Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer
As part of the Bonus-GoodHope (BGH) campaign, 15 N-labelled nitrate, ammonium and urea uptake measurements were made along the BGH transect from Cape Town to ~60° S in late austral summer, 2008. Our results are categorised according to distinct hydrographic regions defined by oceanic fronts and open...
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ftdoajarticles:oai:doaj.org/article:7ec5c0269f3a4036a7c1ac78ff63e454 2023-05-15T14:05:02+02:00 Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer W. R. Joubert S. J. Thomalla H. N. Waldron M. I. Lucas M. Boye F. A. C. Le Moigne F. Planchon S. Speich 2011-10-01T00:00:00Z https://doi.org/10.5194/bg-8-2947-2011 https://doaj.org/article/7ec5c0269f3a4036a7c1ac78ff63e454 EN eng Copernicus Publications http://www.biogeosciences.net/8/2947/2011/bg-8-2947-2011.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-8-2947-2011 1726-4170 1726-4189 https://doaj.org/article/7ec5c0269f3a4036a7c1ac78ff63e454 Biogeosciences, Vol 8, Iss 10, Pp 2947-2959 (2011) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2011 ftdoajarticles https://doi.org/10.5194/bg-8-2947-2011 2022-12-31T14:43:22Z As part of the Bonus-GoodHope (BGH) campaign, 15 N-labelled nitrate, ammonium and urea uptake measurements were made along the BGH transect from Cape Town to ~60° S in late austral summer, 2008. Our results are categorised according to distinct hydrographic regions defined by oceanic fronts and open ocean zones. High regenerated nitrate uptake rate in the oligotrophic Subtropical Zone (STZ) resulted in low f -ratios ( f = 0.2) with nitrogen uptake being dominated by ρurea, which contributed up to 70 % of total nitrogen uptake. Size fractionated chlorophyll data showed that the greatest contribution (>50 %) of picophytoplankton (<2 μm) were found in the STZ, consistent with a community based on regenerated production. The Subantarctic Zone (SAZ) showed the greatest total integrated nitrogen uptake (10.3 mmol m −2 d −1 ), mainly due to enhanced nutrient supply within an anticyclonic eddy observed in this region. A decrease in the contribution of smaller size classes to the phytoplankton community was observed with increasing latitude, concurrent with a decrease in the contribution of regenerated production. Higher f -ratios observed in the SAZ ( f = 0.49), Polar Frontal Zone ( f = 0.41) and Antarctic Zone ( f = 0.45) relative to the STZ ( f = 0.24), indicate a higher contribution of NO 3 − -uptake relative to total nitrogen and potentially higher export production. High ambient regenerated nutrient concentrations are indicative of active regeneration processes throughout the transect and ascribed to late summer season sampling. Higher depth integrated uptake rates also correspond with higher surface iron concentrations. No clear correlation was observed between carbon export estimates derived from new production and 234 Th flux. In addition, export derived from 15 N estimates were 2–20 times greater than those based on 234 Th flux. Variability in the magnitude of export is likely due to intrinsically different methods, compounded by differences in integration time scales for the two proxies of carbon export. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean Austral Biogeosciences 8 10 2947 2959 |
institution |
Open Polar |
collection |
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 W. R. Joubert S. J. Thomalla H. N. Waldron M. I. Lucas M. Boye F. A. C. Le Moigne F. Planchon S. Speich Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
As part of the Bonus-GoodHope (BGH) campaign, 15 N-labelled nitrate, ammonium and urea uptake measurements were made along the BGH transect from Cape Town to ~60° S in late austral summer, 2008. Our results are categorised according to distinct hydrographic regions defined by oceanic fronts and open ocean zones. High regenerated nitrate uptake rate in the oligotrophic Subtropical Zone (STZ) resulted in low f -ratios ( f = 0.2) with nitrogen uptake being dominated by ρurea, which contributed up to 70 % of total nitrogen uptake. Size fractionated chlorophyll data showed that the greatest contribution (>50 %) of picophytoplankton (<2 μm) were found in the STZ, consistent with a community based on regenerated production. The Subantarctic Zone (SAZ) showed the greatest total integrated nitrogen uptake (10.3 mmol m −2 d −1 ), mainly due to enhanced nutrient supply within an anticyclonic eddy observed in this region. A decrease in the contribution of smaller size classes to the phytoplankton community was observed with increasing latitude, concurrent with a decrease in the contribution of regenerated production. Higher f -ratios observed in the SAZ ( f = 0.49), Polar Frontal Zone ( f = 0.41) and Antarctic Zone ( f = 0.45) relative to the STZ ( f = 0.24), indicate a higher contribution of NO 3 − -uptake relative to total nitrogen and potentially higher export production. High ambient regenerated nutrient concentrations are indicative of active regeneration processes throughout the transect and ascribed to late summer season sampling. Higher depth integrated uptake rates also correspond with higher surface iron concentrations. No clear correlation was observed between carbon export estimates derived from new production and 234 Th flux. In addition, export derived from 15 N estimates were 2–20 times greater than those based on 234 Th flux. Variability in the magnitude of export is likely due to intrinsically different methods, compounded by differences in integration time scales for the two proxies of carbon export. |
format |
Article in Journal/Newspaper |
author |
W. R. Joubert S. J. Thomalla H. N. Waldron M. I. Lucas M. Boye F. A. C. Le Moigne F. Planchon S. Speich |
author_facet |
W. R. Joubert S. J. Thomalla H. N. Waldron M. I. Lucas M. Boye F. A. C. Le Moigne F. Planchon S. Speich |
author_sort |
W. R. Joubert |
title |
Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
title_short |
Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
title_full |
Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
title_fullStr |
Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
title_full_unstemmed |
Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer |
title_sort |
nitrogen uptake by phytoplankton in the atlantic sector of the southern ocean during late austral summer |
publisher |
Copernicus Publications |
publishDate |
2011 |
url |
https://doi.org/10.5194/bg-8-2947-2011 https://doaj.org/article/7ec5c0269f3a4036a7c1ac78ff63e454 |
geographic |
Antarctic Southern Ocean Austral |
geographic_facet |
Antarctic Southern Ocean Austral |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Biogeosciences, Vol 8, Iss 10, Pp 2947-2959 (2011) |
op_relation |
http://www.biogeosciences.net/8/2947/2011/bg-8-2947-2011.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-8-2947-2011 1726-4170 1726-4189 https://doaj.org/article/7ec5c0269f3a4036a7c1ac78ff63e454 |
op_doi |
https://doi.org/10.5194/bg-8-2947-2011 |
container_title |
Biogeosciences |
container_volume |
8 |
container_issue |
10 |
container_start_page |
2947 |
op_container_end_page |
2959 |
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1766276664845664256 |