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After years of cracking and crumbling, a huge iceberg finally broke off the Brunt Ice Shelf in Antarctica last month and began to drift out to sea. Like a retractable skylight, the event gave us a rare glimpse of a hitherto inaccessible seabed, absolutely teeming with life.
For five decades, the ocean beneath this huge chunk of ice – roughly twice the size of Chicago – has been kept in shadow. Now the first rays of the sun are penetrating a seabed about 30 kilometers (18 miles) below the pack ice. A nearby German research vessel had a front row seat.
For several weeks, the icebreaker Polarstern wait for the strong winds and dangerous waves to die out before he can get around this monstrous iceberg. This week, the ship finally had its chance.
The large iceberg that separated from the Antarctic pack ice. (NASA Earth Observatory)
Although plunged into obscurity for half a century, the seabed has proven to be home to a surprising diversity of life in its silty landscape. Towing a camera platform under the ship with a long cable, the researchers found numerous filter filters and stationary species, including sponges, anemones, sea cucumbers, starfish, soft corals, mollusks. , fish and squid.
(OFOBS-Team PS124 / Institut Alfred Wegener)
Above: A sponge about 30 centimeters (almost 12 inches) in diameter attached to a small rock on the seabed.
Many organisms were huddled around stones, which would have rushed down the glaciers into the ocean.
(OFOBS-Team PS124 / Institut Alfred Wegener)
Above: Numerous small sponges, bryozoa and corals encrust stones scattered on the seabed, with a worm leaving a spiral of excrement in between.
The presence of filters is particularly interesting. Phytoplankton is what creatures like this typically filter water to eat, but these tiny organisms are believed to depend on sunlight; they are generally not found in the depths of the ocean.
(OFOBS-Team PS124 / Alfred Wegener Institute)
Above: A stone supporting many filter feeders. White curls are the arms of a fragile star used to capture food and prey.
But maybe in the darkness of Antarctica they’re not as rare as we thought. Or maybe there are other microscopic organisms or nutrients that these fixed-place creatures are filtering out.
Last month, scientists drilled 900 meters (0.6 miles) deep in the Antarctic sea ice above the western Weddell Sea, about 260 kilometers (162 miles) from the coast. Yet even here in this incredibly secluded slice of sea, the team were shocked to find sponges and other filter filters also attached to stones.
“Our discovery raises so many more questions than it answers,” said biogeographer Huw Griffiths of the British Antarctic Survey at the time, “how did they get there? What are they eating? How long have they been there? These rocks covered with life? Are these the same species we see outside the pack ice or are they new species? And what would happen to these communities if the ice floes collapsed?
The team aboard the Polarstern has already shared numerous sediment samples from this newly revealed seabed, as well as an album of unique photographs.
(OFOBS-Team PS124 / Alfred Wegener Institute)
Above: An anemone nearly 30 centimeters in diameter next to the remains of a fecal trace of a worm. Laser point for the scale.
“It is extremely fortunate that we were able to respond flexibly and explore the calving event on the Brunt Ice Shelf in such detail,” says physical oceanographer Hartmut Hellmer of the Helmholtz Center for Polar and Marine Research. of the Alfred Wegener Institute.
“That being said, I am even happier that we have managed to replace a number of moorings, which will continue to record elementary data on temperature, salinity and ocean current directions and speeds once we get there. gone.”
(Ralph Timmermann / Alfred Wegener Institute)
Above Polarstern crossing the tiniest gap between the iceberg and the Brunt Ice Shelf, known as the “foxhole” because it’s such a tight squeeze.
The data collected as part of this risky endeavor will be used to better understand how the Antarctic ice sheet will respond to climate change in the future and what we can do to best protect these invaluable ecosystems before it’s too late.
“We need this knowledge to be able to take effective countermeasures against climate change,” says Hellmer.
“The effects of climate change in Antarctica, among others, are worrying.”
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