After years of cracks and collapses, a terrible iceberg finally broke away from the brown ice shelf of Antarctica last month and began to head out to sea. Like a retractable skylight, the event gave us a brief look at a hitherto inaccessible seabed full of life.
For five decades, the ocean beneath this massive piece of ice – about twice the size of Chicago – has been kept in the shadows. Now the first rays of the sun penetrate deep, about 30 kilometers down (18 miles). A German research ship that happened to be nearby had a seat in the front row.
For several weeks, the icebreaker Polarstern he waited for the winds of force and the dangerous waves to die, so that he could bypass this monstrous iceberg. This week, the ship finally had a chance.
The great iceberg that broke up on the Antarctic ice shelf. (NASA Earth Observatory)
Despite being dressed in darkness for half a century, the seabed has proven to host a surprising diversity of life in its muddy landscape. Pulling a room platform under the ship with a long cable, the researchers found many filters and stationary species, including sponges, anemones, sea cucumbers, starfish, soft corals, mollusks, fish and squid.
(OFOBS-PS124 Team / Alfred Wegener Institute)
Above: A sponge almost 30 centimeters (almost 12 inches) in diameter fixed on a small stone on the seabed.
Many of the organisms were gathered around the stones, which would have fallen on glaciers in the ocean.
(OFOBS-PS124 Team / Alfred Wegener Institute)
Above: Numerous small sponges, bryozoans and corals encrust stones scattered on the seabed, with a worm leaving a spiral of feces between them.
The presence of filters is particularly interesting. Phytoplankton is what creatures of this kind usually filter from water to eat, but it is believed that these small organisms rely on sunlight; they are usually not found in the depths of the ocean.
(OFOBS-PS124 Team / Alfred Wegener Institute)
Above: A stone that supports many filters. White curls are the arms of a fragile star used to capture food and prey.
But maybe in the darkness of Antarctica, they are not as rare as I thought. Or maybe there are other microscopic organisms or nutrients that these fixed creatures filter in their place.
Just last month, scientists drilled 900 meters deep into the Antarctic ice shelf above the Western Weddell Sea, about 260 kilometers (162 miles) from the coast. However, even here, in this incredibly isolated slice of sea, the team was shocked to find sponges and other filters fixed to the stones.
“Our discovery raises so many questions that it answers,” said biogeographer Huw Griffiths of the British Antarctic Survey at the time, “how did they get there? What does it eat? How long have I been there? How common are these boulders covered with life? Are they the same species we see outside the ice shelf or are they new species? And what would happen to these communities if the ice shelf collapsed? ”
The team on board Polarstern has already shared numerous sediment samples from this newly unveiled seabed, as well as a once-in-a-lifetime photo album.
(OFOBS-PS124 Team / Alfred Wegener Institute)
Above: An anemone almost 30 centimeters in diameter next to the remains of a worm’s feces. Laser point for the ladder.
“We are extremely fortunate to have been able to respond flexibly and explore the Brunt ice shelf calving event in such detail,” says physical oceanographer Hartmut Hellmer of the Helmholtz Center for Polar and Marine Research at the Alfred Wegener Institute.
“That being said, I am even happier that I have successfully replaced a number of anchors, which will continue to record basic data on the temperature, salinity and directions and speed of the ocean current once I leave.”
(Ralph Timmermann / Alfred Wegener Institute)
On top Polarstern crossing the smallest gap between the iceberg and the Brunt Ice Rack, known as the “foxhole” because it is such a tight grip.
The data collected from this risky effort 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 priceless ecosystems before it is too late.
“We need this knowledge to be able to take effective action against climate change,” says Hellmer.
“The effects of climate change in Antarctica, among other things, are worrying.”