Nazi Submarine Is Being Destroyed by Oil Spill-Fueled Sea Bacteria

German U-boat 166 has been lying at the bottom of the Gulf of Mexico since it was sunk by the U.S. Navy during World War Two. For nearly 80 years, the bacteria in those waters have exacted their revenge upon the vessel, chewing it away piece by piece. In 2010, they became even more voracious, scientists report.

In its lifetime, U-166 was a Nazi submarine that patrolled U.S. waters and destroyed four vessels. After it was finally sunk in 1942, it was lost until 2001, when it was rediscovered as part of a pipeline survey. Since then, conditions have deteriorated around the wreck. When the Deepwater Horizon oil rig exploded in 2010, it released a plume of oil equivalent to 4 million barrels into the waters surrounding the submarine.

In a paper published earlier in February in Frontiers in Marine Science, a team of scientists at the University of Southern Mississippi argue that the oil spill changed the microbial communities living on the wreckage of the sub, causing it to disintegrate more rapidly than ever.

The team, led by Leila Hamdan, Ph.D., an associate professor microbial ecology, says that U-166 is falling prey to microbial-induced corrosion, which is when tiny communities of microbes form on metal surfaces and eat away at the available molecules that those surfaces provide. As the microbes flock to sunken ships or submarines, they form biofilms — communities that work together — and degrade the metal surfaces they inhabit over time.

Hamdan and her colleagues think the Deepwater Horizon oil spill actually changed the microbe species that make up those biofilm communities. When the seawater around U-166 was flooded oil, different and hungrier types of bacteria were able to thrive.

“Time series images reveal that metal loss at a heavily impacted site, the German Submarine U-166, has accelerated since the spill in 2010,” the authors write. “This study provides evidence that spill residues on the seafloor may impact biofilm communities and the preservation of historic steel shipwrecks.”

Hamdan and her team confirmed their theory by placing carbon metal disks around five different wreckage sites within the Deepwater Horizons plume: three World War Two-era ships (including U-166) and two 19th-century ships. After 16 weeks, they found the most disk degradation at U-166 (corroborating images of the disintegrating submarine over the years) and noted that the disks cultivated a wide array of bacterial species, including “oil-degrading bacteria” that eat the sulfur in crude oil. Adding to the degradation, they note, these bacteria actually generate by-products (metabolites) that can accelerate the corrosion of metals — like the discs, or the metal that makes up U-166.

"Given the historical and cultural significance of the U-166, we should go back.

In a sense, these oil-eating bacteria might be serving the Nazi submarines some poetic justice. Images of U-166 from 2003, 2009, and 2013 show that the ship lost five times more metal in the four years after the New Horizons spill than it had in the six years preceding the spill. Not that these bacteria are only out to get Nazi wrecks: other ships made of similar materials may take a hit too, the authors note.

Still, the historical importance of U-166 shouldn’t be underestimated, as Hamdan noted in an interview with New Scientist.

“Given the historical and cultural significance of the U-166, we should go back,” Hamdan said. “The deep sea is a place that not a lot of us can connect with and this gives us a reason to care.”

In light of its dark history, it’s hard to see U-166 as a victim in any sense, though the disastrous oil spill behind its degradation is definitely no white knight, either. As the seafloor bacteria eat the wreck away, it’s a testament to more than one of humanity’s worst tendencies.