Environmental risks from world war shipwrecks: Field-based biomarker evidence from caged mussels in the North Sea

The two world wars have left a toxic legacy in the oceans, which emerges as a new environmental problem. There are several thousand war wrecks around the world that are still partially or fully loaded with munitions. This issue is common in the waters of the North Sea. Decades of exposure to a saline environment promoted the corrosion of ship hulls and munition casings, allowing the munition compounds to be released. Many of these chemical compounds, especially the most significant explosive in quantity, 2,4,6-trinitrotoluene, better known as TNT, are toxic and threaten the marine environment and its organisms. While most studies on biological effects work with very high concentrations not found in the environment, this study focuses on field trials. To investigate the risk to the environment from wrecks loaded with munitions, experiments were carried out with blue mussels, Mytilus edulis, on three wrecks in the North Sea. Mussels were exposed in cages on shipwrecks for several weeks and examined for changes in the enzyme activity involved in detoxification processes, such as the Antioxidant-Defense System, and changes in the accumulation of metabolites. Significant differences can be seen in the activity of the enzymes involved in detoxification processes. There are different rates of accumulation of metabolic end products in the lysosomes of the mussel digestive gland, indicating negative impacts emanating from munitions-laden wrecks. The findings from the cage experiments underline the need for monitoring munitions remains and polluting shipwrecks in the oceans in the future to find the most effective solution for marine ecosystems worldwide.