CHARACTERIZATION OF GRASS SHRIMP (PALAEMONETES PUGIO) EMBRYO TOXICITYTESTS USING THE WATER-SOLUBLE FRACTION OF NUMBER 2 FUEL-OIL

Toxicity test procedures using grass shrimp Palaemonetes pugio exposed to water soluble fraction (WSF) of Number 2 fuel oil were modified to improve test utility and efficiency. The original test procedure, a 1 2-day embryo exposure period in glass tubes, was compared with modifie d 4-day and 12-day tests in plastic tissue culture plates. Comparison of LC(50) values, coefficients of variation and time to hatch indicate d no significant change in test sensitivity due to the plastic contain ers, Sensitivity was slightly reduced by shortening the test to a 4-da y exposure period initiated 9 days after oviposition, This exposure pe riod encompassed sensitive life stages of the developing organism. Usi ng the 4-day exposure in plastic plates, variability due to different broods and preparations of WSF was characterized.