When a giant iceberg the size of Chicago broke away from one of the massive floating glaciers making up the Antarctic Peninsula ice sheet in January this year, it exposed an expanse of seafloor never before observed by scientists.

Taking the opportunity to explore it, a team of researchers – an international team aboard the Schmidt Ocean Institute’s R/V Falkor (too) – changed their current course to find out just what the detached mass of ice could possibly have left in its wake.

What those researchers uncovered left them astonished. Because in its wake was left a “beautiful, thriving ecosystem” which – based on the size of the animals they found there – had likely “been there for decades… perhaps even centuries.”

As well as this, they found what is now suspected to be new species, too.

The team had originally been working in the Bellingshausen Sea but rapidly pivoted their research plans to study an area that had – until this January – been covered by ice. 

The expedition has now made history as the first detailed, comprehensive, and interdisciplinary study of the geology, physical oceanography, and the biology beneath such a large area once covered by a floating ice shelf.

The ice that calved was approximately 510 square-kilometres (around 209 square miles), revealing an equivalent area of seafloor.

“We seized upon the moment, changed our expedition plan, and went for it so we could look at what was happening in the depths below,” said expedition co-chief scientist, Dr Patricia Esquete of the Centre for Environmental and Marine Studies (CESAM) and the Department of Biology (DBio) at the University of Aveiro in Portugal.

“We didn’t expect to find such a beautiful, thriving ecosystem. Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Using Schmidt Ocean Institute’s remotely operated vehicle, ROV SuBastian, the team observed the deep seafloor for eight days and found flourishing ecosystems at depths as great as 1,300 metres. Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus.

This discovery now offers new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.

Relatively little is known about what dwells beneath Antarctica’s floating ice shelves. In 2021, British Antarctic Survey researchers first reported signs of bottom-dwelling life beneath the Filchner-Ronne ice shelf in the Southern Weddell Sea.

The expedition on Falkor (too) was the first to use an ROV to explore sweeping landscapes containing abundant life in this remote environment.

Deep-sea ecosystems typically rely on nutrients from the surface slowly raining down to the seafloor. However, these Antarctic ecosystems have been covered by 150-metre-thick ice for centuries, completely cut off from surface nutrients. 

Ocean currents also move nutrients, and the team hypothesizes that currents are a possible mechanism for sustaining life beneath the ice sheet. The precise mechanism fuelling these ecosystems is not yet understood.

The newly exposed Antarctic seafloor also allowed the team to gather critical data on the past behaviour of the larger Antarctic ice sheet. The ice sheet has been shrinking and losing mass over the last few decades due to climate change.

“The ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said expedition co-chief scientist Sasha Montellis of University College of London in the UK and a 2019 Schmidt Science fellow. “Our work is critical for providing longer-term context of these recent changes, improving our ability to make projections of future change – projections that can inform actionable policies.

“We will undoubtedly make new discoveries as we continue to analyse this vital data.”

The overall expedition was part of Challenger 150, a global cooperative focused on deep-sea biological research and endorsed by the Intergovernmental Oceanographic Commission of UNESCO as an Ocean Decade Action.

“The science team was originally in this remote region to study the seafloor and ecosystem at the interface between ice and sea,” said Schmidt Ocean Institute executive director, Dr Jyotika Virmani. “Being right there when this iceberg calved from the ice shelf presented a rare opportunity. 

“Serendipitous moments are part of the excitement of research at sea – they offer the chance to be the first to witness the untouched beauty of our world.”

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