The OSCAR model simulates biodegradation for 25 selected oil pseudo-component groups, separated on the bases of boiling point characteristics, by using a database of first-order biodegradation rate coefficients (k1) ( Reed et al., 2000). The same database is used in geographically and climatically different areas. It is well known that HC biodegradation depends on several environmental factors other than temperature, that vary considerably among marine environments, e.g. nutrient concentration, salinity, and type of oil degraders ( Leahy and Colwell, 1990). In general, a few keystone genera are typically identified in oil exposed marine environments, such as Alkanivorax and Cycloclasticus ( Head et al., 2006; Yakimov et al., 2007). However, quantitative data describing biodegradation rate of these bacteria are usually not reported, hence it is yet unclear to what extent the geographical origin of these HC degraders can affect observed biodegradation rates. Due to lack of established quantitative relationship between degradation rates and these factors (e.g. nutrients and type of degraders), mathematical formulation is not implemented in the OSCAR model. The relationship between temperature and biodegradation rate has been established (Equation (2)) and implemented in the OSCAR model as follows. Location specific biodegradation rate coefficients are calculated by the OSCAR model from the database of reference k1 values based on the temperature difference between the incubation temperature where reference k1 values were measured and the ambient temperature of the environment where the OSCAR model is applied, according to: