POLAR HERBIVOROUS COPEPODS - DIFFERENT PATHWAYS IN LIPID BIOSYNTHESIS

Herbivorous copepods, especially from polar regions, buffer the pronou nced seasonality of primary production through the accumulation of lar ge energy reserves that are deposited as neutral lipids, mainly wax es ters but also triacylglycerols. Principal components of these lipids a re the long-chain monounsaturated fatty acids and alcohols 20:1(n-9) a nd 22:1(n-11). Wax ester synthesis based on these compounds is most pr onounced in the Arctic copepod, Calanus hyperboreus, but it is also ch aracteristic of the other dominant herbivores, Calanus glacialis and C alanus finmarchicus, as well as for the Antarctic Calanoides acutus. R hincalanus gigas, another Antarctic species, also fits this scheme of wax ester synthesizers, although its wax esters consist of shorter-cha in fatty acids and alcohols. In contrast, the Antarctic Calanus propin quus synthesizes triacylglycerols dominated by the two monounsaturated fatty acid isomers 22:1(n-11) and 22:1(n-9). This further elongation of the fatty acids increases their calorific Value and may at least pa rtially compensate this species' apparent inability to produce wax est ers. Other dominant fatty acids in the lipids of these copepods origin ate from dietary input and may be used as trophic markers for herbivor ous feeding. (C) 1995 International Council for the Exploration of the Sea