After years of cracks and crumbling, a huge iceberg finally came off the Antarctic ice shelf last month and began drifting into the sea. Like a retractable skylight, the event gave us a rare glimpse of a seabed that until now could not be reached, full of life.
For five decades, the ocean beneath this mass of ice, about twice the size of Chicago, has remained in the shade. Now, the first rays of sunlight penetrate to the depths, about 30 kilometers down (18 miles). A nearby German research ship had a seat in the front row.
For several weeks, the icebreaker Polarstern he has been waiting for strong winds and dangerous waves to move around this monstrous iceberg. This week, the boat finally had its chance.
The great iceberg that separated from the Antarctic ice shelf. (NASA Earth Observatory)
Despite being shrouded in darkness for half a century, the seabed turned out to be home to an astonishing diversity of life in its silty landscape. Throwing a camera 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-Team PS124 / Alfred Wegener Institute)
On top: A sponge almost 30 centimeters in diameter attached to a small stone on the seabed.
Many of the organisms were piled up around stones, which would have fallen down the glaciers into the ocean.
(OFOBS-Team PS124 / Alfred Wegener Institute)
On top: Numerous small sponges, bryozoans, and corals embed stones scattered across the seabed, with a worm leaving a spiral of feces in the middle.
The presence of filters is particularly interesting. Phytoplankton is what creatures like this usually filter from water to eat, but it is believed that these small organisms depend on sunlight; they are not usually found in the depths of the ocean.
(OFOBS-Team PS124 / Alfred Wegener Institute)
On top: A stone that supports numerous filters. White curls are the arms of a fragile star that is used to capture food and prey.
But perhaps in the darkness of Antarctica they are not as scarce as we thought. Or maybe there are other microscopic organisms or nutrients that these creatures fixed in place are leaking.
Just last month, scientists drilled 900 meters (0.6 miles) deep on the Antarctic ice shelf over the western Weddell Sea, about 260 kilometers (162 miles) from the coast. Yet, even here, in this incredibly isolated slice of sea, the team was surprised to find sponges and other filters also attached to the stones.
“Our discovery raises so many more questions than it answers,” said British Antarctic Survey biogeographer Huw Griffiths at the time, “such as how did they get there? What do they eat? How long have they been there? These covered stones “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 the Polarstern has already shared numerous sediment samples from this newly revealed seabed, as well as an album of photographs that cannot be passed on to life.
(OFOBS-Team PS124 / Alfred Wegener Institute)
On top: An anemone nearly 30 inches in diameter next to the remains of a worm’s fecal trail. Laser point for scale.
“We are very fortunate to be able to respond flexibly and explore the birth event on the Brunt ice shelf in such detail,” says physical oceanographer Hartmut Hellmer at the Helmholtz Center for Polar and Marine Research at the Alfred Institute. Wegener.
“That said, I’m even happier that we’ve successfully replaced some moorings, which will continue to record elementary data on temperature, salinity, and ocean current directions and speeds once we leave.”
(Ralph Timmermann / Alfred Wegener Institute)
Above: the Polarstern crossing the smallest gap between the iceberg and the Brunt ice shelf, known as the “fox hole” because it’s such a tight pressure.
The data collected from this risky effort will be used to better understand how the Antarctic ice sheet will respond to climate change and what we can do to better protect these invaluable ecosystems before it is too late.
“We need this knowledge to be able to take effective countermeasures against climate change,” Hellmer argues.
“The effects of climate change in Antarctica, among others, are worrying.”