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131898 - Ambient nitrate switches the ammonium consumption pathway.pdf (1.2 MB)

Ambient nitrate switches the ammonium consumption pathway in the euphotic ocean

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posted on 2023-05-20, 02:43 authored by Wan, XS, Sheng, HX, Dai, M, Zhang, Y, Shi, D, Trull, T, Zhu, Y, Lomas, MW, Kao, SJ
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.

History

Publication title

Nature Communications

Volume

9

Article number

915

Number

915

Pagination

1-9

ISSN

2041-1723

Department/School

Institute for Marine and Antarctic Studies

Publisher

Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2018 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

Repository Status

  • Open

Socio-economic Objectives

Measurement and assessment of marine water quality and condition

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