Document Detail

Long-term decline in krill stock and increase in salps within the Southern Ocean.
MedLine Citation:
PMID:  15525989     Owner:  NLM     Status:  MEDLINE    
Antarctic krill (Euphausia superba) and salps (mainly Salpa thompsoni) are major grazers in the Southern Ocean, and krill support commercial fisheries. Their density distributions have been described in the period 1926-51, while recent localized studies suggest short-term changes. To examine spatial and temporal changes over larger scales, we have combined all available scientific net sampling data from 1926 to 2003. This database shows that the productive southwest Atlantic sector contains >50% of Southern Ocean krill stocks, but here their density has declined since the 1970s. Spatially, within their habitat, summer krill density correlates positively with chlorophyll concentrations. Temporally, within the southwest Atlantic, summer krill densities correlate positively with sea-ice extent the previous winter. Summer food and the extent of winter sea ice are thus key factors in the high krill densities observed in the southwest Atlantic Ocean. Krill need the summer phytoplankton blooms of this sector, where winters of extensive sea ice mean plentiful winter food from ice algae, promoting larval recruitment and replenishing the stock. Salps, by contrast, occupy the extensive lower-productivity regions of the Southern Ocean and tolerate warmer water than krill. As krill densities decreased last century, salps appear to have increased in the southern part of their range. These changes have had profound effects within the Southern Ocean food web.
Angus Atkinson; Volker Siegel; Evgeny Pakhomov; Peter Rothery
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Nature     Volume:  432     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-11-04     Completed Date:  2004-12-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  100-3     Citation Subset:  IM    
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 OET, UK. aat@
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MeSH Terms
Algae / physiology
Antarctic Regions
Chlorophyll / analysis
Databases, Factual
Euphausiacea / physiology*
Food Chain*
Ice Cover / microbiology
Oceans and Seas
Population Density
Seawater / analysis,  parasitology*
Time Factors
Reg. No./Substance:
1406-65-1/Chlorophyll; 479-61-8/chlorophyll a

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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