USE OF BRINE SHRIMP ( ARTEMIA) IN DISPERSANT TOXICITY TESTS:SOME CAVEATS

摘要

Several Latin American countries currently useArtemia to evaluate the aquatic toxicity of dispersants. Testmethods used to evaluate dispersant toxicity to Artemia are notuniform. The study reported here demonstrates how varyingArtemia test conditions can significantly affect toxicity results forthe dispersant Corexit? 9500.The type of seawater used in Artemia toxicity tests affects 48hour LC50 values for Corexit 9500 (lethal concentration for 50%of test organisms). Nominal LC50 values ranged from 35 to 147ppm when natural seawater was used. Nominal LC50 valuesranged from 29 to 39 ppm when a synthetic seawater preparedfrom Crystal Sea? Marinemix was used. Greater toxicity wasobserved when synthetic (reconstituted) seawater was preparedaccording to the U. S. Environmental Protection Agency(USEPA, 1987) Artemia dispersant test guideline. Observednominal LC50 values ranged from 8.4 to 14 ppm.Age of the Artemia nauplii is another test variable that cansignificantly affect toxicity results. The 48 hour nauplii showedgreater toxicity to Corexit 9500 than 24 hour old nauplii. In testsusing two types of synthetic seawater (Coral Reef Red Sea Salt?and Crystal Sea? Marinemix at 20 °C, 20 ppt salinity), nominalLC50 values ranged from 29 to 68 ppm for 24 hour old nauplii; 48hour old nauplii had LC50 values ranging from 9 to 27 ppm.Greater toxicity was also observed in 48 hour nauplii underdifferent salinity and temperature (Red Sea, 25 °C, 33 to 35 pptsalinity). The LC50 values were 33 and 1.6 ppm for 24 and 48hour nauplii respectively.