ORIGINAL PAPER Lipid composition of the three co-existing Calanus species in the Arctic: impact of season, location and environment P. Mayzaud 1,2 • S. Falk-Petersen 3,4 • M. Noyon 1,2,6 • A. Wold 4,5 • M. Boutoute 1,2 Received: 23 October 2014 / Revised: 27 April 2015 / Accepted: 1 June 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Arctic species of Calanus are critical to energy transfer between higher and lower trophic levels and their relative abundance, and lipid content is influenced by the alternation of cold and warm years. All three species of Calanus were collected during different periods in Kongsfjorden (Svalbard, 79°N) and adjacent shelf during the abnormally warm year of 2006. Lipid composition and fatty acid structure of individual lipid classes were exam- ined in relation with population structure. Wax esters dominated the neutral lipid fraction. Phosphatidylcholine (PC) dominated the structural lipids followed by phos- phatidylethanolamine (PE). PC/PE ratios of 3–6 suggested an increase in PC proportions compared to earlier studies. Depending on the time scale, fatty acids of wax esters illustrated either trophic differences between fjord and offshore conditions for C. hyperboreus and C. finmarchicus or trophic differences related to seasonality for C. glacialis. Similarly, seasonality and trophic conditions controlled the changes in fatty acids of triglycerides, but de novo syn- thesis of long-chain monoenes suggested energy opti- mization to cope with immediate metabolic needs. Polar lipids fatty acid composition was species specific and on the long-term (comparison with data from the past decade) composition appears related to changes in trophic envi- ronment. Fatty acid composition of PC and PE indicated relative dominance of 20:5n-3 in PC and 22:6n-3 in PE for all three species. The combination of PE and PC acyl chain and phospholipid head group restructuring indicates an inter-annual variability and suggests that membrane lipids are the most likely candidate to evaluate adaptive changes in Arctic copepods to hydrothermal regime. Keywords Arctic Á Calanus Á Lipids Á Fatty acids Á Polar lipids Á Climate Introduction Arctic marine ecosystems are experiencing substantial modifications related to climate change, which impact directly the physical (e.g., sea ice coverage and hydrology) and biological processes (Falk-Petersen et al. 2007). The two most critical aspects of the Arctic ecosystem func- tioning are the timing of the spring bloom (ice algae and phytoplankton) and the lipid-driven energy flows which control both the population structure and the energy transfer through the food web (Søreide et al. 2010). One of This article belongs to the special issue on the ‘‘Kongsfjorden ecosystem—new views after more than a decade of research’’, coordinated by Christian Wiencke and Haakon Hop. Electronic supplementary material The online version of this article (doi:10.1007/s00300-015-1725-9) contains supplementary material, which is available to authorized users. & P. Mayzaud mayzaud@obs-vlfr.fr 1 Laboratoire d’Oce ´anographie de Villefranche, UMR 7093, UPMC Universite ´ Paris 06, BP 28, 06234 Villefranche-Sur-Mer, France 2 CNRS, UMR 7093, LOV, BP 28, 06234 Villefranche-Sur-Mer, France 3 Akvaplan-niva, Fram Centre, 9296 Tromsø, Norway 4 Faculty of Biosciences, Fisheries and Economics, University of Tromsø, 9037 Tromsø, Norway 5 Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway 6 Department of Biological Sciences, Marine Research Institute, University of Cape Town, Rondebosch, Private Bag X3, 7701 Cape Town, South Africa 123 Polar Biol DOI 10.1007/s00300-015-1725-9