海底地下水排放对南黄海沿岸海水细菌群落结构的影响

在南黄海沿岸岸滩采集海水样品,将同位素地球化学与分子生物学技术相结合,探讨海底地下水排放(submarine groundwater discharge, SGD)对沿岸海水微生物群落结构的影响.结果表明,南黄海沿岸水体微生物优势类群为变形菌门、放线菌门、拟杆菌门、蓝细菌门、疣微菌门、厚壁菌门等.海水中较高浓度的镭同位素活度极有可能是由近岸海底地下水排放过程导致.沿岸海水中的²²⁴Ra活度与营养盐浓度、微生物群落的多样性及丰富度具有相对同步的变化规律.溶解氧对海水中的细菌群落结构具有显著影响(p<0.05),海底地下水排放输入的高浓度溶解无机氮、溶解硅酸盐可能是影响沿岸海水中细菌群落结构特征的主要因素之一.本研究表明,海底地下水排放对沿岸微生物群落结构的影响是不可忽视的.

Effects of submarine groundwater discharge on bacterial community structure in the coastal waters of South Yellow Sea

In this study, the groundwater and seawater samples were collected along the coastal shorelines of the South Yellow Sea. The isotopic geochemistry and molecular biology techniques were combined to explore the impact of submarine groundwater discharge (SGD) on the microbial community structure in coastal seawater. The results showed that the dominant microbial groups were Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Verrucomicrobia and Firmicutes. The higher concentration of radium isotope in seawater is most likely caused by the near-shore submarine groundwater discharge process. The activity levels of ²²⁴Ra in coastal seawater had relatively synchronized changes with nutrient concentration, microbial community diversity and abundance. Dissolved oxygen had significant influence to the bacterial community structure (p<0.05). The high concentrations of dissolved inorganic nitrogen and dissolved silicate input by submarine groundwater discharge would be main reasons to affect the characteristics of bacterial community structure in coastal seawater. By predicting the metabolic function of bacterial community, it was found that the levels of amino acid metabolism, carbohydrate metabolism, lipid metabolism, xenobiotics biodegradation and metabolism of microorganisms in the high-concentration nutrient stations were higher than which in the low-concentration nutrient ones. This study indicates that it cannot be neglected that the influence of submarine groundwater discharge on coastal microorganism community.