Predicting survival of grass shrimp (Palaemonetes pugio) exposed to naphthalene, fluorene, and dibenzothiophene.

The composition and persistence of dissolved polycyclic aromatic hydrocarbons (PAHs) released to the water column during oil spills are altered by weathering, tidal transport, and addition of dispersants. Conventional toxicity effect metrics, such as the median lethal concentration (LC50), are inaccurate predictors of mortality from all toxicant exposure duration/concentration combinations likely to occur during spills. In contrast, survival models can predict the proportions of animals dying as a consequence of exposures differing in duration and intensity. Extending previous work with ethylnaphthalene, dimethylnaphthalene, and phenanthrene, survival time models were developed that include exposure duration and concentration to predict time to death for grass shrimp (Palaemonetes pugio). Two additional PAHs (naphthalene and fluorene) and a heterocyclic aromatic hydrocarbon (dibenzothiophene) were evaluated for the present study. Preliminary explorations of these models confirmed that quantitative structure- activity regression models were possible for predicting survival model parameters from compound characteristics. Conventional 48-h LC50s also were calculated for the compounds and combined with published LC50s to predict relative PAH toxicity to P. pugio based on octanol-water partitioning.