PS144: 20 year SUITing in the ice
It was a crazy idea that was viewed with skepticism by many researchers: A research net that glides along the underside of the ice and captures the small animals living there. But the Dutch ornithologist Jan Andries van Franeker was convinced that a new approach was needed to solve a paradox in the Antarctic ecosystem: Using traditional methods, there was simply not enough krill, fish and zooplankton in the deeper water layers of the Antarctic Ocean to meet the food requirements of the numerous seals, birds and whales deep in the Antarctic pack ice. Van Franeker was convinced that krill and other small animals living at the underside of the pack ice were crucially important to the birds and marine mammals, but the inaccessible habitat under the ice could not be sampled using conventional methods. So, in 2003, a small group of technicians and scientists at the Alterra Institute (now Wageningen Marine Research, WMR) on the Dutch island of Texel set out to develop a research net that could be used to sample the underside of the ice, the Surface and Under-Ice Trawl (SUIT). In addition to van Franeker, Koos Zegers, André Meijboom and Michiel van Dorssen were involved in the initial designs. I was to write my doctoral thesis on the results obtained with the SUIT, and participate in its first expedition with Polarstern, ANT XXI-4.
The SUIT consists of a kind of under-ice sledge made of heavy steel tubes, which is held on the surface by drivers and pulled by an icebreaker. A special bridle causes it to move sideways behind the ship and rubber wheels on the top ensure that it slides under the ice. The SUIT was built by Texel metalworker Michiel van Dorssen. In the spring of 2004, it was deployed for the first time from the icebreaker Polarstern in the Antarctic pack ice. The first missions were difficult and yielded of criticism and malice from the other researchers on board. I saw my doctoral hat sink into the icy ocean. The SUIT quickly got its nickname among the crew: the “Kampfwagen” (battle wagon). It was only when Polarstern officer Uwe Grundmann (see picture) developed a system that made it possible to safely launch and retrieve the Kampfwagen ‘, that it became clear that the SUIT could bring to light a unique community of life under the pack ice. Yet, without the scientific support of the cruise leader Ulrich Bathmann from the AWI, there would probably never have been more than these first attempts.
Night deployment of the SUIT net, which can dive under the sea ice to catch organisms living underneath the sea ice. (Photo: Jan van Franeker)
In the end, I was able to complete my doctoral thesis. And it was not to be the only one. On the current Polarstern expedition PS144 “ArcWatch-2”, we have now deployed the SUIT for the 246th time in both polar regions. Of all things, a winter expedition with Polarstern under the most adverse conditions in the Antarctic holds the record for the most SUIT deployments: Stefan Schwarze (see picture) and his crew made 32 under-ice samplings possible. In addition to the Polarstern, the Australian Aurora Australis, the Japanese Kaiyo Maru and the US American Sikuliaq have also used it. To date, eight further doctoral theses, numerous bachelor’s and master’s theses and over 40 scientific publications are based on samples and data from the SUIT. One of the most important results was the proof that the majority of krill stocks in the Antarctic are often found in the mostly ice-covered upper two metres of the ocean, where they could not be detected by conventional methods. In the Arctic, the SUIT helped to trace the migration patterns of the ecologically important polar cod under the sea ice. Finally, with the help of chemical-physical analyses, it was also possible to prove that the small animals on the underside of the ice play a key role in the Arctic and Antarctic food webs by taking up carbon from ice algae and transferring it into the polar ecosystems via the food chain. The SUIT is now not only used for biological research, but also provides unique data on the physical properties of the sea ice and the under-ice habitat thanks to a range of modern sensors.
The SUIT team from 2004 (Photo: Jan van Franeker)
Over the past 20 years, the Kampfwagen has made a small contribution to research into the role of sea ice in polar ecosystems, and thus also to understanding the changes we can expect as a result of the ice melting that was caused by the man-made climate crisis. Sometimes it is worth pursuing a “crazy idea” against all odds. To the very least, it can bring surprising insights and results.
