THE COMPOSITIONS OF WAX ESTERS, TRIACYLGLYCEROLS AND PHOSPHOLIPIDS INARCTIC AND ANTARCTIC COPEPODS - EVIDENCE OF ENERGETIC ADAPTATIONS

The fatty acid and fatty alcohol compositions of wax esters, triacylgl ycerols and phospholipids were determined in the Antarctic copepods Ca lanoides acutus, Calanus propinquus, Metridia gerlachei, Euchaeta anta rctica and Euchirella rostromagna and in the Arctic copepods Calanus h yperboreus, C. glacialis, C. finmarchicus and M. longa to reveal simil arities and differences between the nine species. The wax esters of th e herbivorous species were clearly characterised by the long-chain mon ounsaturated fatty acids and alcohols 20:1 (n-9) and 22:1 (n-11), wher eas the omnivorous and carnivorous species usually had high relative a mounts of the 18:1 (n-9) fatty acid and of the short-chain saturated a lcohols 14:0 and 16:0. The wax eater-storing copepods contained only s mall amounts of triacylglycerol, but the latter was the dominant depot lipid in the Antarctic C. propinquus and E. rostomagna. The triacylgl ycerol fatty acid composition of C. propinquus deviated strongly from those of all other species due to large amounts of the two isomers 22: 1 (n-11) and 22:1 (n-9). The wax eater molecules of the herbivorous sp ecies had the highest energetic content, although the triacylglycerols of C. propinquus reached very similar energy levels. The wax ester-st oring herbivorous species have developed similar lipid biochemical ada ptations in both polar oceans. In contrast, predominantly triacylglyce rol-storing species occur only in Antarctic waters. The phospholipids contained very high levels of polyunsaturated fatty acids, especially 22:6 (n-3), which was about twice as abundant as 20:5 (n-3) and 16:0, the other characteristic fatty acids. In both, Arctic and Antarctic sp ecies, the fatty acid compositions of the phospholipids showed a prono unced uniformity. The extremely high degree of unsaturation is extraor dinary as compared to other marine taxa.