Variability and predictability of Antarctic krill swarm structure
Swarming is a fundamental part of the life of Euphausia superba, yet we still know very little about what drives the considerable variability in swarm shape, size and biomass. We examined swarms across the Scotia Sea in January and February 2003 using a Simrad EK60 (38 and 120 kHz) echosounder, conc...
Published in: | Deep Sea Research Part I: Oceanographic Research Papers |
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ftnerc:oai:nora.nerc.ac.uk:11310 2023-05-15T13:45:10+02:00 Variability and predictability of Antarctic krill swarm structure Tarling, Geraint A. Klevjer, Thor Fielding, Sophie Watkins, Jon Atkinson, Angus Murphy, Eugene Korb, Rebecca Whitehouse, Mick Leaper, Russell 2009 http://nora.nerc.ac.uk/id/eprint/11310/ http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VGB-4WTRS81-1-R&_cdi=6034&_user=1773399&_orig=browse&_coverDate=11%2F30%2F2009&_sk=999439988&view=c&wchp=dGLbVzz-zSkWb&md5=c40f22bae01a938bb6bfbc18df328fcc&ie=/sdarticle.pdf unknown Elsevier Tarling, Geraint A. orcid:0000-0002-3753-5899 Klevjer, Thor; Fielding, Sophie orcid:0000-0002-3152-4742 Watkins, Jon; Atkinson, Angus; Murphy, Eugene orcid:0000-0002-7369-9196 Korb, Rebecca; Whitehouse, Mick; Leaper, Russell. 2009 Variability and predictability of Antarctic krill swarm structure. Deep-Sea Research Part I, 56 (11). 1994-2012. https://doi.org/10.1016/j.dsr.2009.07.004 <https://doi.org/10.1016/j.dsr.2009.07.004> Marine Sciences Zoology Ecology and Environment Publication - Article PeerReviewed 2009 ftnerc https://doi.org/10.1016/j.dsr.2009.07.004 2023-02-04T19:27:17Z Swarming is a fundamental part of the life of Euphausia superba, yet we still know very little about what drives the considerable variability in swarm shape, size and biomass. We examined swarms across the Scotia Sea in January and February 2003 using a Simrad EK60 (38 and 120 kHz) echosounder, concurrent with net sampling. The acoustic data were analysed through applying a swarm-identification algorithm and then filtering out all non-krill targets. The area, length, height, depth, packing-concentration and inter-swarm distance of 4525 swarms was derived by this method. Hierarchical clustering revealed 2 principal swarm types, which differed in both their dimensions and packing-concentrations. Type 1 swarms were generally small (<50 m long) and were not very tightly packed (<10 in.m(-3)), whereas type 2 swarms were an order of magnitude larger and had packing concentrations up to 10 times greater. Further subdivisions of these types identified small and standard swarms within the type 1 group and large and superswarms within the type 2 group. A minor group (swarm type 3) was also found, containing swarms that were isolated (>100 km away from the next swarm). The distribution of swarm types over the survey grid was examined with respect to a number of potential explanatory variables describing both the environment and the internal-state of krill (namely maturity, body length, body condition). Most variables were spatially averaged over scales of similar to 100 km and so mainly had a mesoscale perspective. The exception was the level of light (photosynthetically active radiation (PAR)) for which measurements were specific to each swarm. A binary logistic model was constructed from four variables found to have significant explanatory power (P < 0.05): surface fluorescence, PAR, krill maturity and krill body length. Larger (type 2) swarms were more commonly found during nighttime or when it was overcast during the day, when surface fluorescence was low, and when the krill were small and immature. A ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Euphausia superba Scotia Sea Natural Environment Research Council: NERC Open Research Archive Antarctic Scotia Sea Deep Sea Research Part I: Oceanographic Research Papers 56 11 1994 2012 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Marine Sciences Zoology Ecology and Environment |
spellingShingle |
Marine Sciences Zoology Ecology and Environment Tarling, Geraint A. Klevjer, Thor Fielding, Sophie Watkins, Jon Atkinson, Angus Murphy, Eugene Korb, Rebecca Whitehouse, Mick Leaper, Russell Variability and predictability of Antarctic krill swarm structure |
