Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean

Handle URI:
http://hdl.handle.net/10754/555782
Title:
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean
Authors:
Krafft, BA; Skaret, G; Knutsen, T; Melle, W; Klevjer, Thor; Søiland, H
Abstract:
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.
KAUST Department:
Red Sea Research Center (RSRC)
Citation:
Antarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean 2012, 465:69 Marine Ecology Progress Series
Publisher:
Inter-Research Science Center
Journal:
Marine Ecology Progress Series
Issue Date:
28-Sep-2012
DOI:
10.3354/meps09876
Type:
Article
ISSN:
0171-8630; 1616-1599
Additional Links:
http://www.int-res.com/abstracts/meps/v465/p69-83/
Appears in Collections:
Articles; Red Sea Research Center (RSRC); Red Sea Research Center (RSRC)

Full metadata record

DC FieldValue Language
dc.contributor.authorKrafft, BAen
dc.contributor.authorSkaret, Gen
dc.contributor.authorKnutsen, Ten
dc.contributor.authorMelle, Wen
dc.contributor.authorKlevjer, Thoren
dc.contributor.authorSøiland, Hen
dc.date.accessioned2015-05-26T07:27:45Zen
dc.date.available2015-05-26T07:27:45Zen
dc.date.issued2012-09-28en
dc.identifier.citationAntarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Ocean 2012, 465:69 Marine Ecology Progress Seriesen
dc.identifier.issn0171-8630en
dc.identifier.issn1616-1599en
dc.identifier.doi10.3354/meps09876en
dc.identifier.urihttp://hdl.handle.net/10754/555782en
dc.description.abstractKnowledge 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.en
dc.publisherInter-Research Science Centeren
dc.relation.urlhttp://www.int-res.com/abstracts/meps/v465/p69-83/en
dc.rightsArchived with thanks to Marine Ecology Progress Seriesen
dc.subjectEuphausia superbaen
dc.subjectAggregationen
dc.subjectAcousticsen
dc.subjectSwarmen
dc.subjectBouvetøyaen
dc.titleAntarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Oceanen
dc.typeArticleen
dc.contributor.departmentRed Sea Research Center (RSRC)en
dc.identifier.journalMarine Ecology Progress Seriesen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionInstitute of Marine Research, 5870 Bergen, Norwayen
dc.contributor.institutionDepartment of Biology, University of Oslo, 0316 Oslo, Norwayen
kaust.authorKlevjer, Thor Aleksanderen
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