In the aftermath of natural or accidental releases of crude oil in the sea, part of the oil ends up in clouds of droplets that travel along with underwater sea currents and disperse deep into the oceans. The droplets may be created either at the sea surface during the breakup of floating oil layers by sea waves, or at the seafloor during the extrusion of crude oil from natural cracks and broken wellheads. In spite of the frequent and extended contamination of marine waters with hydrocarbons from surface and deep-sea oil spills, including massive spills like the Ixtoc I (1979), Exxon Valdez (1989), Prestige (2002) and many others, the occurrence and significance of underwater droplet clouds was only discovered during the recent Deepwater Horizon event (2010).
Since then, numerous studies have demonstrated that excessive amounts of dispersed oil droplets in seawater disturb the established dynamics of the local ecosystem (e.g. carbon cycle, marine microbiome structure, micronutrient and oxygen depletion, marine snow blooms). On top of that, when microsized oil droplets are ingested by fish and other marine animals, not only they pose an imminent risk of toxicity to the animals but also might go up the food chain and end on the plate of humans. At present, there are no practical means for the collection or in situ treatment of oil droplets in vast bodies of marine waters and, thus, the lifetime of underwater droplet clouds is determined by natural attenuation processes, mainly dissolution into the seawater and biodegradation by oil-eating microbial communities.
It is therefore imperative to understand and quantify the physical and biological mechanisms that rule the fate of dispersed oil droplets in marine waters and, upon that knowledge, build technologies that will enable the mitigation of pertinent adverse effects. The overarching scope of the OILY MICROCOSM project is to obtain an improved understanding of the fundamental microscale mechanisms that underpin the biodegradation of droplet clouds by microbes at both the single-droplet and droplet-population levels through a creative combination of microfluidics, advanced imaging and computational modeling.
