Photo by Bernd Dittrich

Unexpected biodiversity on contaminated surfaces

Scientists using undersea submersibles have discovered crabs, worms and fish thriving on the surfaces of Second World War explosives in the Baltic Sea, finding more creatures living on top of warheads than in the surrounding seabed at a former weapons dump site.

Andrey Vedenin, study author from the Senckenberg Research Institute in Germany, said: “We were prepared to see significantly lower numbers of all kinds of animals. But it turned out the opposite.”

Scale of underwater munitions legacy

German waters alone contain about 1.6 million tonnes of dumped weapons, mostly from the two world wars in the 20th century. Dumped relics can contain nuclear and chemical remnants as well as explosives such as TNT.

In the new study, published in the journal Communications Earth and Environment, researchers filmed networks of anemones, starfish and other underwater life in the Bay of Lübeck off the coast of Germany. They were lurking on pieces of V-1 flying bombs used by Nazi Germany.

Hard substrate scarcity drives colonisation

The creatures could be drawn to the hard surfaces, which are in short supply in the Baltic Sea. The seafloor is mainly a flat bed of mud and sand because stones and boulders were fished out of the water for construction in the 1800s and 1900s, Vedenin said.

The area is also fairly isolated from human activity because of the chemicals, creating a somewhat protective bubble for the creatures to thrive despite some toxic trade-offs.

Research implications and future studies

James Porter, a University of Georgia ecologist who was not involved with the research, said: “Normally, one does not study the ecology of bombs.”

Scientists hope to calculate how much contamination was absorbed by sea life. Another important next step is to see what happens after the creatures settle and whether they are capable of reproducing, Porter said.

Broader pattern of wildlife adaptation

It is the latest example of wildlife flourishing in polluted sites. Previous research has shown shipwrecks and former weapons complexes teeming with biodiversity.

David Johnston, marine conservation biologist from Duke University, said: “I think it’s a really cool testimony to the strength of life.” He recently mapped sunken First World War ships that have become habitats for wildlife along the Potomac River in Maryland.

Studies such as these are a testament to how nature takes advantage of human leftovers, flipping the script to survive, Johnston said.