Dana at the Centre of a Cross-Disciplinary Mission to trace the massive Arctic change

The Rapid Change

Here, researchers made measurements to trace different types of freshwater. Some came from glacial melt, some from seasonal sea ice, and some from Siberian rivers feeding into the current thousands of kilometers upstream.

“When we look north, we see a region under rapid change, with warming and freshening of surface waters. Even a thin surface layer of freshwater can change how the ocean functions,” says Colin Stedmon and explains:

“It affects deep ocean mixing and the supply of nutrients, and the growth of phytoplankton that support the entire food web and contribute to ocean carbon dioxide uptake.”

Dana: Denmark’s Floating Research Hub across institutions

As Denmark’s national research vessel, Dana is a platform that makes it possible to unite expertise across disciplines and institutions. On this cruise, marine biologists studying plankton worked alongside geologists coring sediments, chemists sampling dissolved gases, and optical oceanographers measuring light in the water.

“This cruise was a very good example of cross-disciplinary cooperation,” Colin Stedmon says and stresses that:

“Dana is for every researcher in Denmark, and with cruises like this where ship time is supported by the Danish Centre for Marine Research, it allows us to work together in ways that simply wouldn’t be possible otherwise. That is becoming more and more important for Arctic research which really relies on a multidisciplinary effort.”

New Insights From the Deep: The Multibeam Debut

On this cruise, the multibeam helped researchers map more than 13,000 square kilometres of seafloor with unprecedented detail.

The multibeam was complemented by a sub-bottom profiler that revealed layers of sediments up to 50 metres beneath the seafloor. Together, the two systems provided a unique window into both present-day ocean conditions and the geological history of the Arctic.

“The multibeam gave us a completely new perspective,” says Colin Stedmon and continues:

 “We could see the ridges and valleys of the seabed and together with the sub-bottom profiler allowed scientists to target seafloor sampling sites much more precisely.”

Keeping data running with Argot floats

The results gathered on Dana will help researchers understand how Arctic freshwater affects the marine ecosystem and the global climate system. The data will also feed into models of ocean circulation and carbon cycling being developed in several EU financed projects that the cruise participants are involved in.

Another advanced instrument used in marine research and deployed in the cruise is the Argo float. Over the last four years, Colin Stedmon has been developing a national program as part of the Greenland Integrated Observing System project (www.gios.org).

During the cruise, the team deployed an Argo float in the Greenland Sea. These autonomous instruments drift with the currents and regularly dive to depth, measuring temperature and salinity profiles as well as being able to provide additional information about the sea.

The data are transmitted by satellite – thus, extending Dana’s observations long after the ship and the group of researchers participating in Denmark’s 2025 Atlantic-Arctic Ocean Change expedition left the region. In 2025, the researchers have deployed 6 floats in the Arctic and they can be followed online.

For Colin Stedmon, the cruise underlined both the scientific challenges ahead and the strength of Denmark’s shared investment in Dana:

“We need to understand these changes, because they affect us all, and a better understanding will allow us to understand how and be prepared as climate change progresses.” he says. “A national vessel such as Dana gives us the best possible platform to do that — by bringing together people, knowledge and technology on one ship, and allowing Danish scientist to ensure the most relevant research agenda is addressed.”