Sea-dumped munitions in the Baltic Sea support high epifauna abundance and diversity

Abstract The German waters contain 1.6 million tons of munitions, mostly dumped after the World Wars. The structure and composition of epifauna were investigated on the dumped munition in the Lübeck Bay (Baltic Sea) within the area with regular hypoxic conditions using a remotely operated vehicle (ROV). Objects were identified as warheads from the Fieseler flying bomb (Fi103, known as V1). Eight species of epifauna were found, with a mean density of 43,184 ind. m −2 , mostly concentrated on the metal parts. Surrounding sediment had a significantly lower abundance of only 8213 ind. m −2 . Chemical analysis of water sampled directly near several warheads showed high concentrations of explosive compounds, with, e.g., trinitrotoluene (TNT) levels of 2.73 mg/l. These concentrations approach toxicity thresholds for aquatic organisms. However, the epifauna develops on breached munitions in numbers comparable to natural hard substrata. In the future, munitions should be replaced with safe, hard substrates.