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Biol Lett. Oct 23, 2010; 6(5): 682–684.
Published online Mar 17, 2010. doi:  10.1098/rsbl.2010.0082
PMCID: PMC2936134
The feeding ecology of little auks raises questions about winter zooplankton stocks in North Atlantic surface waters
Jérôme Fort,1* Yves Cherel,2 Ann M. A. Harding,3 Carsten Egevang,4 Harald Steen,5 Grégoire Kuntz,1 Warren P. Porter,6 and David Grémillet1,7
1Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 du CNRS, 1919 Route de Mende, 34293 Montpellier cedex 5, France
2Centre d'Etudes Biologiques de Chizé, UPR 1934 du CNRS, 79360 Villiers-en-Bois, France
3Environmental Science Department, Alaska Pacific University, 4101 University Drive, Anchorage, AK 99508, USA
4Greenland Institute of Natural Resources, PO Box 570, Kivioq 2, 3900 Nuuk, Greenland
5Norwegian Polar Institute, Polar Environmental Centre, 9296 Tromsø, Norway
6Department of Zoology, University of Wisconsin, 250 N. Mills Street, Madison, WI 53706, USA
7Percy FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa
*Author for correspondence (fort.jerome/at/gmail.com).
Received January 26, 2010; Accepted February 22, 2010.
Abstract
Copepods are essential components of marine food webs worldwide. In the North Atlantic, they are thought to perform vertical migration and to remain at depths more than 500 m during winter. We challenge this concept through a study of the winter feeding ecology of little auks (Alle alle), a highly abundant planktivorous seabird from the North Atlantic. By combining stable isotope and behavioural analyses, we strongly suggest that swarms of copepods are still available to their predators in water surface layers (less than 50 m) during winter, even during short daylight periods. Using a new bioenergetic model, we estimate that the huge number (20–40 million birds) of little auks wintering off southwest Greenland consume 3600–7200 tonnes of copepods daily, strongly suggesting substantial zooplankton stocks in surface waters of the North Atlantic in the middle of the boreal winter.
Keywords: diving behaviour, energetic modelling, food requirements, marine food web, stable isotope, seabird
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