Behavior of Autochthonous Microbial Communities, within a Deep-Sea Oil Plume, under In Situ Pressure

The response to oil contamination by autochthonous deep sea microbial communities has been largely studied using decompressed seawater samples, which are either repressurized or incubated at atmospheric pressure. However, the disturbance of microbial communities due to decompression results in loss of biodiversity followed by unknown effects on the function of microbial communities and, consequently, on overall hydrocarbon degradation rates.  Here, we used a novel high-pressure sampling and experimentation system to collect and incubate deep water microbial communities (600 -1000 m, off southern Crete) maintaining the in situ pressure during the whole process.  The undisturbed microbial communities were subjected to constantly low levels of oil contamination in a high-pressure bioreactor, emulating the conditions within a deep-water hydrocarbon plume. The early and long-term response of the microbial community to the disturbance and the degradation of hydrocarbons under high pressure were studied over a period of several weeks. The results of this study contribute towards a mitigation plan for accidental oil releases in deep-sea environments, tailored to the Eastern Mediterranean Sea.