On Mays 3, 2025, the research vessel “Elisabeth Mann Borgese” departed from Rostock for this year's Baltic Sea spring monitoring expedition, EMB 365. On board: a 10-people IOW team of researchers, laboratory and technical staff, who will carry out the measurements and sampling.

The three-week cruise will include work at more than 100 sampling stations. The scheduled programme comprises high-resolution physical and hydrographic measurements, sampling for chemical analyses of nutrients and pollutants, phytoplankton and zooplankton sampling, and the deployment of autonomous measuring buoys. Since 2024, the spring cruise also includes measurements as far out as the Gulf of Bothnia in addition to the usual measurement programme of the five annual monitoring cruises to the central Baltic Sea to broaden the monitoring scope to the entire Baltic Sea.

"Last year, sea ice prevented us from actually visiting all of the stations planned along the extended northern route. After the mild winter, we are confident that we will be able to carry out the full measurement programme this time," says IOW oceanographer Volker Mohrholz, who is the chief scientist on the current expedition. In Umeå, Sweden, the "Elisabeth Mann Borgese" will take two Swedish researchers on board: Nina Dagberg and Anna Palmbo Bergman from the Marine Science Center at Umeå University will accompany the IOW team for a week to carry out their own measurements as part of the university's long-term measurement programme, which has been in place since the early 1990s. "We are looking forward to working with our Swedish colleagues, as we all benefit from such collaborations between researchers from the Baltic Sea littoral sates," says Volker Mohrholz. This year's spring monitoring cruise ends on May 24 in the Rostock home port of the "Elisabeth Mann Borgese".

The EMB 365 expedition is part of the IOW monitoring and long-term data programme, which has been in operation since 1969 and was officially recognised by the United Nations last year as a project of the ‘UN Decade of Oceanography for Sustainable Development’ (more information here). The long time series allow to analyse and describe the state of the Baltic Sea both in the past and present, as well as to make statements about its possible future. Here, the main focus is on eutrophication, pollution and climate change with its consequences for the Baltic Sea ecosystem. The data obtained are freely available to the scientific community and form the scientific basis for policy advice at regional and national level.