Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem
Variability is a key feature of the pelagic ecosystems of the Southern Ocean and an important aspect of the variation is fluctuation in the abundance of krill Euphausia superba Dana, the major prey item of many of the higher predators. Direct impacts of variability in the large-scale physical enviro...
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ftnerc:oai:nora.nerc.ac.uk:20102 2023-05-15T16:08:29+02:00 Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem Murphy, Eugene J. Reid, Keith 2001 http://nora.nerc.ac.uk/id/eprint/20102/ http://www.int-res.com/articles/meps/217/m217p175.pdf unknown Inter-Research Murphy, Eugene J. orcid:0000-0002-7369-9196 Reid, Keith. 2001 Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem. Marine Ecology Progress Series, 217. 175-189. https://doi.org/10.3354/meps217175 <https://doi.org/10.3354/meps217175> Publication - Article PeerReviewed 2001 ftnerc https://doi.org/10.3354/meps217175 2023-02-04T19:32:39Z Variability is a key feature of the pelagic ecosystems of the Southern Ocean and an important aspect of the variation is fluctuation in the abundance of krill Euphausia superba Dana, the major prey item of many of the higher predators. Direct impacts of variability in the large-scale physical environment, such as changes in ocean circulation, have been suggested as the main factor generating the observed fluctuations. So far, however, there has been little quantitative assessment of the importance of krill population dynamics in the observed variation. Here, analyses of a model of krill population development and predator diet data from South Georgia have been used to examine seasonal changes in the population structure of krill. The krill population model was combined with a size-based selection function and used to generate expected length-frequency distributions in the predator diet through a summer season. Comparison of the model solutions with the predator diet data indicates that the model can reproduce the observed pattern of variation and emphasizes that adult population changes are a key aspect of the interannual fluctuations observed during some years. Low krill abundance was associated with reduced representation of the 3+ age group (3 to 4 yr old), whereas when krill were abundant the 3+ age class was the major age group present. The seasonal changes in the population structure in the predator diet involve a complex interaction of relative year class strength, timing of immigration, fluctuations in growth rates and dynamic predatorselective effects. Development of the model to examine the interactive effects of changing krill growth and mortality rates will be a valuable next step. The dominance of the changes in krill population age structure underlines the fact that to understand the variability of the South Georgia ecosystem we must identify the major factors generating variability in population dynamics throughout the Scotia Sea. Article in Journal/Newspaper Euphausia superba Scotia Sea Southern Ocean Natural Environment Research Council: NERC Open Research Archive Southern Ocean Scotia Sea Marine Ecology Progress Series 217 175 189 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
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unknown |
description |
Variability is a key feature of the pelagic ecosystems of the Southern Ocean and an important aspect of the variation is fluctuation in the abundance of krill Euphausia superba Dana, the major prey item of many of the higher predators. Direct impacts of variability in the large-scale physical environment, such as changes in ocean circulation, have been suggested as the main factor generating the observed fluctuations. So far, however, there has been little quantitative assessment of the importance of krill population dynamics in the observed variation. Here, analyses of a model of krill population development and predator diet data from South Georgia have been used to examine seasonal changes in the population structure of krill. The krill population model was combined with a size-based selection function and used to generate expected length-frequency distributions in the predator diet through a summer season. Comparison of the model solutions with the predator diet data indicates that the model can reproduce the observed pattern of variation and emphasizes that adult population changes are a key aspect of the interannual fluctuations observed during some years. Low krill abundance was associated with reduced representation of the 3+ age group (3 to 4 yr old), whereas when krill were abundant the 3+ age class was the major age group present. The seasonal changes in the population structure in the predator diet involve a complex interaction of relative year class strength, timing of immigration, fluctuations in growth rates and dynamic predatorselective effects. Development of the model to examine the interactive effects of changing krill growth and mortality rates will be a valuable next step. The dominance of the changes in krill population age structure underlines the fact that to understand the variability of the South Georgia ecosystem we must identify the major factors generating variability in population dynamics throughout the Scotia Sea. |
format |
Article in Journal/Newspaper |
author |
Murphy, Eugene J. Reid, Keith |
spellingShingle |
Murphy, Eugene J. Reid, Keith Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
author_facet |
Murphy, Eugene J. Reid, Keith |
author_sort |
Murphy, Eugene J. |
title |
Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
title_short |
Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
title_full |
Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
title_fullStr |
Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
title_full_unstemmed |
Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem |
title_sort |
modelling southern ocean krill population dynamics: biological processes generating fluctuations in the south georgia ecosystem |
publisher |
Inter-Research |
publishDate |
2001 |
url |
http://nora.nerc.ac.uk/id/eprint/20102/ http://www.int-res.com/articles/meps/217/m217p175.pdf |
geographic |
Southern Ocean Scotia Sea |
geographic_facet |
Southern Ocean Scotia Sea |
genre |
Euphausia superba Scotia Sea Southern Ocean |
genre_facet |
Euphausia superba Scotia Sea Southern Ocean |
op_relation |
Murphy, Eugene J. orcid:0000-0002-7369-9196 Reid, Keith. 2001 Modelling Southern Ocean krill population dynamics: biological processes generating fluctuations in the South Georgia ecosystem. Marine Ecology Progress Series, 217. 175-189. https://doi.org/10.3354/meps217175 <https://doi.org/10.3354/meps217175> |
op_doi |
https://doi.org/10.3354/meps217175 |
container_title |
Marine Ecology Progress Series |
container_volume |
217 |
container_start_page |
175 |
op_container_end_page |
189 |
_version_ |
1766404530408259584 |