Journal of Lipid Research, Vol 27, 274-285, Copyright © 1986 by Lipid Research, Inc.
Lipids of North Atlantic krill
O Saether, TE Ellingsen and V Mohr
The seasonal variations in the total lipid content, lipid class
composition, fatty acid composition, and fatty alcohol composition of
Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Kroyer), and T.
raschii (M. Sars) have been examined. The total lipid content was highest
in the autumn and early winter months and lowest in the spring. In M.
norvegica, triacylglycerols served as the only depot lipids, whereas in T.
inermis and T. raschii triacylglycerols, wax esters, and
glycerophospholipids varied in proportion to the total lipid content. This
suggests that glycerophospholipids, as well as wax esters and
triacylglycerols, constitute depot lipids in these species. Wax esters and
glycerophospholipids were the dominating depot lipids in T. inermis,
whereas triacylglycerols and glycerophospholipids were most important in T.
raschii. Results suggest that non-depot glycerophospholipids may constitute
3.5-4.5% of the dry weight of the three species of krill examined. T.
inermis and T. raschii, from the same catches, had very similar fatty acid
compositions for each of the major lipid classes, with the exception of a
few minor fatty acids. The major lipid classes in all three species showed
complex seasonal variations in the content of the fatty acids that
typically reflect the diet, particularly in the case of the
triacylglycerols. The results suggest that all the species examined are
more herbivorous during the summer than during the autumn and winter. M.
norvegica seemed to be significantly more carnivorous than the two
Thysanoessa species. The degree of incorporation of individual fatty acids
from the diet is probably specific for each lipid class in each krill
species. The proportion of polyenoic fatty acids in the
glycerophospholipids and the proportion of monoenoic fatty acids in the wax
esters may be of importance for the temperature adaptation of T. inermis
and T. raschii.
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