The Spatial And Temporal Feature Of Bacterial Abundance And Community Structure In The Surface Microlayer And Subsurface Layer Of The Northern Yellow Sea

In this study, bacterial abundance and community structure were investigated using seawater samplescollected from the surface microlayer and subsurface layer of the North Yellow Sea from March2011toJanuary2012. The total numbers of bacteria, culturable bacteria, DGGE and sequencing analysis were used inthis study. The results showed that the average concentration of the total bacteria in the surface microlayer inthe investigated area was three times higher than that in the subsurface layer. The average concentration of thetotal culturable bacteria was an order of magnitude higher than that in the subsurface layer, confirming anobvious enrichment effect of the surface microlayer. The spatial and temporal anylance of the total numbers ofbacteria and culturable bacteria in surface microlayer and subsurface layer showed that bacteria had a morehigher number in spring, summer and autumn, which may be due to warmer temperature is more suitable forbacterial growth. The other side total numbers of bacteria and culturable bacteria are at the lowest of the yearin winter. The differences of the total number of bacteria and culturable bacteria in spance, the nearshorebacteria abundance higher than that in open sea in the surface microlayer, this may be due to offshore has morerich nutrition supply caused by the bacteria growth. The selected two offshore stance, which (B1) is muchhigher than (A1) of the bacteria abundance, this may be the environmental degradation caused by excessiveenrichment of inorganic, organic material, may inhibit the growth of bacteria.DGGE and sequencing revealed aclose relationship between the bacterial community in the surface microlayer and subsurface layer, with highsimilarities between the two dominant bacterial communities, Proteobacteria and Bacteroidetes. However,these organisms also varied with changes in spatial and temporal factors. Different communities of bacteriapresent different distribution characteristics with changes in seasons in the surface microlayer and subsurfacelayer. The bacterial communities in the surface microlayer and subsurface also varied with time. Furthermore,the bacterial abundance of nearshore seawater in the surface microlayer was significantly higher than in theopen sea, but this was not the case for the subsurface layer. This was likely because coastal areas are moreheavily influenced by surface runoff and human factors, resulting in the enrichment with a large number oforganic and inorganic materials in the surface microlayer and a favorable environment for microbial survival.