Characterization of grass shrimp (Palaemonetes pugio) embryo toxicity tests 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 12-day embryo exposure period in glass tubes, was compared with modified 4-day and 12-day tests in plastic tissue culture plates. Comparison of LC50 values, coefficients of variation and time to hatch indicated no significant change in test sensitivity due to the plastic containers. Sensitivity was slightly reduced by shortening the test to a 4-day exposure period initiated 9 days after oviposition. This exposure period encompassed sensitive life stages of the developing organism. Using the 4-day exposure in plastic plates, variability due to different broods and preparations of WSF was characterized.