Lipid Composition of Some Typical North Sea Copepods

Abstract

Copepods of the southern North Sea and Wadden Sea were investigated with special respect to the main lipid groups as well as to their fatty-acid pattern. The seasonal variation of lipids of the small copepods Temora longicornjs, Acartia clausi and Centropages hamatus was determined; in addition some zooplankters, which could only be sampled sporadically, were analysed. The seasonal values for total lipids from the small copepods varied between 0,3 and 1 pg ind.-', with maximal concentrations during spring and autumn. In addition to fatty-acid pattern, the proportions of triglycerides, phospholipids and free fatty acids were determined. The triglycerides are fixed as depot lipid with high seasonal variation in their concentrations (the main lipid component). Phospholipids exhibited less variation, which is to be expected, since they are incorporated as structural lipids in membranes. A comparison of the feeding behav~orb etween omnivorous copepods and copepods characterized by selective feeding shows that the fatty-acid pattern seems to depend on the type of food ingested. In selective feeders the proportion of polyunsaturated fatty acids is greater than in omnivorous copepods.