Impact and restitution model - Water column. ERA Acute for water column exposed organisms

Abstract

Exposure to oil components in the water column in ERA Acute can be modelled using either of two alternative options in the oil spill model OSCAR. While the option based on the Critical Body Residue (CBR) takes changing oil properties/toxicities and exposure time into account and therefore represents a scientifically more valid approach, an alternative and more conservative option based on the modelled maximum total hydrocarbon (THC) concentrations over the whole water column is also described. A global fish restitution model has been developed based on historical recruitment data, and demonstrating strong links between the climatic regime and natural fluctuations of fish stocks. Restitution modelling shows that as long as impact is assessed on the reproductive unit (spawning stock), even a major oil spill will not have a measurable effect on fish stocks. Higher risk may apply if fish larvae are considered representing a valuable resource in itself, e.g. as a planktonic food source of predating organisms, but this is not within the scope of this project.