Discarded World War munitions and shipwrecks have unexpectedly become the foundation of new undersea ecosystems, with one site even supporting more life than the surrounding seafloor, according to new research.
The findings were revealed in a pair of new papers published in the journals Communications Earth & Environment and Scientific Data. One study focuses on discarded World War II munitions in the Baltic Sea, while the other examines shipwrecks off the coast of Maryland in the United States.
Together, the research shows how, despite their toxicity, remnants of human conflict provide hard surfaces that many marine species choose to inhabit.
A Toxic History
Governments were not always aware of the dangers posed by environmental pollution. Routine dumping of unused ammunition at sea continued until the 1972 London Convention on the Prevention of Marine Pollution banned the practice. The munitions dumped prior to the treaty remain in a delicate balance for marine life: their interiors contain harmful chemicals, but those chemicals are often sealed within hard metal casings—the kinds of surfaces that many species prefer to colonize.
In the Baltic study, researchers deployed a remotely operated submersible drone in Lübeck Bay, the site of a recently discovered World War II munitions dump. Drone footage and water samples were collected, along with data from two surrounding patches of sediment.
Analysis revealed that the munitions were Nazi V-1 warheads, among the most advanced weapons of their era. The devices, used in the bombing campaign against London, were often referred to as “buzz bombs” because of the distinctive sound they produced.
World War Ecosystem
Despite their destructive history, the discarded warheads now harbor thriving ecosystems. The dump site contained an average of 43,000 organisms per square meter, compared to just 8,200 organisms per square meter in the surrounding sediment. The key factor is the presence of hard surfaces, a trend observed in other studies comparing natural hard surfaces with adjacent sediments.
Toxicity levels within the dump site varied widely. Some areas showed only trace amounts of explosive compounds—as low as 30 nanograms per liter—while others reached 2.7 milligrams per liter, a concentration potentially lethal to marine life. The chemicals, primarily TNT and RDX, remain dangerous, although researchers observed that organisms tended to colonize the safer hard outer casings rather than exposed explosive material.
The team concluded that while these artificial habitats support marine life, long-term preservation of healthy ecosystems may require removing the munitions and replacing them with safer hard substrates.
Ghost Fleet Habitat
Lying off at the bottom of the Potomac River’s Mallows Bay are a group of 147 ships referred to as the “Ghost Fleet,” remnants of the US fleet from World War I. Outliving their usefulness, the vessels were disposed of by setting them ablaze and allowing them to sink in the river in the late 1920s. Today, those decaying hulls are home to ospreys, Atlantic sturgeon, and other aquatic wildlife.
David Johnston led a team in developing a high-resolution photographic map that catalogs the locations of each ship. Using drones in 2016, they stitched together thousands of aerial photographs to produce the new map.
Unlike the Baltic Sea project, this work emphasizes historical and archaeological research as much as biology. Nonetheless, it represents a first step toward the kind of detailed ecosystem analysis carried out in Lübeck Bay.
The paper, “Sea-Dumped Munitions in the Baltic Sea Support High Epifauna Abundance and Diversity,” appeared in Communications Earth & Environment on September 25, 2025, and the second paper, “Mapping the ‘Ghost Fleet of Mallows Bay, Maryland with Drone-Based Remote Sensing,” appeared in Scientific Data on September 25, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.