Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf
The Weddell Sea represents a point of origin in the Southern Ocean where globally important water masses form. Biological activities in Weddell Sea surface waters thus affect large-scale ocean biogeochemistry. During January–February 2019, we measured net primary production (NPP), nitrogen (nitrate,...
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2021
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Online Access: | https://doi.org/10.5194/bg-18-6031-2021 https://doaj.org/article/2b2436c900474c63ac7d41810a8cc7c9 |
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ftdoajarticles:oai:doaj.org/article:2b2436c900474c63ac7d41810a8cc7c9 2023-05-15T14:05:05+02:00 Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf R. F. Flynn T. G. Bornman J. M. Burger S. Smith K. A. M. Spence S. E. Fawcett 2021-11-01T00:00:00Z https://doi.org/10.5194/bg-18-6031-2021 https://doaj.org/article/2b2436c900474c63ac7d41810a8cc7c9 EN eng Copernicus Publications https://bg.copernicus.org/articles/18/6031/2021/bg-18-6031-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-6031-2021 1726-4170 1726-4189 https://doaj.org/article/2b2436c900474c63ac7d41810a8cc7c9 Biogeosciences, Vol 18, Pp 6031-6059 (2021) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/bg-18-6031-2021 2022-12-31T13:56:38Z The Weddell Sea represents a point of origin in the Southern Ocean where globally important water masses form. Biological activities in Weddell Sea surface waters thus affect large-scale ocean biogeochemistry. During January–February 2019, we measured net primary production (NPP), nitrogen (nitrate, ammonium, urea) uptake, and nitrification in the western Weddell Sea at the Antarctic Peninsula (AP) and Larsen C Ice Shelf (LCIS), in the southwestern Weddell Gyre (WG), and at Fimbul Ice Shelf (FIS) in the south-eastern Weddell Sea. The highest average rates of NPP and greatest nutrient drawdown occurred at LCIS. Here, the phytoplankton community was dominated by colonial Phaeocystis antarctica , with diatoms increasing in abundance later in the season as sea ice melted. At the other stations, NPP was variable, and diatoms known to enhance carbon export (e.g. Thalassiosira spp.) were dominant. Euphotic zone nitrification was always below detection, such that nitrate uptake could be used as a proxy for carbon export potential, which was highest in absolute terms at LCIS and the AP. Surprisingly, the highest f ratios occurred near FIS rather than LCIS (average of 0.73±0.09 versus 0.47±0.08 ). We attribute this unexpected result to partial ammonium inhibition of nitrate uptake at LCIS (where ammonium concentrations were 0.6±0.4 µM , versus 0.05±0.1 µM at FIS), with elevated ammonium resulting from increased heterotrophy following the accumulation of nitrate-fuelled phytoplankton biomass in early summer. Across the Weddell Sea, carbon export appears to be controlled by a combination of physical, chemical, and biological factors, with the highest potential export flux occurring at the ice shelves and lowest in the central WG. Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Antarctica Fimbul Ice Shelf Ice Shelf Ice Shelves Sea ice Southern Ocean Weddell Sea Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean The Antarctic Antarctic Peninsula Weddell Sea Weddell Fimbul Ice Shelf ENVELOPE(-0.500,-0.500,-70.750,-70.750) Biogeosciences 18 22 6031 6059 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 R. F. Flynn T. G. Bornman J. M. Burger S. Smith K. A. M. Spence S. E. Fawcett Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The Weddell Sea represents a point of origin in the Southern Ocean where globally important water masses form. Biological activities in Weddell Sea surface waters thus affect large-scale ocean biogeochemistry. During January–February 2019, we measured net primary production (NPP), nitrogen (nitrate, ammonium, urea) uptake, and nitrification in the western Weddell Sea at the Antarctic Peninsula (AP) and Larsen C Ice Shelf (LCIS), in the southwestern Weddell Gyre (WG), and at Fimbul Ice Shelf (FIS) in the south-eastern Weddell Sea. The highest average rates of NPP and greatest nutrient drawdown occurred at LCIS. Here, the phytoplankton community was dominated by colonial Phaeocystis antarctica , with diatoms increasing in abundance later in the season as sea ice melted. At the other stations, NPP was variable, and diatoms known to enhance carbon export (e.g. Thalassiosira spp.) were dominant. Euphotic zone nitrification was always below detection, such that nitrate uptake could be used as a proxy for carbon export potential, which was highest in absolute terms at LCIS and the AP. Surprisingly, the highest f ratios occurred near FIS rather than LCIS (average of 0.73±0.09 versus 0.47±0.08 ). We attribute this unexpected result to partial ammonium inhibition of nitrate uptake at LCIS (where ammonium concentrations were 0.6±0.4 µM , versus 0.05±0.1 µM at FIS), with elevated ammonium resulting from increased heterotrophy following the accumulation of nitrate-fuelled phytoplankton biomass in early summer. Across the Weddell Sea, carbon export appears to be controlled by a combination of physical, chemical, and biological factors, with the highest potential export flux occurring at the ice shelves and lowest in the central WG. |
format |
Article in Journal/Newspaper |
author |
R. F. Flynn T. G. Bornman J. M. Burger S. Smith K. A. M. Spence S. E. Fawcett |
author_facet |
R. F. Flynn T. G. Bornman J. M. Burger S. Smith K. A. M. Spence S. E. Fawcett |
author_sort |
R. F. Flynn |
title |
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
title_short |
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
title_full |
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
title_fullStr |
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
title_full_unstemmed |
Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf |
title_sort |
summertime productivity and carbon export potential in the weddell sea, with a focus on the waters adjacent to larsen c ice shelf |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/bg-18-6031-2021 https://doaj.org/article/2b2436c900474c63ac7d41810a8cc7c9 |
long_lat |
ENVELOPE(-0.500,-0.500,-70.750,-70.750) |
geographic |
Antarctic Southern Ocean The Antarctic Antarctic Peninsula Weddell Sea Weddell Fimbul Ice Shelf |
geographic_facet |
Antarctic Southern Ocean The Antarctic Antarctic Peninsula Weddell Sea Weddell Fimbul Ice Shelf |
genre |
Antarc* Antarctic Antarctic Peninsula Antarctica Fimbul Ice Shelf Ice Shelf Ice Shelves Sea ice Southern Ocean Weddell Sea |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Antarctica Fimbul Ice Shelf Ice Shelf Ice Shelves Sea ice Southern Ocean Weddell Sea |
op_source |
Biogeosciences, Vol 18, Pp 6031-6059 (2021) |
op_relation |
https://bg.copernicus.org/articles/18/6031/2021/bg-18-6031-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-6031-2021 1726-4170 1726-4189 https://doaj.org/article/2b2436c900474c63ac7d41810a8cc7c9 |
op_doi |
https://doi.org/10.5194/bg-18-6031-2021 |
container_title |
Biogeosciences |
container_volume |
18 |
container_issue |
22 |
container_start_page |
6031 |
op_container_end_page |
6059 |
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1766276716773244928 |