ASTM Practice for Using Brine Shrimp Nauplii as Food for Test Animals in Aquatic Toxicology Tests (E 1203) suggests use of Reference Artemia as a reference standard for evaluating other batches of brine shrimp as food for organisms used in toxicology. In 1988, the U.S. EPA was able to procure a 200-kg quantity of presumed high-quality, small-sized Artemia cysts that had been homogeneously mixed and packaged for long-term storage. These cysts and hatched nauplii have now been characterized in terms of fatty acid profile, toxicant residues, biometrics, and ability to support good survival and growth of saltwater fish and survival and reproduction of saltwater mysids. These cysts have been approved for use as reference cysts and have been designated RAC III.
The fatty acid profile of the RAC III includes a 20:5w3 level greater than 7%, which is in excess of the 5% minimum level recommended for marine fish and crustacean larvae. The size of the newly hatched nauplii is <430 μm, which is in the low end of the normal size range (420 to 520 μm) for Artemia nauplii from various strains. Thus they should be relatively easily ingested by marine fish larvae. Analyses of RAC III for metals, organophosphorus pesticides, chlorinated pesticides, and PCBs indicate no problems with toxicant residues.
RAC III nauplii were evaluated as a food for marine fish and crustaceans in comparison to RAC II nauplii and a known poor-quality Artemia. There were no statistical differences in survival and growth of sheepshead minnows (Cyprinodon variegatus) and inland silversides (Menidia beryllina) raised on RAC II and RAC III. Survival and reproduction of mysids (Mysidopsis bahia) raised for 25 days on RAC III were comparable to RAC II-raised mysids.
The availability of RAC III to U.S. marine toxicologists will make it easier for them to comply with ASTM E 1203 and therefore help to assure the quality of the toxicological data that they generate.