Antarctic Science


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

David Ainleya1 c1, Grant Ballarda2, Steve Ackleya3, Louise K. Blighta4, Joseph T. Eastmana5, Steven D. Emsliea6, Amélie Lescroëla1, Silvia Olmastronia7, Susan E. Townsenda8, Cynthia T. Tynana9, Peter Wilsona10 and Eric Woehlera11

a1 H.T. Harvey & Associates, 3150 Almaden Expressway, San Jose, CA 95118, USA

a2 PRBO Conservation Science, Bolinas CA 94924 USA; and Ecology, Evolution, and Behaviour, School of Biological Sciences, University of Auckland, New Zealand

a3 Civil & Environmental Engineering, Clarkson University, Potsdam, NY 13699, USA

a4 Aquatic Ecosystems Research Laboratory, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada

a5 Biomedical Sciences, Ohio University, Athens, OH 45701, USA

a6 Biology and Marine Biology, University of North Carolina, Wilmington, NC 28403, USA

a7 Dipartimento Scienze Ambientali, Università di Siena, Via Mattioli 4 53100 Siena, Italy

a8 709 56th Street, Oakland, CA 94609, USA

a9 PO Box 438, West Falmouth, MA 02574, USA

a10 17 Modena Crescent, Auckland, New Zealand

a11 School of Zoology, University of Tasmania, Sandy Bay, TAS 7000, Australia


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.

(Received May 03 2006)

(Accepted September 25 2006)

(Online publication July 13 2007)


“New opinions are always suspected, and usually opposed, without any other reason but because they are not already common.” John Locke (1690), “An Enquiry Concerning Human Understanding”