DOI: 10.1002/2014GB004886
Scopus记录号: 2-s2.0-84910139119
论文题名: Heterotrophic bacteria as major nitrogen fixers in the euphotic zone of the Indian Ocean
作者: Shiozaki T ; , Ijichi M ; , Kodama T ; , Takeda S ; , Furuya K
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2014
卷: 28, 期: 10 起始页码: 1096
结束页码: 1110
语种: 英语
英文关键词: heterotrophic bacteria
; Indian Ocean
; nifH
; nitrogen fixation
Scopus关键词: bacterium
; community structure
; euphotic zone
; heterotrophy
; high temperature
; iron
; nitrogen fixation
; oligotrophic environment
; phosphate
; Arabian Sea
; Indian Ocean
英文摘要: Diazotrophy in the Indian Ocean is poorly understood compared to that in the Atlantic and Pacific Oceans. We first examined the basin-scale community structure of diazotrophs and their nitrogen fixation activity within the euphotic zone during the northeast monsoon period along about 69°E from 17°N to 20°S in the oligotrophic Indian Ocean, where a shallow nitracline (49-59 m) prevailed widely and the sea surface temperature (SST) was above 25°C. Phosphate was detectable at the surface throughout the study area. The dissolved iron concentration and the ratio of iron to nitrate + nitrite at the surface were significantly higher in the Arabian Sea than in the equatorial and southern Indian Ocean. Nitrogen fixation in the Arabian Sea (24.6-47.1 μmolN m-2 d-1) was also significantly greater than that in the equatorial and southern Indian Ocean (6.27-16.6 μmolN m-2 d-1), indicating that iron could control diazotrophy in the Indian Ocean. Phylogenetic analysis of nifH showed that most diazotrophs belonged to the Proteobacteria and that cyanobacterial diazotrophs were absent in the study area except in the Arabian Sea. Furthermore, nitrogen fixation was not associated with light intensity throughout the study area. These results are consistent with nitrogen fixation in the Indian Ocean, being largely performed by heterotrophic bacteria and not by cyanobacteria. The low cyanobacterial diazotrophy was attributed to the shallow nitracline, which is rarely observed in the Pacific and Atlantic oligotrophic oceans. Because the shallower nitracline favored enhanced upward nitrate flux, the competitive advantage of cyanobacterial diazotrophs over nondiazotrophic phytoplankton was not as significant as it is in other oligotrophic oceans. Key Points Heterotrophic bacteria dominate in diazotrophs in the Indian OceanDiazotrophy in the Indian Ocean would be controlled by iron supplyThe shallow nitracline and high temperature exclude cyanobacterial diazotrophs © 2014. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77537
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan; Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan; Japan Sea National Research Institute of Fisheries Science, Fisheries Research Agency, Niigata, Japan; Faculty of Fisheries, Nagasaki University, Nagasaki, Japan
Recommended Citation:
Shiozaki T,, Ijichi M,, Kodama T,et al. Heterotrophic bacteria as major nitrogen fixers in the euphotic zone of the Indian Ocean[J]. Global Biogeochemical Cycles,2014-01-01,28(10)