Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean
Knowledge about swarm dynamics and underlying causes is essential to understand the ecology and distribution of Antarctic krill Euphausia superba. We collected acoustic data and key environmental data continuously across extensive gradients in the little-studied Southeast Atlantic sector of the Sout...
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Online Access: | http://hdl.handle.net/11250/109230 https://doi.org/10.3354/meps09876 |
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ftimr:oai:imr.brage.unit.no:11250/109230 2023-05-15T13:44:00+02:00 Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean Krafft, Bjørn A. Skaret, Georg Knutsen, Tor Melle, Webjørn Klevjer, Thor A. Søiland, Henrik 2012-09-28 application/pdf http://hdl.handle.net/11250/109230 https://doi.org/10.3354/meps09876 eng eng Inter-Research http://hdl.handle.net/11250/109230 http://dx.doi.org/10.3354/meps09876 69-83 465 Marine Ecology Progress Series antarctic krill krill acoustics akustikk VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 Journal article Peer reviewed 2012 ftimr https://doi.org/10.3354/meps09876 2021-09-23T20:15:22Z Knowledge about swarm dynamics and underlying causes is essential to understand the ecology and distribution of Antarctic krill Euphausia superba. We collected acoustic data and key environmental data continuously across extensive gradients in the little-studied Southeast Atlantic sector of the Southern Ocean. A total of 4791 krill swarms with swarm descriptors including swarm height and length, packing density, swimming depth and inter-swarm distance were extracted. Through multivariate statistics, swarms were categorized into 4 groups. Group 2 swarms were largest (median length 108 m and thickness 18 m), whereas swarms in both Groups 1 and 4 were on average small, but differed markedly in depth distribution (median: 52 m for Group 1 vs. 133 m for Group 4). There was a strong spatial autocorrelation in the occurrence of swarms, and an autologistic regression model found no prediction of swarm occurrence from environmental variables for any of the Groups 1, 2 or 4. Probability of occurrence of Group 3 swarms, however, increased with increasing depth and temperature. Group 3 was the most distinctive swarm group with an order of magnitude higher packing density (median: 226 ind. m−3) than swarms from any of the other groups and about twice the distance to nearest neighbor swarm (median: 493 m). The majority of the krill were present in Group 3 swarms, and the absence of association with hydrographic or topographic concentrating mechanisms strongly suggests that these swarms aggregate through their own locomotion, possibly associated with migration. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Euphausia superba Southern Ocean Institute for Marine Research: Brage IMR Antarctic Southern Ocean Marine Ecology Progress Series 465 69 83 |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
antarctic krill krill acoustics akustikk VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 |
spellingShingle |
antarctic krill krill acoustics akustikk VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 Krafft, Bjørn A. Skaret, Georg Knutsen, Tor Melle, Webjørn Klevjer, Thor A. Søiland, Henrik Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
topic_facet |
antarctic krill krill acoustics akustikk VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 |
description |
Knowledge about swarm dynamics and underlying causes is essential to understand the ecology and distribution of Antarctic krill Euphausia superba. We collected acoustic data and key environmental data continuously across extensive gradients in the little-studied Southeast Atlantic sector of the Southern Ocean. A total of 4791 krill swarms with swarm descriptors including swarm height and length, packing density, swimming depth and inter-swarm distance were extracted. Through multivariate statistics, swarms were categorized into 4 groups. Group 2 swarms were largest (median length 108 m and thickness 18 m), whereas swarms in both Groups 1 and 4 were on average small, but differed markedly in depth distribution (median: 52 m for Group 1 vs. 133 m for Group 4). There was a strong spatial autocorrelation in the occurrence of swarms, and an autologistic regression model found no prediction of swarm occurrence from environmental variables for any of the Groups 1, 2 or 4. Probability of occurrence of Group 3 swarms, however, increased with increasing depth and temperature. Group 3 was the most distinctive swarm group with an order of magnitude higher packing density (median: 226 ind. m−3) than swarms from any of the other groups and about twice the distance to nearest neighbor swarm (median: 493 m). The majority of the krill were present in Group 3 swarms, and the absence of association with hydrographic or topographic concentrating mechanisms strongly suggests that these swarms aggregate through their own locomotion, possibly associated with migration. |
format |
Article in Journal/Newspaper |
author |
Krafft, Bjørn A. Skaret, Georg Knutsen, Tor Melle, Webjørn Klevjer, Thor A. Søiland, Henrik |
author_facet |
Krafft, Bjørn A. Skaret, Georg Knutsen, Tor Melle, Webjørn Klevjer, Thor A. Søiland, Henrik |
author_sort |
Krafft, Bjørn A. |
title |
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
title_short |
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
title_full |
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
title_fullStr |
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
title_full_unstemmed |
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean |
title_sort |
antarctic krill swarm characteristics in the southeast atlantic sector of the southern ocean |
publisher |
Inter-Research |
publishDate |
2012 |
url |
http://hdl.handle.net/11250/109230 https://doi.org/10.3354/meps09876 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Antarctic Krill Euphausia superba Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Krill Euphausia superba Southern Ocean |
op_source |
69-83 465 Marine Ecology Progress Series |
op_relation |
http://hdl.handle.net/11250/109230 http://dx.doi.org/10.3354/meps09876 |
op_doi |
https://doi.org/10.3354/meps09876 |
container_title |
Marine Ecology Progress Series |
container_volume |
465 |
container_start_page |
69 |
op_container_end_page |
83 |
_version_ |
1766195799075586048 |