EGG AND DIETARY FATTY ACID CONCENTRATIONS AFFECT N-3 FATTY ACID METABOLISM IN LARVAE OF RED DRUM Sciaenops ocellatus

 Mounting evidence has shown that variations in egg and dietary lipid composition can differentially affect lipid metabolism in marine fish larvae. Previous work on red drum (Sciaenops ocellatus ) has shown that the docosahexaenoic acid (DHA) content of the egg is positively correlated with fatty acid composition of whole larvae weeks after hatching when larvae are fed a diet containing sufficient DHA. The current study examined the influence of endogenous (maternally derived) and exogenous nutrition of red drum larvae on subsequent  whole-body  accumulation of n-3 highly unsaturated fatty acids (HUFAs).

Two groups of red drum broodstock were fed different diets to produce eggs containing high or low levels of DHA. Larvae from these groups were fed live prey that were enriched to provide  high levels of  DHA  or low levels of DHA with high levels of α -linolenic acid (ALA).  These larval diets were presented during the rotifer-feeding stage and during the  Artemia feeding stage. Larvae were sampled at 7, 10, 17, and 21 days post-hatching (dph) to assess n-3 HUFA content.

W hen levels of DHA  in the larval diet were low, larvae from eggs containing l ow levels of DHA  had  higher levels of  ALA and some other fatty acids in the n-3 biosynthetic pathway than larvae from eggs containing high levels of DHA.  In addition, larvae that were fed low levels of DHA in rotifers  (fed 3 to 12 dph)  had  higher  tissue  levels of docosapentaenoic acid at 10, 17, and 21 dph, irrespective of egg DHA content.

These results suggest that  embryonic  early larval DHA restriction upregulates the n-3 biosynthesis pathway,  resulting in a stronger compensatory response (n-3 biosynthesis) to a  subsequent dietary challenge (low intake of DHA) compared to embryos that receive higher amounts of DHA.