We investigated the ability of four species of marine zooplankton to synthesize polyunsaturated
fatty acids (PUFAs) during pulse-chase tracer experiments. Liposomes containing a deuterium
labelled precursor fatty acid, D5-18:3n-3, were fed to female Calanus finmarchicus, Calanoides
acutus, Drepanopus forcipatus and calyptopus larvae of Euphausia superba during ship-board
experiments. Although all species of zooplankton readily ingested the liposomes and incorporated
the D5-18:3n-3 tracer into their somatic lipid pool, only negligible products of elongation and
desaturation; D5-18:4n-3, D5-20:5n-3 and D5-22:6n-3 were detected after 96 h incubations.
We conclude that the four species of marine zooplankton examined here are unable to synthesize
PUFA at ecologically significant rates and certainly not in amounts sufficient to support growth
and reproductive processes