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Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium

Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium
Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium
A combination of stable isotopes ((15)N) and molecular ecological approaches was used to investigate the vertical distribution and mechanisms of biological N(2) production along a transect from the Omani coast to the central-northeastern (NE) Arabian Sea. The Arabian Sea harbors the thickest oxygen minimum zone (OMZ) in the world's oceans, and is considered to be a major site of oceanic nitrogen (N) loss. Short (<48?h) anoxic incubations with (15)N-labeled substrates and functional gene expression analyses showed that the anammox process was highly active, whereas denitrification was hardly detectable in the OMZ over the Omani shelf at least at the time of our sampling. Anammox was coupled with dissimilatory nitrite reduction to ammonium (DNRA), resulting in the production of double-(15)N-labeled N(2) from (15)NO(2)(-), a signal often taken as the lone evidence for denitrification in the past. Although the central-NE Arabian Sea has conventionally been regarded as the primary N-loss region, low potential N-loss rates at sporadic depths were detected at best. N-loss activities in this region likely experience high spatiotemporal variabilities as linked to the availability of organic matter. Our finding of greater N-loss associated with the more productive Omani upwelling region is consistent with results from other major OMZs. The close reliance of anammox on DNRA also highlights the need to take into account the effects of coupling N-transformations on oceanic N-loss and subsequent N-balance estimates.
anammox, central–northeastern arabian sea, denitrification, functional gene expression, marine nitrogen loss, oxygen minimum zone
1751-7362
1660-1670
Jensen, Marlene M.
23ff1ce5-4644-4816-be78-4762c15266e0
Lam, Phyllis
996aef80-a15d-4827-aed8-1b97b378f6ad
Revsbech, Niels Peter
38ea27cf-f8cf-4943-bf6c-7698528da7de
Nagel, Birgit
6d9be1ae-a8ed-4c4f-b812-2b1eb09ebf6f
Gaye, Birgit
a7926a4d-fefe-4c09-acdf-c052addd35ae
Jetten, Mike S.M.
4fffe0a6-b5db-495b-8bae-7d72c64237e0
Kuypers, Marcel M.M.
b6288cfb-42bc-469c-93fe-8fbb40d97bec
Jensen, Marlene M.
23ff1ce5-4644-4816-be78-4762c15266e0
Lam, Phyllis
996aef80-a15d-4827-aed8-1b97b378f6ad
Revsbech, Niels Peter
38ea27cf-f8cf-4943-bf6c-7698528da7de
Nagel, Birgit
6d9be1ae-a8ed-4c4f-b812-2b1eb09ebf6f
Gaye, Birgit
a7926a4d-fefe-4c09-acdf-c052addd35ae
Jetten, Mike S.M.
4fffe0a6-b5db-495b-8bae-7d72c64237e0
Kuypers, Marcel M.M.
b6288cfb-42bc-469c-93fe-8fbb40d97bec

Jensen, Marlene M., Lam, Phyllis, Revsbech, Niels Peter, Nagel, Birgit, Gaye, Birgit, Jetten, Mike S.M. and Kuypers, Marcel M.M. (2011) Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium. The ISME Journal, 5 (10), 1660-1670. (doi:10.1038/ismej.2011.44). (PMID:21509044)

Record type: Article

Abstract

A combination of stable isotopes ((15)N) and molecular ecological approaches was used to investigate the vertical distribution and mechanisms of biological N(2) production along a transect from the Omani coast to the central-northeastern (NE) Arabian Sea. The Arabian Sea harbors the thickest oxygen minimum zone (OMZ) in the world's oceans, and is considered to be a major site of oceanic nitrogen (N) loss. Short (<48?h) anoxic incubations with (15)N-labeled substrates and functional gene expression analyses showed that the anammox process was highly active, whereas denitrification was hardly detectable in the OMZ over the Omani shelf at least at the time of our sampling. Anammox was coupled with dissimilatory nitrite reduction to ammonium (DNRA), resulting in the production of double-(15)N-labeled N(2) from (15)NO(2)(-), a signal often taken as the lone evidence for denitrification in the past. Although the central-NE Arabian Sea has conventionally been regarded as the primary N-loss region, low potential N-loss rates at sporadic depths were detected at best. N-loss activities in this region likely experience high spatiotemporal variabilities as linked to the availability of organic matter. Our finding of greater N-loss associated with the more productive Omani upwelling region is consistent with results from other major OMZs. The close reliance of anammox on DNRA also highlights the need to take into account the effects of coupling N-transformations on oceanic N-loss and subsequent N-balance estimates.

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More information

e-pub ahead of print date: 21 April 2011
Published date: 2011
Keywords: anammox, central–northeastern arabian sea, denitrification, functional gene expression, marine nitrogen loss, oxygen minimum zone
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 349913
URI: https://eprints.soton.ac.uk/id/eprint/349913
ISSN: 1751-7362
PURE UUID: fc5fe9f9-e227-41b5-825d-c61098250e70
ORCID for Phyllis Lam: ORCID iD orcid.org/0000-0003-2067-171X

Catalogue record

Date deposited: 13 Mar 2013 13:38
Last modified: 03 Dec 2019 01:36

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