Life touches wherever it can, even under thick ice cover in Antarctica.
German scientists inspected an area with seabed recently exposed by the calving of the mega-iceberg A74, and found that it was teeming with animals.
Camcorders have continuous filter feeders that thrive among the soft mud.
It was a remarkable opportunity for the team as their ship, RV Polarstern, bridged the still-narrow gap between the A74 and the Brunt ice shelf, which yielded the giant mountain.
Research groups regularly try to investigate waters under freshly calved ice shelves, to better understand how these unique ecosystems work. But success is not easily won.
You need to be in the right place in Antarctica at the right time, and often the ice conditions simply will not allow a research ship to position above the target area.
But Polarstern, run by the Alfred Wegener Institute, was lucky. It was already in the eastern Weddellsee on a pre-planned expedition when the town A74 split off from the Brunt.
And when the weather calmed down this past weekend, the ship slipped behind the mountain to view a portion of the seabed that is now, for the first time in five decades, free of ice cover.
Polarstern has an ocean floor observation and bathmetry system (OFOBS). It is a sophisticated instrument package that is towed at depth behind the ship.
The system collected nearly 1,000 high-resolution images and long video series over five hours.
“Despite the years of continuous ice cover, a developed and diverse seabed community has been observed,” said OFOBS team members Dr Autun Purser and Dr Frank Wenzhoefer.
“In the images, numerous sedentary animals can be seen attached to various small stones that are spread over the soft seabed.
“Most of these are filter-fed organisms and probably consist of fine material that has been transported under the ice during the last decades.
“Some mobile fauna, such as holothurians, ophiuroids, various mollusks, as well as at least five species of fish and two species of octopuses have also been observed.”
Dr Huw Griffiths of the British Antarctic Survey was delighted with the photos returned from the Polarstern.
“What they found is not shocking, but it is surprising to get these images so soon after a calving event, and it is certainly the largest area that will be explored in this way,” he said.
‘Finding these types of communities so far below the ice shelf is not surprising, but it is a good indication that there is a rich supply of food that reaches at least 30 km below the ice shelf.
“This food is produced by plankton in the sunny sea surface nearby, and then dragged under the ice shelf by the currents of Lake Weddell. The same currents will eventually move the iceberg westward around Lake Weddell and then northward to its collapse,” he said. he said. told BBC News.
From a research perspective, the idea would be to go back at regular intervals to document any changes to the ecosystem.
This is something Polarstern can do because AWI is doing long-term studies in the region.
The eastern side of the Weddell Sea is interesting because it has not seen the warming effects observed in the western sector along the Antarctic Peninsula.
However, this situation may not be expensive, but computer models suggest that by the end of the century, regular inflows of warm ocean water from the north may occur.
Where is it in Antarctica?
A74 breaks away from the Brunt Ice Shelf, which is the floating protrusion of glaciers that flowed from the land into the Weddell Sea. On a map, Lake Weddell is the part of Antarctica directly south of the Atlantic Ocean. The Brunt is on the east side of the sea. Like all ice racks, it will calve icebergs regularly. A large mountain last calved from this particular area in 1971.
How big is the iceberg A74?
Satellite measurement is approximately 1,290 square kilometers. Greater London is about 1,500 sq km; the Welsh county of Monmouthshire is about 1,300 sq km. It is large anyway, though not as large as the sample A68 mountain that calved in July 2017 from the Larsen C ice shelf on the west side of Lake Weddell. It was originally about 5,800 square miles, but has since shattered into very small pieces.
