Ecological importance of the Southern Boundary of the Antarctic Circumpolar Current - Nature
- ️Tynan, Cynthia T.
- ️Thu Apr 16 1998
- Letter
- Published: 16 April 1998
Nature volume 392, pages 708–710 (1998)Cite this article
Abstract
The Southern Ocean surrounds the Antarctic continent and supports one of the most productive marine ecosystems. Migratory and endemic species of whales, seals and birds benefit from the high biomass of their principal prey, krill (Euphausia superba) and cephalopods, in this area. Most species of baleen whales and male sperm whales in the Southern Hemisphere migrate between low-latitude breeding grounds in winter and highly productive Antarctic feeding grounds in summer. Here I show the importance of the southernmost reaches of the strongest ocean current, the Antarctic Circumpolar Current (ACC), to a complex and predictable food web of the Southern Ocean. The circumpolar distributions of blue, fin and humpback whales from spring to midsummer trace the non-uniform high-latitude penetration of shoaled, nutrient-rich Upper Circumpolar Deep Water, which is carried eastward by the ACC. The poleward extent of this water mass delineates the Southern Boundary1 of the ACC and corresponds not only to the circumpolar distributions of baleen whales, but also to distributions of krill and to regions of high, seasonally averaged, phytoplankton biomass. Sperm whales, which feed on cephalopods2, also congregate in highest densities near the Southern Boundary. The association of primary production, Krill, and whales with the Southern Boundary, suggests that it provides predictably productive foraging for many species, and is of critical importance to the function of the Southern Ocean ecosystem.
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Acknowledgements
I thank D. P. DeMaster, R. L. Gentry, G. L. Kooyman, D. G. M. Miller, A. H. Orsi and J. Priddle for review of the manuscript, and A. H. Orsi for discussions and for providing the coordinates of the Southern Boundary of the ACC.
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Research Associate of the National Research Council, National Marine Mammal Laboratory, NOAA, 7600 Sand Point Way NE, Seattle, 98115, Washington, USA
Cynthia T. Tynan
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Tynan, C. Ecological importance of the Southern Boundary of the Antarctic Circumpolar Current. Nature 392, 708–710 (1998). https://doi.org/10.1038/33675
Received: 15 October 1996
Accepted: 15 January 1998
Issue Date: 16 April 1998
DOI: https://doi.org/10.1038/33675