Scientists thought this Antarctic sea floor would be barren. But it’s teeming with life

When the crew aboard an ocean science expedition learned that an iceberg the size of Chicago had broken off from an Antarctic ice shelf, they knew they had to stop what they were doing immediately and go check it out. 

After all, it provided a unique opportunity to explore the sea floor in an area of the ocean previously cut off to humans.

Despite their excitement, the team on the Schmidt Ocean Institute vessel didn’t think they would find much life so far beneath the ice, far beyond the reach of the sun.

Turns out, they were dead wrong.

The first image that came through to the ship’s control room from the team’s remotely operated vehicle revealed a large sea sponge with a crab crawling on it, says Patricia Esquete, the expedition’s chief scientist at the time of the discovery.

“It was a lot of excitement,” she told As It Happens host Nil Köksal. “Then, hour by hour and day by day, we kept seeing more.”

Esquete and her colleagues have documented a surprisingly lush and diverse marine ecosystem that includes corals, sponges, fish, giant sea spiders, octopuses and more, some of which are likely new to science. 

But it remains a mystery as to how so much life could have flourished in the dark ocean depths, some 1,300 metres beneath the George VI Ice Shelf, one of the massive floating glaciers attached to the Antarctic Peninsula ice sheet.

It’s also not clear what will happen to this ecosystem now that’s been fundamentally altered by the loss of that ice. 

“It is a very interesting discovery and I can’t wait to see all the new species discovered and to understand what maintains biodiversity in these ecosystems,” said Guadalupe Bribiesca-Contreras, an applied scientist at England’s National Oceanography Centre, who wasn’t involved in the expedition. 

Esquete, a deepsea ecologist and taxonomist from Portugal’s University of Aveiro, says the crew had been exploring the ocean floors of the Bellingshausen Sea along the west side of the Antarctic Peninsula in January when they saw, via satellite imagery, that a new iceberg was breaking off from George VI.

“We immediately we knew we had to go there and explore that particular area,” she said. “Our expectations were a very impoverished ecosystem because, you know, normally a marine ecosystem is fed by the energy of the sun.”

That’s true even in the deepest depths, as nutrients from photosynthesizing organisms slowly rain down to sustain ecosystems below.

But for centuries, this region was covered with nice nearly 150 metres thick. Before that, the ice was so thick it touched the ocean floor. 

“That means that photosynthesis cannot happen … and food is not going to be produced,” Esquete said. “So we were expecting some forms of life fed by food that is being transported laterally by the currents, but we didn’t expect much.”

If food and energy is not raining down from above, what’s been powering and feeding this region that’s teeming with life? 

“That’s going to be really the most exciting research that we can do,” Esquete said.

The team collected imagery, as well as some specimens and geological samples. Scientists will look at the geology of the region, as well as ocean currents, to try to puzzle out “how the whole system works,” she said. 

But the first step, Esquete says, will be to classify all the creatures they observed.

“So a full morphological study of all the species that we found, and then genetic analysis,” she said. 

She suspects dozens of them could be new to science. 

“We were in an area that’s been very little explored. And we know that when you explore the deep sea, when you sample the deep sea, you always find new species.”

While the iceberg calving when and where it did was serendipitous for the crew, it didn’t come out of nowhere. The ice sheet has been melting and shrinking for decades due to climate change.

University of Victoria marine biologist Verena Tunnicliffe, who was not involved in the expedition, wonders how this newly discovered ecosystem will change now that it’s been exposed. 

“They took a very unusual opportunity to explore a world that has been hidden under extremely thick ice for thousands of years,” said Tunnicliffe, a Canada research chair in deep ocean research. 

“This expedition is able to create a set of ‘baseline’ data: the original habitat and ecosystem. And how will it change now the curtain is pulled back? Hopefully, it will remain accessible in coming years to measure the changes, thereby understanding the unique conditions below the thick ice.”

Esquete, meanwhile, is excited to unravel some marine mysteries. 

“What makes possible that array of life is something that we really want to figure out,” she said.