深圳近海表层浮游细菌分布特征及其环境影响因素

摘要

In marine ecosystems,the distribution pattern and abundance of bacterioplankton are directly related to environmental conditions.In order to study the effect of environmental factors on bacterial abundance,surface water samples were collected in March,May,August,and October 2015 from three coastal regions namely,the Pearl River Estuary,Shenzhen Bay and Daya Bay in Shenzhen,China.The abundance of bacterioplankton,bacteria with high DNA content (HNA subgroup bacteria) and bacteria with low DNA content (LNA subgroup bacteria) in the coastal waters of Shenzhen were measured by flow cytometry to analyze their temporal and spatial distribution pattern and to explore their responses to environmental factors.The results showed that the average abundance of bacterioplankton in Shenzhen Bay (7.67 × 106 cells/mL),the Pearl River Estuary (3.82 × 106 cells/mL),and Daya Bay (3.38 × 106 cells/mL) had a decreasing trend.The abundance of bacterioplankton in the Pearl River Estuary increased from far coast to near coast sites;however,there were no significant differences in abundance among the sites in Shenzhen Bay (P ＞ 0.05) and Daya Bay (P ＞ 0.05).The temporal variation in bacterioplankton abundance in the three regions was mainly affected by temperature,whereas spatial variation was predominantly controlled by the concentration of chlorophyll a and nutrient matter,such as nitrogen and phosphorus.Additionally,the temporal and spatial variability of HNA subgroup bacterial abundance was greater than that of LNA subgroup bacteria (P ＜ 0.01).The HNA subgroup bacteria was significantly affected by temperature (P ＜ 0.01) whereas LNA subgroup bacteria were not (P ＞ 0.05).The different responses of HNA and LNA subgroup bacteria to certain environmental factors imply that they play partially overlapping but slightly different roles in the coastal ecosystem.%于2015年3月、5月、8月和10月在深圳市近岸海域(珠江口、深圳湾和大亚湾)采集表层水样,利用流式细胞仪测定总浮游细菌、高DNA含量亚群细菌(HNA)、低DNA含量亚群细菌(LNA)的丰度,分析它们的时空分布特点,阐释环境因子对浮游细菌时空分布格局的影响.结果表明,珠江口、深圳湾和大亚湾海域表层浮游细菌的平均丰度依次降低,分别为3.82×106个/mL、7.67×106个/mL和3.38×106个/mL.珠江口海域浮游细菌丰度由远岸到近岸递增,深圳湾海域湾内各站位浮游细菌丰度差异较小,大亚湾海域浮游细菌丰度空间差异不显著(P＞0.05).浮游细菌丰度时间差异主要受温度影响,空间差异主要受营养盐和叶绿素a影响.HNA亚群丰度时空差异性比LNA亚群的大,HNA亚群受温度影响显著(P＜0.01),而LNA亚群与温度相关性不显著(P＞ 0.05).环境对HNA和LNA亚群丰度的影响有许多相似之处,但两者对某些环境因子有着不同的响应,说明它们在近海表层生态系统中可能扮演着部分重叠但略有不同的角色.