Lipid composition of the pelagic tunicate Dolioletta gegenbauri (Tunicata, Thaliacea)

The free-swimming sexual stage (gonozoid) of the doliolid, Dolioletta gegenbauri , was abundant at a site in the NE Atlantic (58°W, 20°N) during June 1996. Lipid analysis indicated that these organisms were comprised mainly of polar lipid with only low levels of neutral storage lipid (triacylglycerols) and this is consistent with a life history strategy of rapid somatic growth and gamete production. Fatty acid analysis of the gonozoids suggested a diverse microplanktonic diet, comprising diatoms, flagellates and dinoflagellates. The fatty acid composition of D.gegenbauri was dominated by 20:5(n−3) and 22:6(n−3), and is of high nutritional value to predators, particularly fish. The results are discussed in relation to the organisms' life history strategy and their potential nutritional impact on higher trophic levels.