Effect of algal addition on stability of fatty acids and some water-soluble vitamins in juvenile Artemia franciscana

A minor stabilization effect was found for the content of total lipids, tot al fatty acids and docosahexaenoic acid (DHA) when Artemia franciscana was maintained at high concentrations of Isochrysis galbana for 72 h at 12 degr eesC, both in 3- and 4-day-old individuals. The eicosapentaenoic (EPA) leve l was only stabilized at higher algal concentrations in the 4-day-old A. fr anciscana. In the 3-day-old A. franciscana, the EPA content increased at al l algal concentrations during the first 24 h of post enrichment, presumably as an effect of DHA catabolism. Apparently, the 4-day-old A. franciscana m etabolized DHA, and other lipids, faster than the 3-day-old A. franciscana did. During the 72 h incubation with I. galbana, the content of ascorbic ac id (AA) in A. franciscana increased approximately to 1000-1200 mug g(-1) dr y weight (DW) at algal concentrations above 3 mg C L-1, close to AA content of the algae. The vitamin B-6 content in A. franciscana decreased from app roximately 20 to 4-11 mug g(-1) DW, with highest loss rates at the higher a lgal concentrations. The thiamin content of A. franciscana was independent of algal concentration and remained at 20-30 mug g(-1) DW. The nutritional effects of the algal incubation on the 3- and 4-day-old A. franciscana at a lgal concentrations which can be used during the cultivation of Atlantic-ha libut larvae (<2 mg C L-1) was insignificant, except for the small enrichme nt effect of AA already at 1 mg C L-1. Other beneficial effects of the alga e should not be ruled out, like possible effects on the microflora of A. fr anciscana even at algal concentrations less than 2 mg C L-1.