Thriving Antarctic ecosystems found in wake of recently detached iceberg
An international team on board Schmidt Ocean Institute’s research vessel Falkor (too) working in the Bellingshausen Sea rapidly pivoted their research plans to study an area that was covered by ice up until last month.
On January 13, 2025, an iceberg the size of Chicago, named A-84, broke away from the George VI Ice Shelf, one of the massive floating glaciers attached to the Antarctic Peninsula ice sheet. The team reached the newly exposed seafloor on January 25 and became the first to investigate an area that had never before been accessible to humans.
The expedition was the first detailed, comprehensive, and interdisciplinary study of the geology, physical oceanography, and biology beneath such a large area once covered by a floating ice shelf. The ice that calved was approximately 510 square kilometres, 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, 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 1300 metres.
Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus.
The discovery offers new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.
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.
The team was surprised by the significant biomass and biodiversity of the ecosystems and suspect they have discovered several new species.
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 hypothesises that currents are a possible mechanism for sustaining life beneath the ice sheet. The precise mechanism fueling these ecosystems is not yet understood.
The newly exposed Antarctic seafloor also allowed the international team, with scientists from Portugal, the United Kingdom, Chile, Germany, Norway, New Zealand, and the United States, 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.
In addition to collecting biological and geological samples, the science team deployed autonomous underwater vehicles called gliders to study the impacts of glacial meltwater on the physical and chemical properties of the region. Preliminary data suggest high biological productivity and a strong meltwater flow from the George IV ice shelf.
The expedition was part of Challenger 150, a global cooperative focused on deep-sea biological research and endorsed by the Intergovernmental Oceanographic Commission of UNESCO (IOC/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 scientific opportunity."
