Fate of petroleum hydrocarbons in marine animals

The concentration of hydrocarbons in marine animals exposed to oil reflects the relative importance of uptake, metabolism, storage and discharge. Crabs, worms and fish have a detoxification system in the liver or intestinal tract which degrades aromatic hydrocarbons to hydroxylated derivatives. Compared with the parent hydrocarbon, hydroxylated derivatives are more water-soluble and are released by the animals. Thus metabolic pathways help to reduce the level of hydrocarbon in the animal. The process is sometimes referred to as a detoxification mechanism. Third generation worms chronically exposed to oil are resistant to oil, presumably because they contain high levels of hydrocarbon degrading enzymes. Bivalves, including clams, oysters and mussels, do not possess this enzyme system and tend to accumulate hydrocarbons to a greater extent than other marine animals. Because of this fact it has been suggested that they can be used to monitor ocean waters for petroleum pollution.