Iceberg break from Antarctica reveals seafloor full of rare and vibrant ocean creatures

An international team of researchers took advantage of a rare chance encounter to explore a massive new expanse of seafloor exposed by the breakup of an Antarctic ice shelf in the Bellingshausen Sea. 

On January 13, 2025, an iceberg named A-84 – which was the size of the city of Chicago – broke off from the George VI Ice Shelf, which sits along the Antarctic Peninsula.

This event uncovered roughly 209 square miles (540 square kilometers) of seafloor that had previously been concealed under floating ice.

The team arrived aboard Schmidt Ocean Institute’s R/V Falkor (too) at this newly exposed site on January 25, making them the first to study such a large underwater area that had previously been covered by an ice shelf. 

Their effort marks the first large-scale interdisciplinary exploration of geologic, oceanographic, and biological features hidden beneath an extensive floating glacier front.

Rapidly shifting expedition goals

Co-chief scientist Patricia Esquete is a researcher in the Center for Environmental and Marine Studies (CESAM) and the Department of Biology (DBio) at the University of Aveiro in Portugal. 

“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 Esquete.

“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.”

Originally, the science mission did not include venturing beneath a freshly fractured portion of the ice shelf.

However, the movement of this newly calved iceberg offered a rare opportunity to explore a site that, until recently, had never been examined by any human.

Antarctic seafloor reveals lush communities

Using Schmidt Ocean Institute’s remotely operated vehicle, ROV SuBastian, the science team spent eight days surveying the seafloor at depths down to 1,300 meters (4,265 feet). 

The experts discovered an unexpectedly rich ecosystem that was teeming with corals, sponges, icefish, giant sea spiders, and octopuses – an indication that marine life can flourish under ice-covered regions of the Antarctic in ways not previously documented.

According to the researchers, these observations offer insight into how ecosystems function beneath the Antarctic ice sheet. Such an ecosystem has seldom been accessed.

Earlier findings, notably by British Antarctic Survey researchers in 2021, revealed possible bottom-dwelling life beneath ice, but the present study marks the first time an ROV survey has thoroughly documented wide areas of this vibrant seabed.

The experts were surprised by the large biomass and biodiversity in the ecosystem and suspect they have discovered several new species.

How marine life survives in darkness

Deep-sea ecosystems generally depend on nutrients trickling down from surface waters. However, these Antarctic seafloors had been buried under ice some 150 meters (nearly 500 feet) thick for centuries. 

With no direct sunlight, how such abundant organisms manage to feed is still uncertain. The scientists propose that ocean currents under the ice may be funneling essential nutrients to these communities.

Antarctic ice sheet behavior

Apart from their ecological discoveries, the international group – which included scientists from Portugal, the United Kingdom, Chile, Germany, Norway, New Zealand, and the United States – examined geological samples to gain knowledge about past changes in the Antarctic ice sheet.

The ice sheet has been shrinking and losing mass for decades in response to climate change. 

“The ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said co-chief scientist Sasha Montelli of University College London, who is also 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 analyze this vital data.”

Samples from the Antarctic seafloor

During this mission, the team collected both biological and geological samples.

In addition, they deployed autonomous underwater vehicles, called gliders, to analyze how meltwater from the ice shelf impacts the region’s physical and chemical properties. 

Preliminary measurements hinted at high biological productivity and strong meltwater flow from the George VI ice shelf, providing further context for how such deep-sea populations may thrive in these surroundings.

Part of a larger global initiative

The expedition is part of Challenger 150, a global cooperative dedicated to deep-sea biological study, and recognized by the Intergovernmental Oceanographic Commission of UNESCO (IOC/UNESCO) as an Ocean Decade Action. 

This alignment ensures that findings from the George VI Ice Shelf breakage feed into broader international efforts to understand and safeguard marine life.

“The science team was originally in this remote region to study the seafloor and ecosystem at the interface between ice and sea,” noted Schmidt Ocean Institute’s executive director, Jyotika Virmani. 

“Being right there when this iceberg calved from the ice shelf presented a rare scientific 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.”

Looking ahead, the researchers plan to continue analyzing the collected data for insights into both ice sheet behavior and the unique marine life that has flourished unseen for centuries beneath the ice. 

With accelerating climate change, the study’s findings about species adaptability and the resilience of Antarctic habitats carry implications for future conservation and policy decisions on a global scale.

See more of the photos taken on this mission by the Schmidt Ocean Institute here…

Images Credit: Schmidt Ocean Institute

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