A New Army

Munitions and fleets of vessels dumped in waterways during the two World Wars may not be destined to become just waste after all: Researchers have found that a new army of diverse marine life has taken control of old Nazi warheads and US warships.

In two studies, German and US researchers have documented two examples of nature reclaiming the metal waste. The first study focused on a World War II munitions dumpsite in the Baltic Sea’s Lübeck Bay, while the second examined the “Ghost Fleet” in Mallows Bay, Maryland, where World War I ships were sunk in the 1920s.

Before the signature of the 1972 London Convention on the Prevention of Marine Pollution, unused explosive munitions were often dumped at sea. While the chemicals inside those objects are deemed highly toxic for marine life, their hard metal casings can provide stable surfaces for creatures to attach to and live on, according to a statement.

These relics can now provide marine biologists with a real-world look at how animals adapt to habitat disturbances, New Atlas wrote.

At Lübeck Bay, the team used a remotely controlled submersible to explore a recently discovered site of discarded WWII weaponry and equipment. They filmed the munitions and studied water samples from the site, while also analyzing two areas of the surrounding sediment for comparison. This dumpsite displayed warheads from V-1 flying bombs, the cruise missile used by Nazi Germany in late WWII.

Researchers found a far richer selection of wildlife living among the munitions than they expected, with 43,000 organisms per square meter on average, compared with about 8,200 organisms per square meter in the sediment around them.

These organisms seemed to have adapted to even high levels of toxins from the explosive compounds TNT and RDX, researchers said.

This discovery suggests that some creatures can tolerate high levels of toxic compounds if it gives them a safe, hard surface to live on. The animals were mostly seen on the casings rather than on uncovered explosive material, which the authors say could be a way for them to limit their chemical exposure.

While the munitions are an important habitat in the bay, the team said that replacing them with a safer artificial surface could be more beneficial to the local ecosystem.

The second study presented a high-resolution photographic map of all 147 wrecks currently found in the so-called “Ghost Fleet” of Mallows Bay, on the Potomac River, where the ships were deliberately sunk about 100 years ago. Their wrecks are now home to a wide variety of wildlife, like ospreys (Pandion haliaetus) and Atlantic sturgeon (Acipenser oxyrinchus).