Journal of Tropical Oceanography >
Spatial and temporal variation in heterotrophic bacteria and their regulators in the Pearl River Estuary
Received date: 2017-04-11
Request revised date: 2017-05-02
Online published: 2018-02-02
Supported by
National Natural Science Foundation of China (41476137, 41506095, 41676075)
Hundred Talent Program of Chinese Academy of Sciences (Y35L041001)
Project of State Key Laboratory of Tropical Oceanography (LTOZZ1504-1)
Copyright
Estuaries are important land-sea interaction zones with unique biogeochemical processes and are important places to study the carbon cycle. Little is known on bacterial regulation in carbon cycling in the Pearl River Estuary. To examine the relative contribution of different groups of heterotrophic bacteria (particle-attached bacteria vs free-living bacteria, and high nucleic acid bacteria vs low nucleic acid bacteria), spatial and temporal variation in heterotrophic bacterial abundance was investigated during three contrasting periods (May 2015, August 2015 and January 2016) in the Pearl River Estuary. The total bacterial abundance was the highest in spring (an average of 2.94±1.30×109 cells •L-1 at the surface and 2.81±1.50×109 cells •L-1 at the bottom), moderate in summer (2.32±0.43×109 cells •L-1 at the surface and 1.85±0.50×109 cells •L-1 at the bottom), and the lowest in winter (1.06±0.33×109 cells •L-1 at the surface and 9.76±3.44×108 cells •L-1 at the bottom). Bacterial abundance at the surface was slightly higher than that at the bottom. Bacterial abundance decreased spatially from the upstream to the downstream of the estuary, suggesting that sewage input contributed to high bacterial abundance in the upstream, and that the downstream decrease resulted from the mixing of river discharge and seawater. The peaks of bacterial abundance and Chl a were observed at the frontal zone in the wet season, since a front increased the residence time of nutrients and plankton, and favored plankton growth. According to the spatial variation trend of bacterial abundance, it could be inferred that the heterotrophic bacteria of the estuary mainly came from upstream inputs. Heterotrophic bacterial communities were dominated by particle-attached bacteria, which accounted for 78.65%, 70.32% and 68.17% of the total bacterial abundance in spring, summer and winter, respectively. The metabolically active bacteria with high nucleic acid dominated in the particle-attached bacteria, while the low nucleic acid group was the dominant component of the free-living bacteria.
LI Xiangfu , XU Jie , SHI Zhen , LI Ruihuan . Spatial and temporal variation in heterotrophic bacteria and their regulators in the Pearl River Estuary[J]. Journal of Tropical Oceanography, 2018 , 37(1) : 27 -36 . DOI: 10.11978/2017042
Fig. 1 Map of sampling locations图1 采样站位图 |
Fig. 2 Spatial and temporal distributions of temperature, salinity and the concentrations of suspended particulate matter, inorganic nutrients (dissolved inorganic nitrogen, phosphate and silicate), dissolved organic carbon and Chl a in the Pearl River Estuary图2 珠江口水体温度、盐度、悬浮颗粒物质量浓度、营养盐(溶解无机氮、磷酸盐、硅酸盐)浓度、溶解有机碳浓度和叶绿素a质量浓度的时空分布 |
Fig. 3 Spatio-temporal distributions of total heterotrophic bacterial abundance (TBA), particle-attached bacterial abundance (PBA) and its proportion to the total heterotrophic bacterial abundance (PBA%) in the Pearl River Estuary. Bacterial samples were lost at the surface of Station S1 and at the bottom of Stations S1 & S7 in May 2015图3 珠江口异养细菌丰度(TBA)、附生细菌丰度(PBA)及附生细菌所占比率(PBA%)的时空分布 |
Fig. 4 Spatio-temporal distributions of two subgroups (LNA and HNA bacteria) of free-living bacteria and particle-attached bacteria in the Pearl River Estuary.图4 珠江口游离细菌和附生细菌的高、低核酸类群的时空分布 |
Tab. 1 Pearson correlation coefficients between heterotrophic bacterial abundance and environmental factors in the Pearl River Estuary表1 珠江口异养细菌丰度与环境因子相关性分析结果 |
温度 | 盐度 | SPM | NO- 3 | NO-2 | NH+ 4 | PO3- 4 | SiO2- 4 | DOC | Chl a | ||
---|---|---|---|---|---|---|---|---|---|---|---|
201505 | TBA# | -0.67* | 0.71* | 0.76** | 0.78* | 0.76* | 0.73* | 0.69* | |||
THNA% | -0.94** | 0.94** | 0.84** | 0.94** | 0.93** | 0.59* | |||||
FBA | 0.56* | ||||||||||
FHNA% | |||||||||||
PBA# | -0.70* | 0.78** | 0.71* | 0.72** | 0.64* | 0.75** | 0.66* | ||||
PHNA% | -0.82** | 0.60* | |||||||||
PBA% | -0.84** | 0.65* | 0.68* | 0.656* | 0.69** | 0.76** | |||||
201508 | TBA | 0.68** | -0.50* | 0.52* | |||||||
THNA% | 0.56* | ||||||||||
FBA | 0.54* | -0.50* | 0.51* | 0.57* | |||||||
FHNA% | |||||||||||
PBA | |||||||||||
PHNA% | 0.72** | -0.72** | 0.67* | 0.67* | |||||||
PBA% | |||||||||||
201601 | TBA | -0.63** | -0.56* | 0.54* | 0.66** | 0.54* | |||||
THNA% | -0.83** | -0.86** | 0.84** | 0.58* | 0.64* | 0.77** | 0.82** | ||||
FBA | -0.83** | -0.76** | 0.75* | 0.57* | 0.56* | 0.52* | 0.56* | ||||
FHNA% | |||||||||||
PBA | -0.53* | -0.52* | 0.51* | 0.68** | |||||||
PHNA% | -0.75** | -0.76** | 0.76** | 0.58* | 0.73** | 0.69* | |||||
PBA% | -0.68** | -0.63** | 0.59* | 0.53* |
注: THNA%: 异养细菌中HNA类细菌所占百分比; FHNA%: 游离细菌中HNA类细菌所占百分比; PHNA%: 游离细菌中HNA类细菌所占百分比; #: 除去S6站位数据后的相关性(S6站异养细菌高丰度可能主要是由物理聚集作用造成的); 空格: 无显著相关性; *: p<0.05; **: p<0.01 |
Tab. 2 Stepwise multiple linear regression analysis between heterotrophic bacterial abundance and environmental factors in the Pearl River Estuary表2 珠江口异养细菌丰度与环境因子间逐步多元线性回归分析结果 |
航次时间 | 线性回归方程 | |
---|---|---|
201505 | TBA=1.50[±0.18]×109 + 1.52[±0.29]×108 Chl a | r2=0.800, p<0.01 |
PBA=8.88[±2.14]×108 + 1.33[±0.33]×108 Chl a | r2=0.693, p<0.01 | |
201508 | PBA=1.04[±0.11]×109 + 1.02[±0.28]×108 Chl a | r2=0.821, p<0.05 |
201601 | TBA=7.46[±1.97]×107 + 9.20[±3.15]×107 Chl a + 7.25[±1.32]×107 NO- 2 | r2=0.732, p<0.01 |
FBA=3.55[±0.60]×109 - 1.79[±0.32]×108 T | r2=0.739, p<0.01 | |
PBA=3.85[±1.29]×108 - 4.49[±1.21]×107 NO- 2 | r2=0.534, p<0.01 |
注: T: 水体温度 |
The authors have declared that no competing interests exist.
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