Energy vs. essential fatty acids: what do scallop larvae (Argopecten purpuratus) need most?
Larvae of the Chilean-Peruvian scallop Argopecten purpuratus were fed a Dunaliella tertiolecta diet (Dun-diet) supplemented with lipid emulsions, rich in 20:5n-3 (EmEPA), 22:6n-3 (EmDHA) or in saturated fatty acids (EmCOCO). A mixed algal diet of Isochrysis galbana (T-iso) and Chaetoceros neogracile served as a positive control (St-diet). Lipid supplementation to the Dun-diet improved the larval growth and increased the percentage of eyed larvae significantly, compared to the non-supplemented Dun-diet because of the extra energy supplied and not because of its fatty acid composition. No significant differences were observed between supplementation with EmEPA, EmDHA or EmCOCO. A mixture of 20% EmEPA+20% EmDHA (40% EmHUFA) was more efficient in raising the total lipid content in larvae than 40% EmCOCO. Both emulsions increased the triacylglycerol content in larvae compared to the non-supplemented Dun-diet. The best result, however, was obtained with the St-diet, probably because of a more suitable 18:2n-6/18:3n-3 ratio and a higher level of arachidonic acid. A positive relationship between the 18:2n-6/18:3n-3 ratio and the larval performance was found. No significant difference was observed in post-settlement larval size or percentage of metamorphosed larvae between the St-diet and the St-diet supplemented with 20% EmHUFA or 20% EmCOCO. The metamorphosed larvae had a constant DHA/EPA ratio of 3.7, independent from the diet, which suggested a metabolic control of the two fatty acids and a species-dependency of the ratio.
Nevejan
Nancy
N
Universidad de Los Lagos, Laboratory of Genetics and Aquaculture, P.O. Box 933, Osorno, Chile. Nancy.Nevejan@rug.ac.be
Saez
Iris
I
Gajardo
Gonzalo
G
Sorgeloos
Patrick
P
D000818:Animals; D004032:Diet; D004734:Energy Metabolism; D005228:Fatty Acids, Essential / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development*; D008055:Lipids / Q000032:analysis / Q000494:pharmacology; D008675:Metamorphosis, Biological / Q000187:drug effects; D008974:Mollusca; D009747:Nutritional Physiological Phenomena; D014280:Triglycerides / Q000032:analysis
D005228:Fatty Acids, Essential; D008055:Lipids; D014280:Triglycerides