Iceberg detachment in Antarctica reveals a fascinating underwater ecosystem

What lies beneath an ice shelf? Scientists aboard the research vessel R/V Falkor, operated by the Schmidt Ocean Institute, have just shed light on this mystery. They took advantage of a rare opportunity to explore the seafloor after a massive iceberg broke off from the Antarctic Peninsula’s ice shelf, uncovering hundreds of marine creatures.

A remarkable deep-sea discovery

There are few places left on Earth untouched by human exploration. On January 13, 2025, when iceberg A-84, with a surface area of about 510 km², calved from the George VI Ice Shelf, an international team of researchers operating in the Bellingshausen Sea quickly changed their plans to explore the previously inaccessible seafloor. The results exceeded their wildest expectations.

Dr. Patricia Esquete from the Centre for Environmental and Marine Studies (CESAM), who led the research, admitted that no one anticipated discovering such a beautiful and thriving ecosystem. At a depth of 1,300 meters below sea level, the team identified vast colonies of corals and sea sponges providing shelter for many species, including icefish, octopuses, and giant sea spiders known as pycnogonids. Based on the size of these organisms, researchers suggested that the discovered populations may be several hundred years old.

How is life possible under the ice cover?

The presence of rich ecosystems beneath ice shelves has been suggested by earlier studies – in 2021, a British team drilling through the Filchner-Ronne Ice Shelf in the Weddell Sea discovered a surprising abundance of fauna, including sea urchins, polychaetes, sea cucumbers, and gastropods. The current research marks a breakthrough, as it is the first time that the remotely operated underwater vehicle SuBastian was used to explore the seafloor for eight days, providing detailed images and samples. Among the discovered organisms, scientists noticed life forms that may be new species, opening the door to further analysis and underscoring the uniqueness of this ecosystem.

But how is life possible under an ice layer up to 150 meters thick that blocks light and nutrients? Scientists aboard the R/V Falkor point to the key role of ocean currents, which transport nutrients horizontally, often across vast distances beyond the edge of the ice and sea. This discovery is particularly significant given that ice shelves cover about one-third of Antarctica’s 5 million km² continental shelf, potentially hiding immense biological wealth.

The calving of iceberg A-84 raises further questions

Scientists are intrigued not only by what is happening in the depths. The detachment of iceberg A-84 is part of the natural calving process of glaciers, which continuously reduces the volume of the Antarctic ice sheet and raises global sea levels. In addition to seafloor exploration, the team aboard the R/V Falkor analyzed the effects of meltwater on the region’s physical and chemical conditions. Preliminary data indicate that the George VI Ice Shelf is shrinking rapidly, and the released water is characterized by high biological productivity.

Meanwhile, NASA has been tracking iceberg A-84 since mid-January. It is moving at a surprisingly fast pace, covering 250 km in just one month thanks to coastal Antarctic currents. This raises new questions about what processes are currently taking place beneath the ice shelves.

Climate change and the future of glaciers

Glacial calving is a natural phenomenon, but its intensity has significantly increased in recent decades due to climate change. Rising air and ocean temperatures, combined with the consistent loss of sea ice – which serves a protective role – may lead to the complete disintegration of more ice shelves. Notably, in 2002, the 3,250 km² Larsen B Ice Shelf collapsed within just one month. Then, in January 2023, iceberg A-81, with an area of over 1,550 km², calved from the Brunt Ice Shelf. In May 2024, iceberg A-83, measuring 375 km², broke off from the same ice shelf, further destabilizing the Antarctic coastline. What will happen next?

main photo: ROV SuBastian / Schmidt Ocean Institute