The Polarstern slowly nears its goal: a point in the middle of the Atlantic, 191 nautical miles south of the Cape Verde islands. No coast is in sight. The bathometer, however, indicates that this is the right place. 4,884 metres below the ship’s hull, the seabed abruptly descends into an abyss. On this slope of the African Continental Shelf, Peter Wiebe wants to start making his catch.
The biologist from the US American Woods Hole Oceanographic Institute is nervous. Frantically he again walks round the heavy metal frame lying on the planks like a fallen door-frame. He tests to see if the steering elements are adjusted and the 16-metre-long net bags made of fine gauze are hanging freely one behind the other. Then Wiebe waves to the petty officer at the crane: Everything ready! MOCNESS, the special net, can be lowered into the water. The 26 marine biologists and two dozen members of the ship’s crew watch as the 300-kilogram catching device sinks into the waves as its five net bags, which can be opened and closed by remote control in the different depths of the ocean, rise up out of the water once again like whales’ backs only to then glide on the metal frame into a dark and ice cold cosmos that is as inaccessible to humans as space: the deep sea. There, MOCNESS is to search for unknown tiny animal species, zooplankton. These include little crabs and snails, bristle worms, arrow worms and jellyfish. The marine biologists left Bremerhaven for Cape Town in South Africa to gather data for a gigantic “census” along a 12,000-kilometre long research transect, a series of previously determined examination points. In the Census of Marine Life researchers from more than 80 countries record what kind of creatures populate the oceans, how many microbes and molluscs, fish and sea mammals are distributed in the waters.
The core of such large international projects is formed by the marine expeditions with their multinational teams, and the Polarstern plays a decisive role in these. The icebreaker of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven has been in the service of science, 320 days a year for almost 30 years. The ship’s owner is Germany, represented by the Federal Ministry of Education and Research. The Polarstern steers its course through rough seas and pack ice – driven by five eight-cylinder diesel engines with a total of 20,000 horsepower. On almost all its expeditions, it takes researchers to the polar regions, and on such occasions every place on board is highly sought after, given that the Polarstern is regarded as the strongest polar research ship in the world. A large floating laboratory equipped for almost every kind of polar and marine research, for example, oceanography, climate research and biology.
More than 100 researchers, technicians and crew members find bunks in the cabins, space to experiment in nine laboratories and the necessary equipment on eight different levels of the ship. Like Peter Wiebe, for example, who would not be able to dispatch his nets into the depths without the ship’s own state-of-the-art technology. South of the Cape Verde islands the American biologist studies the computer screen to see how his monstrous machine slowly approaches the ocean bed: down through almost 5,000 metres of water until it is cruising at about 100 metres above the deep-sea floor. With the click of a mouse, Wiebe then opens the lowest net bag and slowly pulls in the frame with the receptacles. A good 13 hours later it pops up again in the azure blue sea thanks to the ship’s winches. Now things have to happen fast, for the captured creatures, which are accustomed to the cold of the deep sea, could die within minutes on board. In the cold laboratory, the researchers spread out their catch in dishes and start their examinations. Over a period of four weeks the nets are cast from the Polarstern. When the ship anchors in the harbour at Cape Town, the journey is over for the marine biologists working on the Census Project, while the icebreaker’s journey then really only gets started. A new crew of international scientists gets ready for their destination: the Antarctic.
The Polarstern ploughs through the Atlantic Ocean into the Antarctic Ocean as it does every year between November and March, bringing researchers into Antarctic waters or onto dry land and delivering food, warm clothing, sleighs, tools and other technical equipment to the teams at the German Antarctic research base Neumayer Station III. Once the researchers on board have reached the location of their surveys in the polar sea near the coast, what awaits them is weeks of hard work in the icy cold. For example, climate researchers extract metre-long sediment cores from the sea bed, which they hope will provide insight into how the climate has changed over the past 400,000 to 4 million years. And after a total of seven months at sea and more than 68,000 kilometres, when the ship enters its home port of Bremerhaven there is scarcely time for a break. The next expedition is waiting. This time their goal is the North Pole.
The Polarstern crosses the Arctic almost every year in the northern summer. And for ten years Michael Klages’ team has regularly travelled to this region: the Fram Strait west of Spitzbergen, the interface between the North Atlantic and the Arctic Ocean. This is where the marine biologists of the Alfred Wegener Institute keep their “house garden”, a deep sea area in which they search for sea inhabitants directly beneath the ice floes, at depths of between 1,000 and 5,500 metres. And just as Peter Wiebe and his crew cast their MOCNESS, the biologists in the “house garden” also cast their catching device. At 16 points in the sea, which the Polarstern travels to one after the other over a distance of 125 kilometres, they take samples of water and sediment on board, and find a diversity that exceeds all their expectations. Huge quantities of bacteria, nematodes and copepods work their way through the sediment. Marine isopods, shrimps, sea cucumbers, starfish and countless fish are scurrying around down there – several thousand species per square metre.////