topic_facet |
Marine Sciences Zoology Ecology and Environment |
description |
Swarming is a fundamental part of the life of Euphausia superba, yet we still know very little about what drives the considerable variability in swarm shape, size and biomass. We examined swarms across the Scotia Sea in January and February 2003 using a Simrad EK60 (38 and 120 kHz) echosounder, concurrent with net sampling. The acoustic data were analysed through applying a swarm-identification algorithm and then filtering out all non-krill targets. The area, length, height, depth, packing-concentration and inter-swarm distance of 4525 swarms was derived by this method. Hierarchical clustering revealed 2 principal swarm types, which differed in both their dimensions and packing-concentrations. Type 1 swarms were generally small (<50 m long) and were not very tightly packed (<10 in.m(-3)), whereas type 2 swarms were an order of magnitude larger and had packing concentrations up to 10 times greater. Further subdivisions of these types identified small and standard swarms within the type 1 group and large and superswarms within the type 2 group. A minor group (swarm type 3) was also found, containing swarms that were isolated (>100 km away from the next swarm). The distribution of swarm types over the survey grid was examined with respect to a number of potential explanatory variables describing both the environment and the internal-state of krill (namely maturity, body length, body condition). Most variables were spatially averaged over scales of similar to 100 km and so mainly had a mesoscale perspective. The exception was the level of light (photosynthetically active radiation (PAR)) for which measurements were specific to each swarm. A binary logistic model was constructed from four variables found to have significant explanatory power (P < 0.05): surface fluorescence, PAR, krill maturity and krill body length. Larger (type 2) swarms were more commonly found during nighttime or when it was overcast during the day, when surface fluorescence was low, and when the krill were small and immature. A ... |
format |
Article in Journal/Newspaper |
author |
Tarling, Geraint A. Klevjer, Thor Fielding, Sophie Watkins, Jon Atkinson, Angus Murphy, Eugene Korb, Rebecca Whitehouse, Mick Leaper, Russell |
author_facet |
Tarling, Geraint A. Klevjer, Thor Fielding, Sophie Watkins, Jon Atkinson, Angus Murphy, Eugene Korb, Rebecca Whitehouse, Mick Leaper, Russell |
author_sort |
Tarling, Geraint A. |
title |
Variability and predictability of Antarctic krill swarm structure |
title_short |
Variability and predictability of Antarctic krill swarm structure |
title_full |
Variability and predictability of Antarctic krill swarm structure |
title_fullStr |
Variability and predictability of Antarctic krill swarm structure |
title_full_unstemmed |
Variability and predictability of Antarctic krill swarm structure |
title_sort |
variability and predictability of antarctic krill swarm structure |
publisher |
Elsevier |
publishDate |
2009 |
url |
http://nora.nerc.ac.uk/id/eprint/11310/ http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VGB-4WTRS81-1-R&_cdi=6034&_user=1773399&_orig=browse&_coverDate=11%2F30%2F2009&_sk=999439988&view=c&wchp=dGLbVzz-zSkWb&md5=c40f22bae01a938bb6bfbc18df328fcc&ie=/sdarticle.pdf |
geographic |
Antarctic Scotia Sea |
geographic_facet |
Antarctic Scotia Sea |
genre |
Antarc* Antarctic Antarctic Krill Euphausia superba Scotia Sea |
genre_facet |
Antarc* Antarctic Antarctic Krill Euphausia superba Scotia Sea |
op_relation |
Tarling, Geraint A. orcid:0000-0002-3753-5899 Klevjer, Thor; Fielding, Sophie orcid:0000-0002-3152-4742 Watkins, Jon; Atkinson, Angus; Murphy, Eugene orcid:0000-0002-7369-9196 Korb, Rebecca; Whitehouse, Mick; Leaper, Russell. 2009 Variability and predictability of Antarctic krill swarm structure. Deep-Sea Research Part I, 56 (11). 1994-2012. https://doi.org/10.1016/j.dsr.2009.07.004 <https://doi.org/10.1016/j.dsr.2009.07.004> |
op_doi |
https://doi.org/10.1016/j.dsr.2009.07.004 |
container_title |
Deep Sea Research Part I: Oceanographic Research Papers |
container_volume |
56 |
container_issue |
11 |
container_start_page |
1994 |
op_container_end_page |
2012 |
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1766214481848827904 |