The fate of dietary lipids in the Arctic ctenophore Mertensia ovum (Fabricius 1780)
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Lipids of the Arctic ctenophore Mertensia ovum, collected from Kongsfjorden (Svalbard) in 2001, were analysed to investigate seasonal variability and fate of dietary lipids. Total lipids, lipid classes and fatty acid and alcohol compositions were determined in animals, which were selected according to age-group and season. Changes in lipids of age-group 0 animals were followed during growth from spring to autumn. Total lipids increased from May to September. Lipids as percentage of dry mass were lowest in August indicating their use for reproduction. Higher values occurred in September, which may be due to lipid storage for overwintering. Wax esters were the major lipid class accounting for about 50% of total lipids in age-group 0 animals from July and August. Phospholipids were the second largest lipid fraction with up to 46% in this age-group. The principal fatty acids of M. ovum from all age-groups were 22:6(n-3), 20:5(n-3) and 16:0. Wax ester fatty alcohols were dominated by 22:1(n-11) and 20:1(n-9) followed by moderate proportions of 16:0. The unique feature of M. ovum lipids was the high amount of free fatty alcohols originating probably from the dietary wax esters. In May, free alcohols exhibited the highest mean proportion with 14.6% in age-group 0 animals. We present the first data describing a detailed free fatty alcohol composition in zooplankton. This composition was very different from the alcohol composition of M. ovum wax esters because of the predominance of the long-chain monounsaturated 22:1(n-11) alcohol accounting for almost 100% of total free alcohols in some samples. The detailed lipid composition clearly reflected feeding of M. ovum on the herbivorous calanoid species, Calanus glacialis and C. finmarchicus, the abundant members of the zooplankton community in Kongsfjorden. Other copepod species or prey items seem to be less important for M. ovum.
KeywordsLipid Class Fatty Alcohol High Performance Thin Layer Chromatography Free Alcohol Major Lipid Class
We are grateful to the captain and crew of “Oceania”, RV Haakon Mosby and “Lance” and the staff of Kings Bay AS in Ny-Ålesund for their professional support during field experiments. We would like to thank Charlotte Gannefors, Anette Wold and Marthi Wolff for their important assistance. This work was supported by the Personnel Exchange Programme between the Research Council of Norway and Deutscher Akademischer Austauschdienst (DAAD).
- Folch J, Lees M, Stanley GHS (1957) A simple method for the isolation and purification of total lipides from animal tissues. J Biol Chem 226:497–509Google Scholar
- Graeve M (1992) Umsatz und Verteilung von Lipiden in arktischen marinen Organismen unter besonderer Berücksichtigung unterer trophischer Stufen. Ber Polarforsch 124:1–140Google Scholar
- Granhag L, Norrbin F, Haanes H, Henriksen J, Kolb J (2005) Feeding preference of the Arctic ctenophore Mertensia ovum. ASLO Aquatic Sciences Meeting, Santiago de Compostella, SpainGoogle Scholar
- Hop H, Pearson T, Hegseth EN, Kovacs KM, Wiencke C, Kwasniewski S, Eiane K, Mehlum F, Gulliksen B, Wlodarska-Kowalczuk M, Lydersen C, Weslawski JM, Cochrane S, Gabrielsen GW, Leakey RJG, Lønne OJ, Zajaczkowski M, Falk-Petersen S, Kendall M, Wängberg S-Å, Bischof K, Voronkov AY, Kovaltchouk NA, Wiktor J, Poltermann M, di Prisco G, Papucci C, Gerland S (2002) The marine ecosystem of Kongsfjorden, Svalbard. Polar Res 21:167–208CrossRefGoogle Scholar
- Phleger CF, Nichols PD, Virtue P (1998) Lipids and trophodynamics of Antarctic zooplankton. Comp Biol Physiol 120B:311–323Google Scholar
- Sargent JR, Henderson RJ (1986) Lipids. In: Corner EDS, O’ Hara E (eds) Biological chemistry of marine copepods. University Press, Oxford, pp 59–108Google Scholar
- Scott CL, Kwasniewski S, Falk-Petersen S, Sargent JR (2002) Species differences, origins and functions of fatty alcohols and fatty acids in the wax esters and phospholipids of Calanus hyperboreus, C. glacialis and C. finmarchicus from Arctic waters. Mar Ecol Prog Ser 235:127–134CrossRefGoogle Scholar
- Walkusz W, Storemark K, Skau T, Gannefors C, Lundberg M (2003) Zooplankton community structure; a comparison of fjords, open water and ice stations in the Svalbard area. Pol Polar Res 24:149–165Google Scholar