Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean
Although the supply of iron generally limits phytoplankton productivity in the Southern Ocean, substantial seasonal blooms are observed over and downstream of the Kerguelen plateau in the Indian sector of the Southern Ocean. Surprisingly, of the oceanic blooms, those associated with the deeper south...
Published in: | Journal of Geophysical Research: Oceans |
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Online Access: | https://doi.org/10.1029/2018JC013932 http://ecite.utas.edu.au/128431 |
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ftunivtasecite:oai:ecite.utas.edu.au:128431 2023-05-15T13:55:18+02:00 Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean Schallenberg, C Bestley, S Klocker, A Trull, TW Davies, DM Gault-Ringold, M Eriksen, R Roden, NP Sander, SG Sumner, M Townsend, AT van der Merwe, P Westwood, K Wuttig, K Bowie, A 2018 https://doi.org/10.1029/2018JC013932 http://ecite.utas.edu.au/128431 en eng Wiley-Blackwell Publishing, Inc. http://dx.doi.org/10.1029/2018JC013932 Schallenberg, C and Bestley, S and Klocker, A and Trull, TW and Davies, DM and Gault-Ringold, M and Eriksen, R and Roden, NP and Sander, SG and Sumner, M and Townsend, AT and van der Merwe, P and Westwood, K and Wuttig, K and Bowie, A, Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean, Journal of Geophysical Research: Oceans, 123, (8) pp. 5986-6003. ISSN 2169-9275 (2018) [Refereed Article] http://ecite.utas.edu.au/128431 Earth Sciences Oceanography Physical Oceanography Refereed Article PeerReviewed 2018 ftunivtasecite https://doi.org/10.1029/2018JC013932 2019-12-13T22:26:40Z Although the supply of iron generally limits phytoplankton productivity in the Southern Ocean, substantial seasonal blooms are observed over and downstream of the Kerguelen plateau in the Indian sector of the Southern Ocean. Surprisingly, of the oceanic blooms, those associated with the deeper southern plateau last much longer (∼3 months) than the northern bloom (∼1‐month downstream of northern plateau). In this study, iron supply mechanisms around the southern plateau were investigated, obtaining profiles of dissolved iron (<0.2μm,dFe) to 2,000‐m deep at 25 stations during austral summer 2016. The dFe concentrations in surface waters (≤100‐m depth) ranged from below the detection limit (DL, median of 0.026nmol/kg) to 0.34nmol/kg near the Antarctic shelf, with almost half the data points below detection. These low andwith few exceptionslargely spatially invariant concentrations, presumably driven by seasonal drawdown of this essential micronutrient by phytoplankton, could not explain observed patterns in chlorophyll a. In contrast, dFe concentrations (0.051.27nmol/kg) in subsurface waters (100800m) showed strong spatial variations that can explain bloom patterns around the southern Kerguelen plateau when considered in the context of frontal locations and associated frontal processes, including upwelling, that may increase the upward supply of dFe in the region. This sustained vertical dFe supply distinguishes the southern blooms from the bloom downstream of the northern Kerguelen plateau and explains their persistence through the season. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean eCite UTAS (University of Tasmania) Antarctic Southern Ocean The Antarctic Austral Kerguelen Indian Journal of Geophysical Research: Oceans 123 8 5986 6003 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Physical Oceanography |
spellingShingle |
Earth Sciences Oceanography Physical Oceanography Schallenberg, C Bestley, S Klocker, A Trull, TW Davies, DM Gault-Ringold, M Eriksen, R Roden, NP Sander, SG Sumner, M Townsend, AT van der Merwe, P Westwood, K Wuttig, K Bowie, A Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
topic_facet |
Earth Sciences Oceanography Physical Oceanography |
description |
Although the supply of iron generally limits phytoplankton productivity in the Southern Ocean, substantial seasonal blooms are observed over and downstream of the Kerguelen plateau in the Indian sector of the Southern Ocean. Surprisingly, of the oceanic blooms, those associated with the deeper southern plateau last much longer (∼3 months) than the northern bloom (∼1‐month downstream of northern plateau). In this study, iron supply mechanisms around the southern plateau were investigated, obtaining profiles of dissolved iron (<0.2μm,dFe) to 2,000‐m deep at 25 stations during austral summer 2016. The dFe concentrations in surface waters (≤100‐m depth) ranged from below the detection limit (DL, median of 0.026nmol/kg) to 0.34nmol/kg near the Antarctic shelf, with almost half the data points below detection. These low andwith few exceptionslargely spatially invariant concentrations, presumably driven by seasonal drawdown of this essential micronutrient by phytoplankton, could not explain observed patterns in chlorophyll a. In contrast, dFe concentrations (0.051.27nmol/kg) in subsurface waters (100800m) showed strong spatial variations that can explain bloom patterns around the southern Kerguelen plateau when considered in the context of frontal locations and associated frontal processes, including upwelling, that may increase the upward supply of dFe in the region. This sustained vertical dFe supply distinguishes the southern blooms from the bloom downstream of the northern Kerguelen plateau and explains their persistence through the season. |
format |
Article in Journal/Newspaper |
author |
Schallenberg, C Bestley, S Klocker, A Trull, TW Davies, DM Gault-Ringold, M Eriksen, R Roden, NP Sander, SG Sumner, M Townsend, AT van der Merwe, P Westwood, K Wuttig, K Bowie, A |
author_facet |
Schallenberg, C Bestley, S Klocker, A Trull, TW Davies, DM Gault-Ringold, M Eriksen, R Roden, NP Sander, SG Sumner, M Townsend, AT van der Merwe, P Westwood, K Wuttig, K Bowie, A |
author_sort |
Schallenberg, C |
title |
Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
title_short |
Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
title_full |
Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
title_fullStr |
Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
title_full_unstemmed |
Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean |
title_sort |
sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the southern kerguelen plateau, southern ocean |
publisher |
Wiley-Blackwell Publishing, Inc. |
publishDate |
2018 |
url |
https://doi.org/10.1029/2018JC013932 http://ecite.utas.edu.au/128431 |
geographic |
Antarctic Southern Ocean The Antarctic Austral Kerguelen Indian |
geographic_facet |
Antarctic Southern Ocean The Antarctic Austral Kerguelen Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
http://dx.doi.org/10.1029/2018JC013932 Schallenberg, C and Bestley, S and Klocker, A and Trull, TW and Davies, DM and Gault-Ringold, M and Eriksen, R and Roden, NP and Sander, SG and Sumner, M and Townsend, AT and van der Merwe, P and Westwood, K and Wuttig, K and Bowie, A, Sustained upwelling of subsurface iron supplies seasonally persistent phytoplankton blooms around the Southern Kerguelen Plateau, Southern Ocean, Journal of Geophysical Research: Oceans, 123, (8) pp. 5986-6003. ISSN 2169-9275 (2018) [Refereed Article] http://ecite.utas.edu.au/128431 |
op_doi |
https://doi.org/10.1029/2018JC013932 |
container_title |
Journal of Geophysical Research: Oceans |
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123 |
container_issue |
8 |
container_start_page |
5986 |
op_container_end_page |
6003 |
_version_ |
1766261681854349312 |