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Ambient nitrate switches the ammonium consumption pathway in the euphotic ocean


Wan, XS and Sheng, HX and Dai, M and Zhang, Y and Shi, D and Trull, T and Zhu, Y and Lomas, MW and Kao, SJ, Ambient nitrate switches the ammonium consumption pathway in the euphotic ocean, Nature Communications, 9, (1) Article 915. ISSN 2041-1723 (2018) [Refereed Article]


Copyright Statement

Copyright 2018 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.1038/s41467-018-03363-0


Phytoplankton assimilation and microbial oxidation of ammonium are two critical conversion pathways in the marine nitrogen cycle. The underlying regulatory mechanisms of these two competing processes remain unclear. Here we show that ambient nitrate acts as a key variable to bifurcate ammonium flow through assimilation or oxidation, and the depth of the nitracline represents a robust spatial boundary between ammonium assimilators and oxidizers in the stratified ocean. Profiles of ammonium utilization show that phytoplankton assemblages in nitrate-depleted regimes have higher ammonium affinity than nitrifiers. In nitrate replete conditions, by contrast, phytoplankton reduce their ammonium reliance and thus enhance the success of nitrifiers. This finding helps to explain existing discrepancies in the understanding of light inhibition of surface nitrification in the global ocean, and provides further insights into the spatial linkages between oceanic nitrification and new production.

Item Details

Item Type:Refereed Article
Keywords:nitrate, ammonium consumption, phytoplankton, marine nitrogen cycle
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Measurement and assessment of marine water quality and condition
UTAS Author:Trull, T (Professor Thomas Trull)
ID Code:131898
Year Published:2018
Web of Science® Times Cited:34
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2019-04-11
Last Modified:2019-05-31
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