南海南部海域浮游细菌群落特征及影响因素研究

采用高通量测序技术,对南海南部海域浮游细菌丰度、群落组成和群落多样性的分布特征及与环境因子的关系进行了研究.结果表明,该研究区域浮游细菌丰度为107~108个/L,近岸大于离岸,同一站位不同水层细菌分布差异明显.优势类群为变形菌门、蓝藻门和拟杆菌门,优势亚群为 γ-变形菌纲、α-变形菌纲、蓝藻菌纲和黄杆菌纲,研究区域内不同水体间物种组成存在较大差异,另外该海域还存在大量未被认知的细菌类群.该海域浮游细菌种类丰富,具有较高的多样性指数(H￠)(4.44~7.00),研究区域内表层水体H￠接近,分别为5.26、5.33和5.07,处于上升流的次表层水体中H￠为6.70明显高于其他水层.DOC和磷酸盐是影响该海域浮游细菌丰度的主要因素,同时磷酸盐也是影响其群落多样性的主要因素,表明该海域异养浮游细菌生长主要受P的限制.

Community structure and influencing factors of bacterioplankton in the southern South China Sea

The high-throughput sequencing approach was adopted to analyze the distribution characteristics of the abundance, community structure and community diversity of bacterioplankton in the southern South China Sea and their relationship with environmental factors. The results indicated that the bacterioplankton abundance in the investigated area was about 107~108cells/L with high values in offshore stations and sharp differences among water layers. The dominant groups were Proteobacteria, Cyanobacteria and Bacteroidetes and the dominant classes were γ-Proteobacteria, α-Proteobacteria, Cyanobacterium and Flavobacteria. The community structure of bacterioplankton showed an obvious difference among various water bodies and numerous unidentified bacteria were recorded. The bacterioplankton showed a high species richness in the area with a biodiversity index (H') of between 4.44~7.00. The biodiversity index in surface layers of the area was 5.26, 5.33 and 5.07, respectively, whereas the index in the upwelling subsurface layer was 6.70, which was significantly higher than other layers. DOC and phosphate were the main factors influencing the bacterioplankton abundance, phosphate was also the main factor affecting the community diversity. The growth of bacterioplankton in the southern South China Sea was therefore mainly limited by phosphate.