Biological nitrogen fixation in the oxygen-minimum region of the eastern tropical North Pacific ocean

Jayakumar, Amal; Chang, Bonnie X; Widner, Brittany; Bernhardt, Peter; Mulholland, Margaret R; Ward, Bess B

doi:10.1038/ismej.2017.97

i

Biological nitrogen fixation in the oxygen-minimum region of the eastern tropical North Pacific ocean

2017
By Jayakumar, Amal ; Chang, Bonnie X ; Widner, Brittany ; ...
Series: PMEL contribution no. 4566

Details

Journal Title:

The ISME Journal
Personal Author:

Jayakumar, Amal ; Chang, Bonnie X ; Widner, Brittany ; Bernhardt, Peter ; Mulholland, Margaret R ; Ward, Bess B
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; JISAO (Joint Institute for the Study of the Atmosphere and Ocean) ; PMEL (Pacific Marine Environmental Laboratory)
Description:

Biological nitrogen fixation (BNF) was investigated above and within the oxygen-depleted waters of the oxygen-minimum zone of the Eastern Tropical North Pacific Ocean. BNF rates were estimated using an isotope tracer method that overcame the uncertainty of the conventional bubble method by directly measuring the tracer enrichment during the incubations. Highest rates of BNF (~4 nm day−1) occurred in coastal surface waters and lowest detectable rates (~0.2 nm day−1) were found in the anoxic region of offshore stations. BNF was not detectable in most samples from oxygen-depleted waters. The composition of the N2-fixing assemblage was investigated by sequencing of nifH genes. The diazotrophic assemblage in surface waters contained mainly Proteobacterial sequences (Cluster I nifH), while both Proteobacterial sequences and sequences with high identities to those of anaerobic microbes characterized as Clusters III and IV type nifH sequences were found in the anoxic waters. Our results indicate modest input of N through BNF in oxygen-depleted zones mainly due to the activity of proteobacterial diazotrophs.
Source:

The ISME Journal, 11(10), 2356-2367
Series:

PMEL contribution no. 4566
DOI:

https://doi.org/10.1038/ismej.2017.97
ISSN:

1751-7362 ; 1751-7370
Format:

pdf
Publisher:

Oxford University Press (OUP)
Document Type:

Journal Article
Funding:

Grant no. NA10OAR4320148 ; Grant no. NA15OAR4320063
Rights Information:

Accepted Manuscript
Compliance:

Submitted
Main Document Checksum:

urn:sha-512:e240d89b4a2e98de87231fe72bc9a1d1154f8b7f95698975f7b0d2a24e6107b2f3a0a02663ec36d7effa469f9944751335113e1581e5a1c72d66fcb595eafc57
Download URL:

https://repository.library.noaa.gov/view/noaa/72324/noaa_72324_DS1.pdf
File Type:

[PDF - 1.04 MB ]

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