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A “shallow bathtub ring” of local sedimentary iron input maintains the Palmer Deep biological hotspot on the West Antarctic Peninsula shelf

A “shallow bathtub ring” of local sedimentary iron input maintains the Palmer Deep biological hotspot on the West Antarctic Peninsula shelf
A “shallow bathtub ring” of local sedimentary iron input maintains the Palmer Deep biological hotspot on the West Antarctic Peninsula shelf
Palmer Deep (PD) is one of several regional hotspots of biological productivity along the inner shelf of the West Antarctic Peninsula. The proximity of hotspots to shelf-crossing deep troughs has led to the ‘canyon hypothesis’, which proposes that circumpolar deep water flowing shoreward along the canyons is upwelled on the inner shelf, carrying nutrients including iron (Fe) to surface waters, maintaining phytoplankton blooms. We present here full-depth profiles of dissolved and particulate Fe and manganese (Mn) from eight stations around PD, sampled in January and early February of 2015 and 2016, allowing the first detailed evaluation of Fe sources to the area’s euphotic zone. We show that upwelling of deep water does not control Fe flux to the surface; instead, shallow sediment- sourced Fe inputs are transported horizontally from surrounding coastlines, creating strong vertical gradients of dissolved Fe within the upper 100m that supply this limiting nutrient to the local ecosystem. The supply of bioavailable Fe is, therefore, not significantly related to the canyon transport of deep water. Near shore time-series samples reveal that local glacial meltwater appears to be an importantMn source but, surprisingly, is not a large direct Fe input to this biological hotspot. This article is part of the theme theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.
1364-503X
Sherrell, Robert M.
251b287a-1ac0-48aa-a422-edeed2427c22
Annett, Amber
de404d72-7e90-4dbd-884a-1df813808276
Fitzsimmons, Jessica N.
0f0dda9d-71c8-4e05-91fe-0e5c5996a74a
Roccanova, Vincent
5bbdd72e-0b61-4438-b2bd-4cbfafe8c26f
Meredith, Michael P.
25fd5f1c-f3ed-40a2-af59-5a7074a25fcd
Sherrell, Robert M.
251b287a-1ac0-48aa-a422-edeed2427c22
Annett, Amber
de404d72-7e90-4dbd-884a-1df813808276
Fitzsimmons, Jessica N.
0f0dda9d-71c8-4e05-91fe-0e5c5996a74a
Roccanova, Vincent
5bbdd72e-0b61-4438-b2bd-4cbfafe8c26f
Meredith, Michael P.
25fd5f1c-f3ed-40a2-af59-5a7074a25fcd

Sherrell, Robert M., Annett, Amber, Fitzsimmons, Jessica N., Roccanova, Vincent and Meredith, Michael P. (2018) A “shallow bathtub ring” of local sedimentary iron input maintains the Palmer Deep biological hotspot on the West Antarctic Peninsula shelf. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 376 (2122), [20170171]. (doi:10.1098/rsta.2017.0171).

Record type: Article

Abstract

Palmer Deep (PD) is one of several regional hotspots of biological productivity along the inner shelf of the West Antarctic Peninsula. The proximity of hotspots to shelf-crossing deep troughs has led to the ‘canyon hypothesis’, which proposes that circumpolar deep water flowing shoreward along the canyons is upwelled on the inner shelf, carrying nutrients including iron (Fe) to surface waters, maintaining phytoplankton blooms. We present here full-depth profiles of dissolved and particulate Fe and manganese (Mn) from eight stations around PD, sampled in January and early February of 2015 and 2016, allowing the first detailed evaluation of Fe sources to the area’s euphotic zone. We show that upwelling of deep water does not control Fe flux to the surface; instead, shallow sediment- sourced Fe inputs are transported horizontally from surrounding coastlines, creating strong vertical gradients of dissolved Fe within the upper 100m that supply this limiting nutrient to the local ecosystem. The supply of bioavailable Fe is, therefore, not significantly related to the canyon transport of deep water. Near shore time-series samples reveal that local glacial meltwater appears to be an importantMn source but, surprisingly, is not a large direct Fe input to this biological hotspot. This article is part of the theme theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

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Accepted/In Press date: 1 February 2018
e-pub ahead of print date: 14 May 2018
Published date: June 2018

Identifiers

Local EPrints ID: 422588
URI: http://eprints.soton.ac.uk/id/eprint/422588
ISSN: 1364-503X
PURE UUID: 8e61f2a6-7865-4443-a129-d1d5e1424b62
ORCID for Amber Annett: ORCID iD orcid.org/0000-0002-3730-2438

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Date deposited: 25 Jul 2018 16:30
Last modified: 16 Mar 2024 06:38

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Contributors

Author: Robert M. Sherrell
Author: Amber Annett ORCID iD
Author: Jessica N. Fitzsimmons
Author: Vincent Roccanova
Author: Michael P. Meredith

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