus community shifted from S5.1 dominated to S5.2 dominated when salinity is lowered, due to the fact that S5.1 cannot survive at low salinity (<15 ppt). Moreover, diversity of Synechococcus is predicted to be highest at mid salinity at around 20-25 ppt. The development of PE pigment of some S5.2 Synechococcus expands the niche of S5.2 greatly. Heterotrophic bacterial community also responded to the change of salinity. Alteromonadaceae and Saprospiraceae, which utilize phytoplankton-derived carbon, dominated at high salinity, suggesting that they may be highly dependent on Synechococcus produced substrate. While the bacterial community shifted when salinity increased, functions performed by the community showed no significant change. Nevertheless, to deal with lowered salinity environment, bacterial community spent more energy for DNA repair, while less RNA transport implied lower activity of the community.