A Nazi shipwreck that sank in the North Sea in 1942 is still polluting the surrounding seafloor with toxic chemicals eighty years later, but there are signs of sea life adapting to the wreck.
The wreck of the ship lies at a depth of about 115 feet (35 m) on the floor of the North Sea off the coast of Belgium.
The British warplanes in the North Sea sunk the Nazi patrol in 1942, and it is still leaking hazardous chemicals eighty years later, as published in the journal Frontiers in Marine Science on October 18th.
Pollutants from the historic shipwreck, including polycyclic aromatic hydrocarbons (PAHs) from its fuel, heavy metals, and traces of explosives, are affecting the microbiology and geochemistry of the seafloor around where the ship now rests.
Other Wartime Shipwrecks Could Leak Toxic Chemicals
Researchers suggest that the thousands of wartime wrecks in the North Sea between Britain and the European continent could similarly threaten the marine environment, according to the new study.
“The heavy metals can come from various sources—the metalwork inside the wreck itself can be a source of metal ions, as well as the fuel (coal), paint, and lubricants,” project leader Maarten De Rijcke, a researcher at the Flanders Marine Institute in Belgium, told Live Science.
“The PAHs and explosives are more clearly linked to the cargo of fossil fuels and munitions,” he added.
There are some signs, however, that marine life is adapting to the wreck, with some bacteria possibly eroding the sunken ship’s remains.
Position of the Shipwreck Profitable to Recreational Divers
De Rijcke said in an email that the wreck of the V-1302 John Mahn was chosen for the study because its position in the North Sea gives average hydrological conditions for the coast of Flanders.
It is away from shipping lines with good visibility at an accessible depth, and it was known to contain munitions, which had been mentioned by recreational divers.
He and his colleagues wanted to learn if such wrecks were still affecting the microbial communities and surrounding sediments of the seafloor where they lie.
This, therefore gives the researchers unique insight into the environmental threats they pose, according to a statement.
How the Nazi Boat Became a Shipwreck
After World War II broke out in 1939, The John Mahn, which was a German fishing trawler launched in 1927, was requisitioned by the German Navy (Kriegsmarine) under the Nazis as a “vorpostenboot,” or patrol boat, with the designation V-1302.
The Kriegsmarine based the vessel in the occupied Dutch port of Rotterdam, and it served in Operation Cerberus—a major naval action also known as the “Channel Dash.”
The vessel was part of a convoy escorting the heavy cruiser Prinz Eugen and the battleships Scharnhorst and Gneisenau through the English Channel to ports in Germany.
British bombers sunk the V-1302 John Mahn during action on February 12, 1942, and twelve of its crew members were killed while twenty-six others were rescued by German ships nearby.
The V-1302 John Mahn was the only German ship sunk during the action even though several other vessels were badly damaged during Operation Cerberus.
Other Shipwrecks From World War II Could Threaten Sea Environment
De Rijcke said the wreck is broadly typical of other World War II shipwrecks in the North Sea although some are much larger and could pose a greater environmental threat.
“The munitions and fuel found on this wreck were in common use across all Kriegsmarine ships,” he said.
He added that “a more heavily-armed destroyer or cruiser with the same munitions would be worth investigating, as our results show that the munition casings can be corroded.”
Results From Study Analysis of Nazi Shipwreck
In July 2020, the research team analyzed samples taken directly from the wreck’s steel hull and the surrounding seafloor and kept them frozen since then.
Their study revealed that while many of the chemicals were hazardous, all were well below toxic levels after eighty years beneath the waves. “At these concentrations, they are all harmless,” De Rijcke said.
The highest levels of metals like nickel and copper were found in the samples taken near the ship’s coal bunker—its supply of fuel—while the highest concentrations of PAHs were found in the samples taken closest to the vessel.
The analysis showed that the wreck had a relatively high level of biodiversity. Fish, crabs and crustaceans, molluscs, sea anemones, and marine plants, for example, use such wrecks as artificial reefs.
Analysis also showed microorganisms on and around the wreck were adapting to chemicals leaking from the vessel and that some were even using the metals as food.
“We see an increase of PAH-degrading bacteria near the coal bunker, indicating that some bacteria are benefitting from the availability of this chemical as a resource,” De Rijcke said.
Study of Nazi Shipwreck Part of a Project to Assess Environmental Risks
The study is part of a project to assess the environmental risks from sunken wrecks, which will allow governments to prioritize the most hazardous wrecks for closer inspection, he said.
Andrew Turner, an associate professor of marine and environmental biogeochemistry at the University of Plymouth in the United Kingdom who wasn’t involved in the study, explained that all sunken vessels release contaminants into the seawater, but the severity of the problem depends on how large the wrecks are and the particular chemicals involved.
“Unfortunately, we do not know how widespread the problem of sunken boats is,” he told Live Science.
Doug Helton of the Emergency Response Division of the National Oceanic and Atmospheric Administration (NOAA), however, said that although it could be expensive to assess the risk from a shipwreck, it would be less costly than dealing with an uncontrolled oil or chemical spill.
“Many are grave sites and historic, so caution is always advised,” he told Live Science in an email. “Some may be best left alone.”
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