Duration: 19 August to 20 September 2025

Area: North Sea and Baltic Sea

Purpose: Biological effects monitoring in the North and Baltic Seas

The 492nd voyage of the Walther Herwig III is dedicated to studies on the biological effects of pollutants in the North Sea and Baltic Sea within the framework of national legislation and measurement programmes (Radiation Protection Act, Federal and State Measurement Programme (BLMP)), international agreements (Oslo-Paris Agreement for the Protection of the North Sea and the North-East Atlantic (OSPAR 1992), Helsinki Convention for the Protection of the Baltic Sea (HELCOM 1992)) and various research projects currently underway at the Thünen Institute. Radioactive substances, heavy metals and organic pollutants and their effects on biological systems are to be analysed.

The following tasks are pending:

• Collection of fish samples for the analysis of radioactive substances, heavy metals and organic pollutants using bottom trawls and pelagic trawls
• Removal of livers and other organs from fish for subsequent histological and biochemical examinations
• Taking water samples and using probes for hydrographic determinations of salinity, temperature and oxygen using a crane water sampler with CTD probe and oxygen sensor (CTD = probe for measuring conductivity, temperature and depth)
• Collection of water samples for analysis for environmental DNA (eDNA) using a crane water sampler
• Taking sediment samples using a Van Veen grab
• Direct measurements of the contamination of various matrices using an ROV-supported gamma spectrometer (ROV = remotely operated underwater vehicle)
• Video recordings of rubbish on the seabed with an epibenthos sledge (epibenthos = organisms living on the seabed)