ORIGINAL PAPER Life strategy and diet of Calanus glacialis during the winter–spring transition in Amundsen Gulf, south-eastern Beaufort Sea Anette Wold • Ge ´rald Darnis • Janne E. Søreide • Eva Leu • Benoit Philippe • Louis Fortier • Michel Poulin • Gerhard Kattner • Martin Graeve • Stig Falk-Petersen Received: 30 September 2010 / Revised: 27 June 2011 / Accepted: 27 June 2011 / Published online: 2 August 2011 Ó Springer-Verlag 2011 Abstract The copepod Calanus glacialis plays a key role in the lipid-based energy flux in Arctic shelf seas. By uti- lizing both ice algae and phytoplankton, this species is able to extend its growth season considerably in these season- ally ice-covered seas. This study investigated the impacts of the variability in timing and extent of the ice algal bloom on the reproduction and population success of C. glacialis. The vertical distribution, reproduction, amount of storage lipids, stable isotopes, fatty acid and fatty alcohol compo- sition of C. glacialis were assessed during the Circumpolar Flaw Lead System Study. Data were collected in the Amundsen Gulf, south-eastern Beaufort Sea, from January to July 2008 with the core-sampling from March to April. The reduction in sea ice thickness and coverage observed in the Amundsen Gulf in 2007 and 2008 affected the life strategy and reproduction of C. glacialis. Developmental stages CIII and CIV dominated the overwintering popula- tion, which resulted in the presence of very few CV and females during spring 2008. Spawning began at the peak of the ice algal bloom that preceded the precocious May ice break-up. Although the main recruitment may have occurred later in the season, low abundance of females combined with a potential mismatch between egg produc- tion/development to the first feeding stage and phyto- plankton bloom resulted in low recruitment of C. glacialis in the early summer of 2008. Keywords Calanus glacialis  Life cycle  Reproduction  Ice algae  Fatty acid composition  Amundsen Gulf Introduction Calanus glacialis Jaschnov is an Arctic shelf copepod species with circumpolar distribution. It is abundant in the northern Barents Sea, along the east and west Greenland shelf, the Baffin Bay, through the Canadian Archipelago, along the north-west coast of North America, and the Siberian shelf and the White Sea (Jaschnov 1970; Hirche and Kwasniewski 1997). C. glacialis together with C. hyperboreus Krøyer make up [ 70% of the zooplankton biomass in the south-eastern Beaufort Sea (Darnis et al. This article belongs to the special issue ‘‘Circumpolar Flaw Lead Study (CFL)’’, coordinated by J. Deming and L. Fortier. A. Wold (&)  E. Leu  S. Falk-Petersen Norwegian Polar Institute, 9296 Tromsø, Norway e-mail: anette.wold@npolar.no G. Darnis  L. Fortier Canada Research Chair on the response of Arctic marine ecosystems to climate change, Que ´bec-Oce ´an, De ´partement de biologie, Universite ´ Laval, 1045 avenue de la Me ´decine, Que ´bec, QC G1V 0A6, Canada J. E. Søreide University Centre in Svalbard, PB 156, 9171 Longyearbyen, Norway B. Philippe Institut des sciences de la mer, Universite ´ du Que ´bec a ` Rimouski, Rimouski, QC G5L 3Al, Canada M. Poulin Research Division, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, ON K1P 6P4, Canada G. Kattner  M. Graeve Alfred-Wegener-Institut fu ¨r Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany S. Falk-Petersen Department of Arctic and Marine Biology-BFE, University of Tromsø, 9037 Tromsø, Norway 123 Polar Biol (2011) 34:1929–1946 DOI 10.1007/s00300-011-1062-6