Oceanic circumpolar habitats of Antarctic krill

A. Atkinson*, V. Siegel, E. A. Pakhomov, P. Rothery, V. Loeb, R. M. Ross, L. B. Quetin, K. Schmidt, P. Fretwell, E. J. Murphy, G. A. Tarling, A. H. Fleming

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Surveys of Euphausia superba often target localised shelves and ice edges where their growth rates and predation losses are atypically high. Emphasis on these areas has led to the current view that krill require high food concentrations, with a distribution often linked to shelves. For a wider, circumpolar perspective, we compiled all available net-based density data on postlarvae from 8137 mainly summer stations from 1926 to 2004. Unlike Antarctic zooplankton, the distribution of E. superba is highly uneven, with 70 % of the total stock concentrated between longitudes 0° and 90° W. Within this Atlantic sector, krill are abundant over both continental shelf and ocean. At the Antarctic Peninsula they are found mainly over the inner shelf, whereas in the Indian-Pacific sectors krill prevail in the ocean within 200 to 300 km of the shelf break. Overall, 87% of the total stock lives over deep oceanic water (>2000 m), and krill occupy regions with moderate food concentrations (0.5 to 1.0 mg chl am-3). Advection models suggest some northwards loss from these regions and into the low chlorophyll belts of the Antarctic Circumpolar Current (ACC). We found possible evidence for a compensating southwards migration, with an increasing proportion of krill found south of the ACC as the season progresses. The retention of krill in moderately productive oceanic habitats is a key factor in their high total production. While growth rates are lower than over shelves, the ocean provides a refuge from shelf-based predators. The unusual circumpolar distribution of krill thus reflects a balance between advection, migration, top-down and bottom-up processes.

Original languageEnglish
Pages (from-to)1-23
Number of pages23
JournalMarine Ecology Progress Series
Volume362
DOIs
Publication statusPublished - 30 Jun 2008
Externally publishedYes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

Keywords

  • Bottom-up control
  • Circumpolar
  • Distribution
  • Euphausiid
  • Growth
  • Mortality
  • Predation
  • Risk
  • Top-down control

Fingerprint

Dive into the research topics of 'Oceanic circumpolar habitats of Antarctic krill'. Together they form a unique fingerprint.

Cite this