77 animal species discovered under the Antarctic ice shelf | Polarjournal
On the seafloor beneath the ice shelf in the Antarctic Atka Bay, researchers from the Alfred Wegener Institute and the British Antarctic Survey found an unexpectedly large diversity of living organisms. Photo: Alfred Wegener Institute

There is more marine life under the Antarctic ice shelf than expected. This is shown by a recent study of the British Antarctic Survey together with the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. During their research, the team discovered the large number of 77 species of animals that populate the seafloor beneath an ice shelf. The researchers have now published their results in the scientific journal Current Biology.

Using hot water, a team of researchers from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research, Germany, drilled two holes, through nearly 200 metres of the Ekström Ice Shelf near Neumayer Station III in the South Eastern Weddell Sea in 2018. The fragments of life on the seabed collected were extra-ordinary and completely unexpected. Despite being several kilometres from the open sea, the biodiversity of the specimens they collected was extremely rich. The team discovered 77 species – including saber-shaped bryozoans (bryozoans) like Melicerita obliqua and serpulid worms like Paralaeospira sicula – more than were previously known from this entire environment. This means that the species diversity is even greater than in many open-water samples found on the continental shelf of Antarctica, where there is light and sufficient food sources compared to the sea floor.

A: Study area on the eastern edge of the Weddell Sea. B: Drilling sites on the Ekström Ice Shelf in Atka Bay. Illustrations: Barnes et al. 2021

“This discovery of so much life living in these extreme conditions is a complete surprise and reminds us how Antarctic marine life is so unique and special. It’s amazing that we found evidence of so many animal types, most feed on micro-algae (phytoplankton) yet no plants or algae can live in this environment. So the big question is how do these animals survive and flourish here?” Lead author Dr David Barnes, a marine biologist at British Antarctic Survey, says.

The team concludes there must be enough algae carried under the ice shelf from open water to fuel a strong food web. Microscopy of samples showed that, surprisingly, annual growth of four of the species was comparable with similar animals in open marine Antarctic shelf habitats.

“Another surprise was to find out how long life has existed here. Carbon dating of dead fragments of these seafloor animals varied from current to 5800 years. So, despite living 3-9 km from the nearest open water, an oasis of life may have existed continuously for nearly 6000 years under the ice shelf. Only samples from the sea floor beneath the floating ice shelf will tell us stories from its past history,” says co-author Dr Gerhard Kuhn (AWI), who coordinated the drilling project.

Left: Fragments of bryozoan (bryozoan) colonies that the researchers found on the seafloor. Photo: David Barnes. Right: Researchers from the Alfred Wegener Institute used hot water to drill through the ice shelf to the sea floor. Photo: Sophie Berger

Current theories on what life could survive under ice shelves suggest that all life becomes less abundant as you move further away from open water and sunlight. Past studies have found some small mobile scavengers and predators, such as fish, worms, jellyfish or krill, in these habitats. But filter feeding organisms–which depend on a supply of food from above–were expected to be amongst the first to disappear further under the ice. The team also notes that with climate change and the collapse of these ice shelves, time is running out to study and protect these ecosystems.

Press release Alfred Wegener Institute

Link to the study: David K.A. Barnes, Gerhard Kuhn, Claus-Dieter Hillenbrand, Raphael Gromig, Nikola Koglin, Boris K. Biskaborn, Bettina A.V. Frinault, Johann P. Klages, Julian Gutt: Richness, growth, and persistence of life under an Antarctic ice shelf . Current Biology, Dec. 20, 2021, DOI: 10.1016/j.cub.2021.11.015

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