Context: The North Sea hosts numerous historic shipwrecks. Two World War II vessels with ferrous hull were investigated, namely, a German Sperrbrecher 141 and Allied HMS Basilisk. Aims: Their disturbance of the coastal seabed was determined. More specifically, the microbial composition, diversity and introduction of iron, aluminium, sulfur and zinc was measured in marine sediment samples. Methods: Elemental analysis was conducted by microwaved-assisted HF destruction prior to inductively coupled plasma–optical emission spectroscopy (ICP-OES). Microbial characterisation involved the use of flow-cytometry, ATP spectroscopic assay and 16S rRNA amplicon sequencing .Key result: The wrecks cause enrichment in sulfur and largely varying iron concentrations (4.6–153 mg kg−1). Aluminium, which was less abundant, correlated to some extent with the bacterial cell density. Marine bacteria detected include Verrucomicrobiaceae, Woeseia and Flavobacteriaceae, next to sulfur and iron cyclers, similar to Desulfocapsaceae, Sulfurovaceae, Desulfuromonas and B2M28 that are active in dissimilatory iron reduction. Close to the wrecks, the alpha diversity in the seabed was significantly decreased. Conclusions: Hence, the submerged wrecks still alter the coastal sediment geochemistry and microbiology. Implications: Marine ecosystems near sunken war ships show an adaptive response that microbially cycle iron and sulfur, enriched in those environments. Results show special relevance to recent off-shore structures in coastal areas. |
