Faroe-Shetland Channel could face Deepwater Horizon ‘dirty blizzard’

A deep water oil spill in the northeast Atlantic would be more difficult to combat than the Deepwater Horizon spill of 2015, and the use of a dispersant in those waters would create a subsea ‘dirty blizzard’ of marine oil snow, according to scientists. 

When tackling oil spills, operators often use dispersants, which break up the oil and encourage it to degrade naturally.  The new research from Heriot-Watt University, published in Frontiers in Microbiology, shows that the use of a dispersant in the Faroe-Shetland Channel after an oil spill would trigger conditions similar to the aftermath of Deepwater Horizon: the formation of marine oil snow (MOS). 

MOS comprises sticky, floating organic particles that are visible to the naked eye and contain oil droplets from spills. MOS sinks rapidly, which has two effects: it vanishes much of the oil from the surface, leading observers to think the spill has been cleaned up, and it carries the oil to the seabed, with potentially damaging effects on deep sea ecosystems. 

The rapid sinking of copious quantities of MOS to the seabed was the ‘dirty blizzard’ that occurred during the Deepwater Horizon spill, and may have accounted for vast quantities of oil that impacted much of the continental slope in the northern Gulf of Mexico around the Macondo wellhead. 

Dr Tony Gutierrez, Associate Professor of Microbiology at Heriot-Watt University, said, “Many lessons were learned from the Deepwater Horizon oil spill. 

“The Faroe Shetland Channel is at the frontier of deep water petroleum exploration, so there is a pressing need for fundamental research in this region. 

“The area is already home to oil rigs that are extracting oil at depths of down to 500m, and the region is being scoped for oil at much greater depths. 

“The Faroe-Shetland Channel is the ‘spaghetti junction’ of Icelandic, Norwegian and Atlantic currents and is much more hydrodynamic than the Gulf of Mexico, where the Deepwater Horizon spill occurred. 

“The possibility of a deep sea spill in this area in the future cannot be discounted, so it’s vital we know how to respond.

“Our research is a first step to understanding the fate of oil in the event of a major spill in the Faroe Shetland Channel.

“We don’t know exactly what happens when the MOS arrives on the seabed, but given the fragility of sponge belts in the Faroe-Shetland Channel and other sensitive benthic communities, it’s not likely to be good.” 

Laura Duran Suja, a PhD student at Heriot-Watt University, led the study and took surface seawater samples from the water mass known as the Modified North Atlantic Wester (MNAW), near the Schiehallion oil field, and incubated them with the oil under conditions simulating the sea surface.

Over the course of six weeks she studied the microbial response, including of the oil-degrading bacterial communities, and observed the formation of MOS in incubations treated with dispersant and/or nutrients. 

Dr Gutierrez said: “Our data indicates that in the event of an oil spill in the Faroe Shetland Channel, the use of dispersants could trigger the formation of MOS. The good news is that the MOS harbours rich communities of oil-degrading bacteria, which have an important role in ‘eating’ up the oil. 

This work is the first of its kind to test dispersants on the microbial response and formation of MOS in the event of an oil spill in the Faroe Shetland Channel. Dr Gutierrez cautions that more work is needed to understand existing dispersants and develop safer, more effective products to combat oil spills and minimise impacts to pelagic and benthic ecosystems in the area.