In the recent years, the exploration and exploitation of more and more inaccessible offshore deposits of hydrocarbons, has caused an increased concern for another deep-sea oil spill accident. Deep-sea bioremediation came to the fore after the Deepwater Horizon accident in the Gulf of Mexico in 2010. Subsea dispersant application and the live oil released at 1,500 m depth, resulted in the formation of small neutrally buoyant oil droplets, which remained underwater and formed subsurface plumes at depth, the largest and deepest of which was found between 1,000-1,200 m depth (“deep plume”). Dispersant application under high-pressure conditions to this day remains controversial and is still unclear whether it actually enhances oil bioremediation. Approximately 41% of hydrocarbons discharged during the DWH accident were entrapped subsurface and degraded by the autochthonous microbes, including the majority of the deep plume hydrocarbons. To this day there is little documentation regarding biodegradation rates to accompany the observed decrease in hydrocarbon concentrations related to microbial response. Most studies of oil biodegradation in the deep-sea are conducted under atmospheric pressure or by repressurizing the samples in the lab, thus providing non representative biodegradation rates.
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