Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf
The concentrations and elemental stoichiometry of particulate and dissolved pools of carbon (C), nitrogen (N), phosphorus (P) and silicon (Si) on the Canadian Beaufort Shelf during summer 2009 (MALINA program) were assessed and compared with those of surface waters provided by the Mackenzie river as...
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2014
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ftdoajarticles:oai:doaj.org/article:2a310cd3f9c1468e9bba41faf6dd3848 2023-05-15T15:44:16+02:00 Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf J.-É. Tremblay P. Raimbault N. Garcia B. Lansard M. Babin J. Gagnon 2014-09-01T00:00:00Z https://doi.org/10.5194/bg-11-4853-2014 https://doaj.org/article/2a310cd3f9c1468e9bba41faf6dd3848 EN eng Copernicus Publications http://www.biogeosciences.net/11/4853/2014/bg-11-4853-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-4853-2014 https://doaj.org/article/2a310cd3f9c1468e9bba41faf6dd3848 Biogeosciences, Vol 11, Iss 17, Pp 4853-4868 (2014) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/bg-11-4853-2014 2022-12-31T14:46:32Z The concentrations and elemental stoichiometry of particulate and dissolved pools of carbon (C), nitrogen (N), phosphorus (P) and silicon (Si) on the Canadian Beaufort Shelf during summer 2009 (MALINA program) were assessed and compared with those of surface waters provided by the Mackenzie river as well as by winter mixing and upwelling of upper halocline waters at the shelf break. Neritic surface waters showed a clear enrichment in dissolved and particulate organic carbon (DOC and POC, respectively), nitrate, total particulate nitrogen (TPN) and dissolved organic nitrogen (DON) originating from the river. Silicate as well as bulk DON and DOC declined in a near-conservative manner away from the delta's outlet, whereas nitrate dropped non-conservatively to very low background concentrations inside the brackish zone. By contrast, the excess of soluble reactive P (SRP) present in oceanic waters declined in a non-conservative manner toward the river outlet, where concentrations were very low and consistent with P shortage in the Mackenzie River. These opposite gradients imply that the admixture of Pacific-derived, SRP-rich water is necessary to allow phytoplankton to use river-derived nitrate and to a lesser extent DON. A coarse budget based on concurrent estimates of primary production shows that river N deliveries support a modest fraction of primary production when considering the entire shelf, due to the ability of phytoplankton to thrive in the subsurface chlorophyll maximum beneath the thin, nitrate-depleted river plume. Away from shallow coastal bays, local elevations in the concentration of primary production and dissolved organic constituents were consistent with upwelling at the shelf break. By contrast with shallow winter mixing, nutrient deliveries by North American rivers and upwelling relax surface communities from N limitation and permit a more extant utilization of the excess SRP entering through the Bering Strait. In this context, increased nitrogen supply by rivers and upwelling potentially alters ... Article in Journal/Newspaper Bering Strait Mackenzie river Directory of Open Access Journals: DOAJ Articles Beaufort Shelf ENVELOPE(-142.500,-142.500,70.000,70.000) Bering Strait Mackenzie River Pacific Biogeosciences 11 17 4853 4868 |
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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 J.-É. Tremblay P. Raimbault N. Garcia B. Lansard M. Babin J. Gagnon Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The concentrations and elemental stoichiometry of particulate and dissolved pools of carbon (C), nitrogen (N), phosphorus (P) and silicon (Si) on the Canadian Beaufort Shelf during summer 2009 (MALINA program) were assessed and compared with those of surface waters provided by the Mackenzie river as well as by winter mixing and upwelling of upper halocline waters at the shelf break. Neritic surface waters showed a clear enrichment in dissolved and particulate organic carbon (DOC and POC, respectively), nitrate, total particulate nitrogen (TPN) and dissolved organic nitrogen (DON) originating from the river. Silicate as well as bulk DON and DOC declined in a near-conservative manner away from the delta's outlet, whereas nitrate dropped non-conservatively to very low background concentrations inside the brackish zone. By contrast, the excess of soluble reactive P (SRP) present in oceanic waters declined in a non-conservative manner toward the river outlet, where concentrations were very low and consistent with P shortage in the Mackenzie River. These opposite gradients imply that the admixture of Pacific-derived, SRP-rich water is necessary to allow phytoplankton to use river-derived nitrate and to a lesser extent DON. A coarse budget based on concurrent estimates of primary production shows that river N deliveries support a modest fraction of primary production when considering the entire shelf, due to the ability of phytoplankton to thrive in the subsurface chlorophyll maximum beneath the thin, nitrate-depleted river plume. Away from shallow coastal bays, local elevations in the concentration of primary production and dissolved organic constituents were consistent with upwelling at the shelf break. By contrast with shallow winter mixing, nutrient deliveries by North American rivers and upwelling relax surface communities from N limitation and permit a more extant utilization of the excess SRP entering through the Bering Strait. In this context, increased nitrogen supply by rivers and upwelling potentially alters ... |
format |
Article in Journal/Newspaper |
author |
J.-É. Tremblay P. Raimbault N. Garcia B. Lansard M. Babin J. Gagnon |
author_facet |
J.-É. Tremblay P. Raimbault N. Garcia B. Lansard M. Babin J. Gagnon |
author_sort |
J.-É. Tremblay |
title |
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
title_short |
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
title_full |
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
title_fullStr |
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
title_full_unstemmed |
Impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the Canadian Beaufort Shelf |
title_sort |
impact of river discharge, upwelling and vertical mixing on the nutrient loading and productivity of the canadian beaufort shelf |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/bg-11-4853-2014 https://doaj.org/article/2a310cd3f9c1468e9bba41faf6dd3848 |
long_lat |
ENVELOPE(-142.500,-142.500,70.000,70.000) |
geographic |
Beaufort Shelf Bering Strait Mackenzie River Pacific |
geographic_facet |
Beaufort Shelf Bering Strait Mackenzie River Pacific |
genre |
Bering Strait Mackenzie river |
genre_facet |
Bering Strait Mackenzie river |
op_source |
Biogeosciences, Vol 11, Iss 17, Pp 4853-4868 (2014) |
op_relation |
http://www.biogeosciences.net/11/4853/2014/bg-11-4853-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-4853-2014 https://doaj.org/article/2a310cd3f9c1468e9bba41faf6dd3848 |
op_doi |
https://doi.org/10.5194/bg-11-4853-2014 |
container_title |
Biogeosciences |
container_volume |
11 |
container_issue |
17 |
container_start_page |
4853 |
op_container_end_page |
4868 |
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1766378570302619648 |