Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013
Antarctic krill ( Euphausia superba ) are a key species in Southern Ocean ecosystems, maintaining very large numbers of predators, and fluctuations in their abundance can affect the overall structure and functioning of the ecosystems. The interannual variability in the abundance and biomass of krill...
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fthighwire:oai:open-archive.highwire.org:icesjms:71/9/2578 2023-05-15T13:33:45+02:00 Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 Fielding, Sophie Watkins, Jonathan L. Trathan, Philip N. Enderlein, Peter Waluda, Claire M. Stowasser, Gabriele Tarling, Geraint A. Murphy, Eugene J. 2014-11-01 00:00:00.0 text/html http://icesjms.oxfordjournals.org/cgi/content/short/71/9/2578 https://doi.org/10.1093/icesjms/fsu104 en eng Oxford University Press http://icesjms.oxfordjournals.org/cgi/content/short/71/9/2578 http://dx.doi.org/10.1093/icesjms/fsu104 Copyright (C) 2014, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer Original Articles TEXT 2014 fthighwire https://doi.org/10.1093/icesjms/fsu104 2015-02-28T22:22:56Z Antarctic krill ( Euphausia superba ) are a key species in Southern Ocean ecosystems, maintaining very large numbers of predators, and fluctuations in their abundance can affect the overall structure and functioning of the ecosystems. The interannual variability in the abundance and biomass of krill was examined using a 17-year time-series of acoustic observations undertaken in the Western Core Box (WCB) survey area to the northwest of South Georgia, Southern Ocean. Krill targets were identified in acoustic data using a multifrequency identification window and converted to krill density using the Stochastic Distorted-Wave Born Approximation target strength model. Krill density ranged over several orders of magnitude (0–10 000 g m−2) and its distribution was highly skewed with many zero observations. Within each survey, the mean krill density was significantly correlated with the top 7% of the maximum krill densities observed. Hence, only the densest krill swarms detected in any one year drove the mean krill density estimates for the WCB in that year. WCB krill density ( µ , mean density for the area) showed several years (1997/1998, 2001–2003, 2005–2007) of high values ( µ > 30 g m−2) interspersed with years (1999/2000, 2004, 2009/2010) of low density ( µ < 30 g m−2). This pattern showed three different periods, with fluctuations every 4–5 years. Cross correlation analyses of variability in krill density with current and lagged indices of ocean (sea surface temperature, SST and El Niño /Southern Oscillation) and atmospheric variability (Southern Annular Mode) found the highest correlation between krill density and winter SST (August SST) from the preceding year. A quadratic regression ( r 2 = 0.42, p < 0.05) provides a potentially valuable index for forecasting change in this ecosystem. Text Antarc* Antarctic Antarctic Krill Euphausia superba Southern Ocean HighWire Press (Stanford University) Antarctic Southern Ocean ICES Journal of Marine Science 71 9 2578 2588 |
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HighWire Press (Stanford University) |
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English |
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Original Articles |
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Original Articles Fielding, Sophie Watkins, Jonathan L. Trathan, Philip N. Enderlein, Peter Waluda, Claire M. Stowasser, Gabriele Tarling, Geraint A. Murphy, Eugene J. Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
topic_facet |
Original Articles |
description |
Antarctic krill ( Euphausia superba ) are a key species in Southern Ocean ecosystems, maintaining very large numbers of predators, and fluctuations in their abundance can affect the overall structure and functioning of the ecosystems. The interannual variability in the abundance and biomass of krill was examined using a 17-year time-series of acoustic observations undertaken in the Western Core Box (WCB) survey area to the northwest of South Georgia, Southern Ocean. Krill targets were identified in acoustic data using a multifrequency identification window and converted to krill density using the Stochastic Distorted-Wave Born Approximation target strength model. Krill density ranged over several orders of magnitude (0–10 000 g m−2) and its distribution was highly skewed with many zero observations. Within each survey, the mean krill density was significantly correlated with the top 7% of the maximum krill densities observed. Hence, only the densest krill swarms detected in any one year drove the mean krill density estimates for the WCB in that year. WCB krill density ( µ , mean density for the area) showed several years (1997/1998, 2001–2003, 2005–2007) of high values ( µ > 30 g m−2) interspersed with years (1999/2000, 2004, 2009/2010) of low density ( µ < 30 g m−2). This pattern showed three different periods, with fluctuations every 4–5 years. Cross correlation analyses of variability in krill density with current and lagged indices of ocean (sea surface temperature, SST and El Niño /Southern Oscillation) and atmospheric variability (Southern Annular Mode) found the highest correlation between krill density and winter SST (August SST) from the preceding year. A quadratic regression ( r 2 = 0.42, p < 0.05) provides a potentially valuable index for forecasting change in this ecosystem. |
format |
Text |
author |
Fielding, Sophie Watkins, Jonathan L. Trathan, Philip N. Enderlein, Peter Waluda, Claire M. Stowasser, Gabriele Tarling, Geraint A. Murphy, Eugene J. |
author_facet |
Fielding, Sophie Watkins, Jonathan L. Trathan, Philip N. Enderlein, Peter Waluda, Claire M. Stowasser, Gabriele Tarling, Geraint A. Murphy, Eugene J. |
author_sort |
Fielding, Sophie |
title |
Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
title_short |
Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
title_full |
Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
title_fullStr |
Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
title_full_unstemmed |
Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997-2013 |
title_sort |
interannual variability in antarctic krill (euphausia superba) density at south georgia, southern ocean: 1997-2013 |
publisher |
Oxford University Press |
publishDate |
2014 |
url |
http://icesjms.oxfordjournals.org/cgi/content/short/71/9/2578 https://doi.org/10.1093/icesjms/fsu104 |
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_relation |
http://icesjms.oxfordjournals.org/cgi/content/short/71/9/2578 http://dx.doi.org/10.1093/icesjms/fsu104 |
op_rights |
Copyright (C) 2014, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer |
op_doi |
https://doi.org/10.1093/icesjms/fsu104 |
container_title |
ICES Journal of Marine Science |
container_volume |
71 |
container_issue |
9 |
container_start_page |
2578 |
op_container_end_page |
2588 |
_version_ |
1766045750963208192 |