| Title: | Physical Forcing Controls the Basin-Scale Occurrence of Nitrogen-Fixing Organisms in the North Pacific Ocean |
| Authors: | Cheung, Shunyan Browse this author |
| Nitanai, Risa Browse this author |
| Tsurumoto, Chihiro Browse this author |
| Endo, Hisashi Browse this author |
| Nakaoka, Shin-ichiro Browse this author →KAKEN DB |
| Cheah, Wee Browse this author |
| Lorda, Jaime Farber Browse this author |
| Xia, Xiaomin Browse this author |
| Liu, Hongbin Browse this author |
| Suzuki, Koji Browse this author →KAKEN DB |
| Keywords: | diazotrophs |
| El Niño |
| mesoscale eddies |
| nitrogen fixation |
| North Pacific |
| wind‐driven coastal upwelling |
| Issue Date: | Sep-2020 |
| Publisher: | American Geophysical Union |
| Journal Title: | Global Biogeochemical Cycles |
| Volume: | 34 |
| Issue: | 9 |
| Start Page: | e2019GB006452 |
| Publisher DOI: | 10.1029/2019GB006452 |
| Abstract: | Biological nitrogen fixation is increasingly recognized as an important source of new nitrogen in a warming ocean. However, the basin-scale spatiotemporal distribution of nitrogen-fixing organisms (diazotrophs) in the ocean and its controlling environmental factors remain unclear. Here we examined the basin-scale seasonal distribution patterns of major diazotrophs (filamentous cyanobacterialTrichodesmium, unicellular cyanobacterial UCYN-A1, and proteobacterial Gamma-A) in surface waters of the North Pacific from 2014 to 2016 with unprecedented coverage and resolution. In general, UCYN-A1,Trichodesmium, and Gamma-A were abundant during spring-autumn, summer-autumn, and spring respectively. Regarding latitudinal patterns of abundance, UCYN-A1 showed dome shape;Trichodesmiumwas gradually decreasing from low- to high-latitude regions; and Gamma-A did not show a clear pattern, which were coincident with the distinct correlations between the diazotrophs and temperature. All three diazotrophs were abundant (reached 10(6)-10(7)nifHgene copy number L-1) in the North Pacific transition zone and subtropical gyre, where the cyanobacterial diazotrophs were more abundant in both the western and eastern North Pacific than in the central North Pacific. The diazotroph abundance in the western North Pacific was positively correlated with eddy kinetic energy and sea surface height anomaly, which implies an enhancement of diazotrophs in mesoscale eddies associated with the western boundary current Kuroshio and its extension. The cyanobacterial diazotrophs were positively correlated with wind stress curl, a measurable parameter of wind-driven upwelling, in the eastern North Pacific. Our study refines the biogeography of three major diazotrophs and highlights the importance of physical forcing in mediating their dynamics. |
| Rights: | Copyright 2020 American Geophysical Union. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/80513 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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