Abundance of life found in darkness beneath Antarctic ice shelf

Scientists were sure that deep under the ice of Antarctica’s Ekström Ice Shelf, there was nothing but total darkness. Well, total darkness and a thriving ecosystem get along just fine, according to a new report from researchers in the UK and Germany.

“The discovery of so much life in these extreme environments is a complete surprise and reminds us how unique and special the Antarctic marine ecosystem is,” says lead author and British Antarctic Survey marine biologist David Barnes.

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“It’s amazing that we found evidence for the existence of so many animal species, most of which feed on microalgae (phytoplankton), but no plants or algae can live in this environment. So the big question is how do these animals survive and thrive here?”

Researchers used hot water to drill two wells on the relatively small Ekström Ice Shelf in East Antarctica back in 2018. One well went 192 meters of ice until it reached 58 meters of liquid water. while the other covered 190 meters of ice and 110 meters of water underneath.

In this dark, cold and scarce place under the ice, they found life in very large quantities. The team found 77 species of bryozoans, including the saber-like Melicerita obliqua and serpulids such as Paralaeospira sicula.

All of these creatures are suspension feeders — they sit in one place and with the help of feathery tentacles snatch particles of organic matter from the water as it flows around them — this means that some source of food must get into it, for example, algae dependent on the sun. Sveta.

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This is quite surprising, given that the nearest open source of water is 9.6 km away. And past research has shown life even further inland, on larger ice sheets like the Ross and McMurdo ice shelves.

Despite constant darkness for at least thousands of years, life has been observed even as far as 700 km from the edges of the ice shelf. It was believed that the wealth and abundance of life under the ice shelves is extremely poor. However, biodiversity at both well sites will be high even for open sea samples from the Antarctic continental shelf.

But researchers didn’t just find modern filter feeders deep under the ice. They also looked at long-dead fragments and carbon-dated them to determine their age.

“Another surprise was to find out how long life has been here. Carbon dating of the dead fragments of these marine animals ranged from today to 5,800 years,” says Gerhard Kuhn, geologist at the Alfred Wegener Institute for Polar and Marine Research.

“Thus, despite the fact that we were working 3-9 km from the nearest open water, an oasis of life may have existed continuously for almost 6,000 years under the ice shelf. Only samples from the bottom of the sea beneath the floating ice shelf will tell us stories from its past.»

This raises another issue — during the glacial events of the past, when most of the Antarctic shelf was covered by ground ice (ice that reaches the bottom of the sea), how did these dark ecosystems survive?

New information suggests that these creatures lived in small areas that were not grounded, while open areas of water surrounded by sea ice could allow phytoplankton to flourish and then be eaten by these creatures far below the ice. The plankton would have been swept under the ice by the current, within reach of the hungry creatures far below.

Unfortunately, despite the incredibly long life of these ecosystems so far, researchers are worried about their future.

“Most places may be cold, dark and food scarce,” the team writes, “but the least disturbed habitat on Earth could be the first habitat to die out as conditions under the ice shelf disappear due to global warming.”

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