Using detaching method to determine the abundance of particle-attached bacteria from the Pearl River Estuary and its coupling relationship with environmental factors

Export fluxes of sinking particulate organic carbon (POC) are important for the function of biological carbon pump. Vertical transportation of POC into the ocean interior can be affected by particle-attached bacteria (PAB) via the change of their abundance and activities, which may eventually affect the carbon sequestration into the ocean. In order to better understand the characteristics of PAB in the turbid nearshore waters along the Pearl River Estuary (PRE), we applied and modified an existing analytical procedure to effectively detach PAB from sinking particles for more direct and accurate estimation of PAB. The coupling relationship between environmental factors and the abundance of PAB were further analyzed and discussed. our results suggested that PAB from the fraction 2~20 μm particles was the dominant component of PAB in all stations. Moreover, there was a spatial change of PAB along the PRE with the highest abundance at Xiangzhou port (4.21×10⁹ cells/L), following by Zhongda port (1.13×10⁹ cells/L) and Wanshan island (0.27×10⁹ cells/L). We also found that suspended organic particles might have supported PAB growth at Xiangzhou port where there was high PAB but low chlorophyll a. In addition, the growth of PAB might also subject to influences by varying concentrations and species compositions of inorganic nutrients in coastal waters. These results may be important for further understanding of PAB associated biogeochemical processes in coastal ecosystem.