Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters
During the 1999 Marion Island Oceanographic Survey (MIOS 4) in late austral summer, a northbound and reciprocal southbound transect were taken along the Southwest Indian and Madagascar Ridge, between the Prince Edward Islands and 31° S. The sections crossed a number of major fronts and smaller mesos...
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2011
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00027848 2023-05-15T17:10:21+02:00 Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters Thomalla, S. J. Waldron, H. N. Lucas, M. I. Read, J. F. Ansorge, I. J. Pakhomov, E. 2011-02 electronic https://doi.org/10.5194/os-7-113-2011 https://noa.gwlb.de/receive/cop_mods_00027848 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00027803/os-7-113-2011.pdf https://os.copernicus.org/articles/7/113/2011/os-7-113-2011.pdf eng eng Copernicus Publications Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-7-113-2011 https://noa.gwlb.de/receive/cop_mods_00027848 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00027803/os-7-113-2011.pdf https://os.copernicus.org/articles/7/113/2011/os-7-113-2011.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2011 ftnonlinearchiv https://doi.org/10.5194/os-7-113-2011 2022-02-08T22:48:29Z During the 1999 Marion Island Oceanographic Survey (MIOS 4) in late austral summer, a northbound and reciprocal southbound transect were taken along the Southwest Indian and Madagascar Ridge, between the Prince Edward Islands and 31° S. The sections crossed a number of major fronts and smaller mesoscale features and covered a wide productivity spectrum from subtropical to subantarctic waters. Associated with the physical survey were measurements of size fractionated chlorophyll, nutrients and nitrogen (NO3, NH4 and urea) uptake rates. Subtropical waters were characterised by low chlorophyll concentrations (max = 0.27.3 mg m−3 dominated by pico-phytoplankton cells (> 81%) and very low f-ratios (< 0.1), indicative of productivity based almost entirely on recycled ammonium and urea. Micro-phytoplankton growth was limited by the availability of NO3 (< 0.5 mmol m−3 and Si(OH)4 (< 1.5 mmol m−3 through strong vertical stratification preventing the upward flux of nutrients into the euphotic zone. Biomass accumulation of small cells was likely controlled by micro-zooplankton grazing. In subantarctic waters, total chlorophyll concentrations increased (max = 0.74 mg m−3 relative to the subtropical waters and larger cells became more prevalent, however smaller phytoplankton cells and low f-ratios (< 0.14) still dominated, despite sufficient NO3 availability. The results from this study favour Si(OH)4 limitation, light-limited deep mixing and likely Fe deficiency as the dominant mechanisms controlling significant new production by micro-phytoplankton. The percentage of micro-phytoplankton cells and rates of new production did however increase at oceanic frontal regions (58.6% and 11.22%, respectively), and in the region of the Prince Edward archipelago (61.4% and 14.16%, respectively). Here, water column stabilization and local Fe-enrichment are thought to stimulate phytoplankton growth rates. Open ocean regions such as these provide important areas for local but significant particulate organic carbon export and biological CO2 draw-down in an overall high nutrient low chlorophyll Southern Ocean. Article in Journal/Newspaper Marion Island Prince Edward Islands Southern Ocean Niedersächsisches Online-Archiv NOA Austral Indian Southern Ocean Ocean Science 7 1 113 127 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
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English |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Thomalla, S. J. Waldron, H. N. Lucas, M. I. Read, J. F. Ansorge, I. J. Pakhomov, E. Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
topic_facet |
article Verlagsveröffentlichung |
description |
During the 1999 Marion Island Oceanographic Survey (MIOS 4) in late austral summer, a northbound and reciprocal southbound transect were taken along the Southwest Indian and Madagascar Ridge, between the Prince Edward Islands and 31° S. The sections crossed a number of major fronts and smaller mesoscale features and covered a wide productivity spectrum from subtropical to subantarctic waters. Associated with the physical survey were measurements of size fractionated chlorophyll, nutrients and nitrogen (NO3, NH4 and urea) uptake rates. Subtropical waters were characterised by low chlorophyll concentrations (max = 0.27.3 mg m−3 dominated by pico-phytoplankton cells (> 81%) and very low f-ratios (< 0.1), indicative of productivity based almost entirely on recycled ammonium and urea. Micro-phytoplankton growth was limited by the availability of NO3 (< 0.5 mmol m−3 and Si(OH)4 (< 1.5 mmol m−3 through strong vertical stratification preventing the upward flux of nutrients into the euphotic zone. Biomass accumulation of small cells was likely controlled by micro-zooplankton grazing. In subantarctic waters, total chlorophyll concentrations increased (max = 0.74 mg m−3 relative to the subtropical waters and larger cells became more prevalent, however smaller phytoplankton cells and low f-ratios (< 0.14) still dominated, despite sufficient NO3 availability. The results from this study favour Si(OH)4 limitation, light-limited deep mixing and likely Fe deficiency as the dominant mechanisms controlling significant new production by micro-phytoplankton. The percentage of micro-phytoplankton cells and rates of new production did however increase at oceanic frontal regions (58.6% and 11.22%, respectively), and in the region of the Prince Edward archipelago (61.4% and 14.16%, respectively). Here, water column stabilization and local Fe-enrichment are thought to stimulate phytoplankton growth rates. Open ocean regions such as these provide important areas for local but significant particulate organic carbon export and biological CO2 draw-down in an overall high nutrient low chlorophyll Southern Ocean. |
format |
Article in Journal/Newspaper |
author |
Thomalla, S. J. Waldron, H. N. Lucas, M. I. Read, J. F. Ansorge, I. J. Pakhomov, E. |
author_facet |
Thomalla, S. J. Waldron, H. N. Lucas, M. I. Read, J. F. Ansorge, I. J. Pakhomov, E. |
author_sort |
Thomalla, S. J. |
title |
Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
title_short |
Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
title_full |
Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
title_fullStr |
Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
title_full_unstemmed |
Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters |
title_sort |
phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and southern ocean waters |
publisher |
Copernicus Publications |
publishDate |
2011 |
url |
https://doi.org/10.5194/os-7-113-2011 https://noa.gwlb.de/receive/cop_mods_00027848 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00027803/os-7-113-2011.pdf https://os.copernicus.org/articles/7/113/2011/os-7-113-2011.pdf |
geographic |
Austral Indian Southern Ocean |
geographic_facet |
Austral Indian Southern Ocean |
genre |
Marion Island Prince Edward Islands Southern Ocean |
genre_facet |
Marion Island Prince Edward Islands Southern Ocean |
op_relation |
Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-7-113-2011 https://noa.gwlb.de/receive/cop_mods_00027848 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00027803/os-7-113-2011.pdf https://os.copernicus.org/articles/7/113/2011/os-7-113-2011.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-7-113-2011 |
container_title |
Ocean Science |
container_volume |
7 |
container_issue |
1 |
container_start_page |
113 |
op_container_end_page |
127 |
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1766066941552754688 |