Toxicity tests results for oil and dispersant preparations

The influences of oil in water preparation on the toxicity of crude oil to marine invertebrates and fish following short-term pulse and continuous exposures- this is the data that supports this paper.\n\nFollowing an oil spill, accurate assessments of the ecological risks of exposure to compounds within petroleum are required, as is knowledge regarding how those risks may change with the use of chemical dispersants. Laboratory toxicity tests are frequently used to assess these risks, but differences in the methods for preparation of oil in water solutions may confound interpretation, as may differences in exposure time to those solutions. In this study, we used recently developed modifications of standardised ecotoxicity tests with copepods (Acartia sinjiensis), sea urchins (Heliocidaris tuberculata) and fish embryos (Seriola lalandi) to assess their response to crude oil solutions and assessed whether the oil-in-water preparation method changed the results. We created a water-accommodated fraction (WAF), chemically enhanced water-accommodated fraction (CEWAF) and a high-energy water-accommodated fraction (HEWAF) using standard approaches using two different dispersants, Corexit 9500 and Slickgone NS. We found that toxicity was best related to total polycyclic aromatic hydrocarbon (TPAH) concentrations in solution, regardless of the preparation method used, and that the HEWAF was the most toxic because it dispersed the highest quantity of oil into solution. The TPAH composition in water did not vary appreciably with different preparation methods. For copepods and sea urchins, we also found that at least some of the toxic response could be attributed to the chemical oil dispersant. We did not observe the characteristic cardiac deformities that have been previously reported in fish embryos, most likely due to the use of unweathered oil, and, as a consequence, the high proportion of naphthalenes relative to cardiotoxic PAH in the overall composition. This study highlights the need to characterise both the TPAH composition and concentration in test solutions when assessing oil toxicity.