THE USE OF LIPID EMULSIONS AS CARRIERS FOR ESSENTIAL FATTY-ACIDS IN BIVALVES - A TEST-CASE WITH JUVENILE PLACOPECTEN-MAGELLANICUS

Although information on bivalve nutrition is still very scarce, severa l studies have demonstrated the importance of lipids, in particular tr iglycerides, as a source of energy and essential fatty acids in the ea rly life stages. Experimental diets used so far to study bivalve nutri tion either heavily pollute the water or are too complex to prepare in a hatchery. The potential use of lipid emulsions as off-the-shelf sup plements was evaluated through the analytical verification of the inge stion and incorporation of n-3 highly unsaturated fatty acids (HUFA) b y the juvenile sea scallop Placopecten magellanicus fed lipid emulsion s of different fatty acid composition as a supplement to Isochrysis sp . (clone T-Iso). The average lipid content in the scallops fed the lip id supplements was 20% higher compared with that in the control fed al gae only (3.29 +/- 0.16 versus 2.75% of dry weight, respectively). Cha nges in the fatty acid composition, in particular of n-3 HUFA, were de monstrated in total lipids, polar lipids, and triglycerides of juvenil e sea scallops supplemented with lipid emulsions on the basis of ethyl ester concentrates of n-3 HUFA and were dependent on the level and pr oportion of 20:5n-3 and 22:6n-3 present in the emulsion. The effective incorporation of essential fatty acids from lipid emulsions indicated that the supplementation of lipid emulsions to live algae may improve and standardize the dietary supply of lipids and fatty acids in hatch ery production of bivalves.