HE 669 CONMAR – REMARCO

27/09/2025

3 minutes

The research cruise HE 669, conducted jointly by REMARCO and CONMAR, took place from 27 September to 10 October 2025 and led a multidisciplinary team from Bremerhaven across several regions of the North Sea before returning to port.

CONMAR is a national research initiative funded by the German Federal Ministry of Education and Research that investigates the ecological risks posed by dumped munitions in marine environments and develops the scientific foundation for future remediation and management strategies.

Scientists from five institutes, the Alfred Wegener Institute (AWI), the Max Planck Institute for Marine Microbiology (MPI), the Senckenberg Institute at Sea, the Flanders Marine Institute (VLIZ), and the German Maritime Museum (DSM), worked together to investigate the presence, distribution, and ecological effects of explosive residues originating from munition dumping sites. The central aim of the expedition was to determine how explosive compounds enter and move through the marine environment and whether they accumulate within the North Sea food web.

During the cruise, five key areas were sampled: the wreck of MS Brummer in Norwegian coastal waters, the wreck of Vigo in German waters, the munition dumping sites near Sylt and Helgoland Steingrund, and a reference area near Borkum Riffgrund presumed to be unaffected by munition-derived contaminants. At all sites except MS Brummer, fish were collected to determine whether explosive residues can be detected in their tissues. These chemical analyses will be carried out by the University Hospital Schleswig-Holstein (UKSH), while AWI will investigate potential biological effects triggered by explosive compounds.

Benthic samples were collected using a van Veen grab and processed for macrofauna, sediment characteristics, and chemical analyses of explosive compounds. Both organisms and sediments were preserved or frozen directly on board to ensure high analytical quality. Additional organismal samples for chemical residue analyses were also provided to UKSH.

Beyond benthic sampling, the expedition gathered a wide range of materials for complementary research across the participating institutes. VLIZ collected sediment for microbial analyses, focusing on community composition and metabolic potential. Water samples from multiple depths will help quantify dissolved and particulate munition residues and provide insights into their transport pathways within the water column.

AWI and Senckenberg collected fauna from various trophic levels to assess potential bioaccumulation and toxicological impacts. Fish samples will undergo detailed health assessments, including histology, cellular analyses, and biochemical assays targeting detoxification processes and oxidative stress. Additional measurements will evaluate metabolic performance and overall organismal condition. Combined with tissue-residue data, these analyses will reveal whether contaminants move through the food web and whether exposure causes physiological stress.

Despite several days of rough seas and challenging weather, all planned stations were successfully sampled, and the teams returned to Bremerhaven with freezers and refrigerators filled with valuable samples. The coming weeks will be dedicated to processing and analyzing the extensive sample collection. Scientists from all collaborating institutions will integrate microbial sequencing, chemical analytics, ecological data, histopathology, and biomarker measurements to develop a comprehensive picture of how explosive residues affect the North Sea ecosystem, from microbes in the sediment to top predators.

The findings of HE 669 will make an essential contribution to ongoing efforts to understand and mitigate the environmental legacy of underwater munitions. As analyses progress, more insights will follow. Stay tuned as our research teams dive deep into the data. For further insights into the fauna analyses conducted within the project, head over to CONMAR to explore their upcoming results.