Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean
Natural iron fertilisation from Southern Ocean islands results in high primary production and phytoplankton biomass accumulations readily visible in satellite ocean colour observations. These images reveal great spatial complexity with highly varying concentrations of chlorophyll, presumably reflect...
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ftdoajarticles:oai:doaj.org/article:01f35e1c666a4d5ea70bf1c60cb44404 2023-05-15T14:06:26+02:00 Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean M. Grenier A. Della Penna T. W. Trull 2015-05-01T00:00:00Z https://doi.org/10.5194/bg-12-2707-2015 https://doaj.org/article/01f35e1c666a4d5ea70bf1c60cb44404 EN eng Copernicus Publications http://www.biogeosciences.net/12/2707/2015/bg-12-2707-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-2707-2015 https://doaj.org/article/01f35e1c666a4d5ea70bf1c60cb44404 Biogeosciences, Vol 12, Iss 9, Pp 2707-2735 (2015) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/bg-12-2707-2015 2022-12-31T16:13:59Z Natural iron fertilisation from Southern Ocean islands results in high primary production and phytoplankton biomass accumulations readily visible in satellite ocean colour observations. These images reveal great spatial complexity with highly varying concentrations of chlorophyll, presumably reflecting both variations in iron supply and conditions favouring phytoplankton accumulation. To examine the second aspect, in particular the influences of variations in temperature and mixed layer depth, we deployed four autonomous profiling floats in the Antarctic Circumpolar Current near the Kerguelen Plateau in the Indian sector of the Southern Ocean. Each "bio-profiler" measured more than 250 profiles of temperature ( T ), salinity ( S ), dissolved oxygen, chlorophyll a (Chl a ) fluorescence, and particulate backscattering ( b bp ) in the top 300 m of the water column, sampling up to 5 profiles per day along meandering trajectories extending up to 1000 km. Comparison of surface Chl a estimates (analogous to values from satellite images) with total water column inventories revealed largely linear relationships, suggesting that these images provide credible information on total and not just surface biomass spatial distributions. However, they also showed that physical mixed layer depths are often not a reliable guide to biomass distributions. Regions of very high Chl a accumulation (1.5–10 μg L −1 ) were associated predominantly with a narrow T – S class of surface waters. In contrast, waters with only moderate Chl a enrichments (0.5–1.5 μg L −1 ) displayed no clear correlation with specific water properties, including no dependence on mixed layer depth or the intensity of stratification. Geostrophic trajectory analysis suggests that both these observations can be explained if the main determinant of biomass in a given water parcel is the time since leaving the Kerguelen Plateau. One float became trapped in a cyclonic eddy, allowing temporal evaluation of the water column in early autumn. During this period, decreasing ... Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Indian Kerguelen Southern Ocean The Antarctic Biogeosciences 12 9 2707 2735 |
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 M. Grenier A. Della Penna T. W. Trull Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Natural iron fertilisation from Southern Ocean islands results in high primary production and phytoplankton biomass accumulations readily visible in satellite ocean colour observations. These images reveal great spatial complexity with highly varying concentrations of chlorophyll, presumably reflecting both variations in iron supply and conditions favouring phytoplankton accumulation. To examine the second aspect, in particular the influences of variations in temperature and mixed layer depth, we deployed four autonomous profiling floats in the Antarctic Circumpolar Current near the Kerguelen Plateau in the Indian sector of the Southern Ocean. Each "bio-profiler" measured more than 250 profiles of temperature ( T ), salinity ( S ), dissolved oxygen, chlorophyll a (Chl a ) fluorescence, and particulate backscattering ( b bp ) in the top 300 m of the water column, sampling up to 5 profiles per day along meandering trajectories extending up to 1000 km. Comparison of surface Chl a estimates (analogous to values from satellite images) with total water column inventories revealed largely linear relationships, suggesting that these images provide credible information on total and not just surface biomass spatial distributions. However, they also showed that physical mixed layer depths are often not a reliable guide to biomass distributions. Regions of very high Chl a accumulation (1.5–10 μg L −1 ) were associated predominantly with a narrow T – S class of surface waters. In contrast, waters with only moderate Chl a enrichments (0.5–1.5 μg L −1 ) displayed no clear correlation with specific water properties, including no dependence on mixed layer depth or the intensity of stratification. Geostrophic trajectory analysis suggests that both these observations can be explained if the main determinant of biomass in a given water parcel is the time since leaving the Kerguelen Plateau. One float became trapped in a cyclonic eddy, allowing temporal evaluation of the water column in early autumn. During this period, decreasing ... |
format |
Article in Journal/Newspaper |
author |
M. Grenier A. Della Penna T. W. Trull |
author_facet |
M. Grenier A. Della Penna T. W. Trull |
author_sort |
M. Grenier |
title |
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
title_short |
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
title_full |
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
title_fullStr |
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
title_full_unstemmed |
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean |
title_sort |
autonomous profiling float observations of the high-biomass plume downstream of the kerguelen plateau in the southern ocean |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/bg-12-2707-2015 https://doaj.org/article/01f35e1c666a4d5ea70bf1c60cb44404 |
geographic |
Antarctic Indian Kerguelen Southern Ocean The Antarctic |
geographic_facet |
Antarctic Indian Kerguelen Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Biogeosciences, Vol 12, Iss 9, Pp 2707-2735 (2015) |
op_relation |
http://www.biogeosciences.net/12/2707/2015/bg-12-2707-2015.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-12-2707-2015 https://doaj.org/article/01f35e1c666a4d5ea70bf1c60cb44404 |
op_doi |
https://doi.org/10.5194/bg-12-2707-2015 |
container_title |
Biogeosciences |
container_volume |
12 |
container_issue |
9 |
container_start_page |
2707 |
op_container_end_page |
2735 |
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1766278146801270784 |