Exposure system for coninuous controlled exposure of fish egg and larvae with dispersed oil

The current project addresses the need for parameterized data on long term toxicity of oil-in-water dispersions. In order to improve our understanding of the toxic impact of oil spills we must be able to: * Estimate the relative contribution of dissolved and particulate oil phases to toxicity. * Expand the time frame for toxicity tests with oil-in-water dispersions to include an evaluation of long-term toxic effects. * Provide data that can be used to predict photo-enhanced toxicity. The project covers th ese three topics, and the main objective is to provide basic methodology for highly controlled toxicity studies on fish egg and larvae exposed to oil-in-water dispersions. This methodology is needed in order to improve risk assessment input data in relati ng toxicological effects (acute and delayed) to the oil-in-water dispersion physio-chemical properties supplied by risk assessment models such as DREAM and OSCAR. At present risk assessments in the water column are based almost exclusively on the dissolve d fraction of oil. This is due to the lack of parameterized data that enables estimation of the relative toxicity contribution from the dissolved and particulate phases of oil in water. Oil droplets contain a relatively higher proportion of large aromatic compounds, such as PAH?s, than the dissolved phase. If these components are bio-available, oil droplets have a large potential for causing long term effects, either through direct toxic action, or by photo-enhanced toxicity through photo-sensitization. T he developed methodology will be tested on cod egg and larva.