Toxicity of Gonyaulax tamarensis var. excavata cells to the brine shrimp Artemia salina L.

Brine shrimp (Artemia salina L.) were exposed to concentrations of live Gonyaulax tamarensis var. excavata cells ranging from 0 to 13,400 cells/ml in unialgal culture. The shrimp ingested the dinoflagellate cells and an LD50 determination was made. The shrimp had a 72-hr LD50 of 1258 G. tamarensis cells/ml, which was calculated to correspond to 73,385 micrograms/kg of body weight. This figure can be compared with an oral LD50 value of 2100 micrograms/kg for the mouse. Since it requires one-tenth as much toxin to kill a mouse (LD50 approximately 0.04 mg) as to kill an Artemia (LD50 approximately 0.4 mg), the whole cell G. tamarensis bioassay is a poor alternative to the current mouse assay.