Modulation of the free amino acid pool and protein content in populations of the brine shrimp Artemia spp.

Free amino acid (FAA) and protein content were measured in various developm ental stages of Artemia franciscana, from cysts to Instar III metanauplii. In addition, decapsulated cysts of 15 Artemia populations from different lo calities were compared with respect to their FAA and protein content. Furth ermore, the content and composition of the FAA pool were modulated by hatch ing the cysts at various salinities, and by enriching the nauplii with alga e or a lipid-enrichment emulsion. The FAA content increased threefold from cysts to nauplii, and Instar III metanauplii contained nearly 50% taurine o f total FAA. Cysts of A. franciscana were found to contain one-third the am ount of FAA compared to the other Artemia species investigated. The content and pool composition of FAA was successfully modulated in 11 of 13 populat ions! where by the content of FAA was significantly increased when hatched at high salinity. Finally, enrichment elevated the content of FAA and chang ed the pool composition, thereby showing a dietary effect. Algal enrichment also increased the protein content.