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The influence of iron and light on net community production in the Subantarctic and Polar Frontal Zones

Citation

Cassar, N and DiFiore, PJ and Barnett, BA and Bender, ML and Bowie, AR and Tilbrook, B and Petrou, K and Westwood, KJ and Wright, SW and Lefevre, D, The influence of iron and light on net community production in the Subantarctic and Polar Frontal Zones, Biogeosciences, 8, (2) pp. 227-237. ISSN 1726-4170 (2011) [Refereed Article]


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Licensed under the Creative Commons Attibution 3.0 Unported (CC BY 3.0) http://creativecommons.org/licenses/by/3.0/legalcode

DOI: doi:10.5194/bg-8-227-2011

Abstract

The roles of iron and light in controlling biomass and primary productivity are clearly established in the Southern Ocean. However, their influence on net community production (NCP) and carbon export remains to be quantified. To improve our understanding of NCP and carbon export production in the Subantarctic Zone (SAZ) and the northern reaches of the Polar Frontal Zone (PFZ), we conducted continuous onboard determinations of NCP as part of the Sub-Antarctic Sensitivity to Environmental Change (SAZ-Sense) study, which occurred in January-February 2007. Biological O2 supersaturation was derived from measuring O2/Ar ratios by equilibrator inlet mass spectrometry. Based on these continuous measurements, NCP during the austral summer 2007 in the Australian SAZ was approximately 43 mmol O2 m-2 d-1. NCP showed significant spatial variability, with larger values near the Subtropical front, and a general southward decrease. For shallower mixed layers (<50 m), dissolved Fe concentrations and Fe sufficiency, estimated from variable fluorescence, correlated strongly with NCP. The strong correlation between NCP and dissolved Fe may be difficult to interpret because of the correlation of dissolved Fe to MLD and because the concentration of iron may not be a good indicator of its availability. At stations with deeper mixed layers, NCP was consistently low, regardless of iron sufficiency, consistent with light availability also being an important control of NCP. Our new observations provide independent evidence for the critical roles of iron and light in mediating carbon export from the Southern Ocean mixed layer.

Item Details

Item Type:Refereed Article
Keywords:iron, Subantarctic, polar fronts
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Antarctic and Sub-Antarctic Oceanography
Author:Bowie, AR (Associate Professor Andrew Bowie)
Author:Tilbrook, B (Dr Bronte Tilbrook)
Author:Westwood, KJ (Dr Karen Westwood)
Author:Wright, SW (Dr Simon Wright)
ID Code:73200
Year Published:2011
Web of Science® Times Cited:39
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2011-09-20
Last Modified:2017-10-31
Downloads:266 View Download Statistics

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