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Paradigm lost, or is top-down forcing no longer significant in the Antarctic marine ecosystem?

Published online by Cambridge University Press:  13 July 2007

David Ainley*
Affiliation:
H.T. Harvey & Associates, 3150 Almaden Expressway, San Jose, CA 95118, USA
Grant Ballard
Affiliation:
PRBO Conservation Science, Bolinas CA 94924USA; and Ecology, Evolution, and Behaviour, School of Biological Sciences, University of Auckland, New Zealand
Steve Ackley
Affiliation:
Civil & Environmental Engineering, Clarkson University, Potsdam, NY 13699, USA
Louise K. Blight
Affiliation:
Aquatic Ecosystems Research Laboratory, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
Joseph T. Eastman
Affiliation:
Biomedical Sciences, Ohio University, Athens, OH 45701, USA
Steven D. Emslie
Affiliation:
Biology and Marine Biology, University of North Carolina, Wilmington, NC 28403, USA
Amélie Lescroël
Affiliation:
H.T. Harvey & Associates, 3150 Almaden Expressway, San Jose, CA 95118, USA
Silvia Olmastroni
Affiliation:
Dipartimento Scienze Ambientali, Università di Siena, Via Mattioli 4 53100 Siena, Italy
Susan E. Townsend
Affiliation:
709 56th Street, Oakland, CA 94609, USA
Cynthia T. Tynan
Affiliation:
PO Box 438, West Falmouth, MA 02574, USA
Peter Wilson
Affiliation:
17 Modena Crescent, Auckland, New Zealand
Eric Woehler
Affiliation:
School of Zoology, University of Tasmania, Sandy Bay, TAS 7000, Australia

Abstract

Investigations in recent years of the ecological structure and processes of the Southern Ocean have almost exclusively taken a bottom-up, forcing-by-physical-processes approach relating various species' population trends to climate change. Just 20 years ago, however, researchers focused on a broader set of hypotheses, in part formed around a paradigm positing interspecific interactions as central to structuring the ecosystem (forcing by biotic processes, top-down), and particularly on a “krill surplus” caused by the removal from the system of more than a million baleen whales. Since then, this latter idea has disappeared from favour with little debate. Moreover, it recently has been shown that concurrent with whaling there was a massive depletion of finfish in the Southern Ocean, a finding also ignored in deference to climate-related explanations of ecosystem change. We present two examples from the literature, one involving gelatinous organisms and the other involving penguins, in which climate has been used to explain species' population trends but which could better be explained by including species interactions in the modelling. We conclude by questioning the almost complete shift in paradigms that has occurred and discuss whether it is leading Southern Ocean marine ecological science in an instructive direction.

Information

Type
Opinion
Copyright
Copyright © Antarctic Science Ltd 2007

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