Bottom-up versus top-down control in phytoplankton of the Southern Ocean
Oceanic phytoplankton communities are a mixture of various algal functional groups, all of which are of different sizes, have variable physiologies, and interact differently with disparate herbivores. We suggest that polar plankton communities, and specifically the larger phytoplankton of Southern O...
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ftunivbruxelles:oai:dipot.ulb.ac.be:2013/56882 2023-05-15T13:55:32+02:00 Bottom-up versus top-down control in phytoplankton of the Southern Ocean Smith, Walker O. Jr. Lancelot, Christiane 2004 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/56882 https://dipot.ulb.ac.be/dspace/bitstream/2013/56882/1/2004-AS-16-531-539.pdf en eng uri/info:doi/10.1017/S0954102004002305 uri/info:scp/10944274204 https://dipot.ulb.ac.be/dspace/bitstream/2013/56882/1/2004-AS-16-531-539.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/56882 1 full-text file(s): info:eu-repo/semantics/closedAccess Antarctic science, 16 (4 Océanographie biologique Ecologie antarctic functional group HNLC high nutrient low chlorophyll iron irradiance regulation info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2004 ftunivbruxelles 2022-06-12T20:41:24Z Oceanic phytoplankton communities are a mixture of various algal functional groups, all of which are of different sizes, have variable physiologies, and interact differently with disparate herbivores. We suggest that polar plankton communities, and specifically the larger phytoplankton of Southern Ocean HNLC (high nutrient, low chlorophyll) systems, are controlled primarily by bottom-up processes, but that smaller (pico- and nanoplankton) reach an equilibrium that is set simultaneously by light, iron and grazing by microzooplankton. Thus Southern Ocean phytoplankton conforms to the “ecumenical iron hypothesis”, albeit with the further addition of light as an environmental control. Examples of bottom-up controls include iron availability, irradiance regulation (either by the incident surface irradiance as controlled by season and sea ice cover, or by the effects of vertical turbulence and mixed layer depths), and macronutrient availability (silicic acid and nitrate). While the contribution of various phytoplankton taxa varies spatially and temporally within the Antarctic, we suggest that this is largely due to the specific responses of the important functional groups to the patterns of physical forcing and micronutrient inputs, rather than to changes in controls by small and large grazers. Examples of abiotic and biotic controls are examined from representative regions of the Antarctic, including continental shelf regions and open ocean HNLC systems. Results from models further support our contention that bottom-up control of large forms is paramount in the Southern Ocean, but top-down controls play an important part in regulating the equilibrium standing stocks of smaller taxa. If bottom-up control is indeed universal in the Antarctic, then it has profound implications for the understanding of interannual variability, food web structure, and population dynamics of higher trophic levels in both the present and past Southern Ocean. info:eu-repo/semantics/published The Role of the Southern Ocean in Global ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Science Sea ice Southern Ocean DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Antarctic Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Océanographie biologique Ecologie antarctic functional group HNLC high nutrient low chlorophyll iron irradiance regulation |
spellingShingle |
Océanographie biologique Ecologie antarctic functional group HNLC high nutrient low chlorophyll iron irradiance regulation Smith, Walker O. Jr. Lancelot, Christiane Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
topic_facet |
Océanographie biologique Ecologie antarctic functional group HNLC high nutrient low chlorophyll iron irradiance regulation |
description |
Oceanic phytoplankton communities are a mixture of various algal functional groups, all of which are of different sizes, have variable physiologies, and interact differently with disparate herbivores. We suggest that polar plankton communities, and specifically the larger phytoplankton of Southern Ocean HNLC (high nutrient, low chlorophyll) systems, are controlled primarily by bottom-up processes, but that smaller (pico- and nanoplankton) reach an equilibrium that is set simultaneously by light, iron and grazing by microzooplankton. Thus Southern Ocean phytoplankton conforms to the “ecumenical iron hypothesis”, albeit with the further addition of light as an environmental control. Examples of bottom-up controls include iron availability, irradiance regulation (either by the incident surface irradiance as controlled by season and sea ice cover, or by the effects of vertical turbulence and mixed layer depths), and macronutrient availability (silicic acid and nitrate). While the contribution of various phytoplankton taxa varies spatially and temporally within the Antarctic, we suggest that this is largely due to the specific responses of the important functional groups to the patterns of physical forcing and micronutrient inputs, rather than to changes in controls by small and large grazers. Examples of abiotic and biotic controls are examined from representative regions of the Antarctic, including continental shelf regions and open ocean HNLC systems. Results from models further support our contention that bottom-up control of large forms is paramount in the Southern Ocean, but top-down controls play an important part in regulating the equilibrium standing stocks of smaller taxa. If bottom-up control is indeed universal in the Antarctic, then it has profound implications for the understanding of interannual variability, food web structure, and population dynamics of higher trophic levels in both the present and past Southern Ocean. info:eu-repo/semantics/published The Role of the Southern Ocean in Global ... |
format |
Article in Journal/Newspaper |
author |
Smith, Walker O. Jr. Lancelot, Christiane |
author_facet |
Smith, Walker O. Jr. Lancelot, Christiane |
author_sort |
Smith, Walker O. Jr. |
title |
Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
title_short |
Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
title_full |
Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
title_fullStr |
Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
title_full_unstemmed |
Bottom-up versus top-down control in phytoplankton of the Southern Ocean |
title_sort |
bottom-up versus top-down control in phytoplankton of the southern ocean |
publishDate |
2004 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/56882 https://dipot.ulb.ac.be/dspace/bitstream/2013/56882/1/2004-AS-16-531-539.pdf |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctic Science Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Science Sea ice Southern Ocean |
op_source |
Antarctic science, 16 (4 |
op_relation |
uri/info:doi/10.1017/S0954102004002305 uri/info:scp/10944274204 https://dipot.ulb.ac.be/dspace/bitstream/2013/56882/1/2004-AS-16-531-539.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/56882 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/closedAccess |
_version_ |
1766262207080824832 |