Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean
We examined phytoplankton community responses to natural iron fertilisation at 32 sites over and downstream from the Kerguelen Plateau in the Southern Ocean during the austral spring bloom in October–November 2011. The community structure was estimated from chemical and isotopic measurements (partic...
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2015
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ftdoajarticles:oai:doaj.org/article:f87893b7016141e79814e45242e8c3e9 2023-05-15T18:25:16+02:00 Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean T. W. Trull D. M. Davies F. Dehairs A.-J. Cavagna M. Lasbleiz E. C. Laurenceau-Cornec F. d'Ovidio F. Planchon K. Leblanc B. Quéguiner S. Blain 2015-02-01T00:00:00Z https://doi.org/10.5194/bg-12-1029-2015 https://doaj.org/article/f87893b7016141e79814e45242e8c3e9 EN eng Copernicus Publications http://www.biogeosciences.net/12/1029/2015/bg-12-1029-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-1029-2015 https://doaj.org/article/f87893b7016141e79814e45242e8c3e9 Biogeosciences, Vol 12, Iss 4, Pp 1029-1056 (2015) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/bg-12-1029-2015 2022-12-30T21:21:26Z We examined phytoplankton community responses to natural iron fertilisation at 32 sites over and downstream from the Kerguelen Plateau in the Southern Ocean during the austral spring bloom in October–November 2011. The community structure was estimated from chemical and isotopic measurements (particulate organic carbon – POC; 13 C-POC; particulate nitrogen – PN; 15 N-PN; and biogenic silica – BSi) on size-fractionated samples from surface waters (300, 210, 50, 20, 5, and 1 μm fractions). Higher values of 13 C-POC (vs. co-located 13 C values for dissolved inorganic carbon – DIC) were taken as indicative of faster growth rates and higher values of 15 N-PN (vs. co-located 15 N-NO 3 source values) as indicative of greater nitrate use (rather than ammonium use, i.e. higher f ratios). Community responses varied in relation to both regional circulation and the advance of the bloom. Iron-fertilised waters over the plateau developed dominance by very large diatoms (50–210 μm) with high BSi / POC ratios, high growth rates, and significant ammonium recycling (lower f ratios) as biomass built up. In contrast, downstream polar frontal waters with a similar or higher iron supply were dominated by smaller diatoms (20–50 μm) and exhibited greater ammonium recycling. Stations in a deep-water bathymetrically trapped recirculation south of the polar front with lower iron levels showed the large-cell dominance observed on the plateau but much less biomass. Comparison of these communities to surface water nitrate (and silicate) depletions as a proxy for export shows that the low-biomass recirculation feature had exported similar amounts of nitrogen to the high-biomass blooms over the plateau and north of the polar front. This suggests that early spring trophodynamic and export responses differed between regions with persistent low levels vs. intermittent high levels of iron fertilisation. Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Austral Kerguelen Biogeosciences 12 4 1029 1056 |
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 T. W. Trull D. M. Davies F. Dehairs A.-J. Cavagna M. Lasbleiz E. C. Laurenceau-Cornec F. d'Ovidio F. Planchon K. Leblanc B. Quéguiner S. Blain Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
We examined phytoplankton community responses to natural iron fertilisation at 32 sites over and downstream from the Kerguelen Plateau in the Southern Ocean during the austral spring bloom in October–November 2011. The community structure was estimated from chemical and isotopic measurements (particulate organic carbon – POC; 13 C-POC; particulate nitrogen – PN; 15 N-PN; and biogenic silica – BSi) on size-fractionated samples from surface waters (300, 210, 50, 20, 5, and 1 μm fractions). Higher values of 13 C-POC (vs. co-located 13 C values for dissolved inorganic carbon – DIC) were taken as indicative of faster growth rates and higher values of 15 N-PN (vs. co-located 15 N-NO 3 source values) as indicative of greater nitrate use (rather than ammonium use, i.e. higher f ratios). Community responses varied in relation to both regional circulation and the advance of the bloom. Iron-fertilised waters over the plateau developed dominance by very large diatoms (50–210 μm) with high BSi / POC ratios, high growth rates, and significant ammonium recycling (lower f ratios) as biomass built up. In contrast, downstream polar frontal waters with a similar or higher iron supply were dominated by smaller diatoms (20–50 μm) and exhibited greater ammonium recycling. Stations in a deep-water bathymetrically trapped recirculation south of the polar front with lower iron levels showed the large-cell dominance observed on the plateau but much less biomass. Comparison of these communities to surface water nitrate (and silicate) depletions as a proxy for export shows that the low-biomass recirculation feature had exported similar amounts of nitrogen to the high-biomass blooms over the plateau and north of the polar front. This suggests that early spring trophodynamic and export responses differed between regions with persistent low levels vs. intermittent high levels of iron fertilisation. |
format |
Article in Journal/Newspaper |
author |
T. W. Trull D. M. Davies F. Dehairs A.-J. Cavagna M. Lasbleiz E. C. Laurenceau-Cornec F. d'Ovidio F. Planchon K. Leblanc B. Quéguiner S. Blain |
author_facet |
T. W. Trull D. M. Davies F. Dehairs A.-J. Cavagna M. Lasbleiz E. C. Laurenceau-Cornec F. d'Ovidio F. Planchon K. Leblanc B. Quéguiner S. Blain |
author_sort |
T. W. Trull |
title |
Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
title_short |
Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
title_full |
Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
title_fullStr |
Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
title_full_unstemmed |
Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean |
title_sort |
chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the kerguelen plateau in the southern ocean |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/bg-12-1029-2015 https://doaj.org/article/f87893b7016141e79814e45242e8c3e9 |
geographic |
Southern Ocean Austral Kerguelen |
geographic_facet |
Southern Ocean Austral Kerguelen |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Biogeosciences, Vol 12, Iss 4, Pp 1029-1056 (2015) |
op_relation |
http://www.biogeosciences.net/12/1029/2015/bg-12-1029-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-1029-2015 https://doaj.org/article/f87893b7016141e79814e45242e8c3e9 |
op_doi |
https://doi.org/10.5194/bg-12-1029-2015 |
container_title |
Biogeosciences |
container_volume |
12 |
container_issue |
4 |
container_start_page |
1029 |
op_container_end_page |
1056 |
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1766206578978979840 |