Scientists explore a seafloor area newly exposed by iceberg A-84; discover vibrant communities of ancient sponges and corals.
An international team of scientists have uncovered a thriving underwater ecosystem off the coast of Antarctica that had never before been accessible to humans.
The team, including researchers from the University of Cambridge, were working in the Bellingshausen Sea off the coast of Antarctica when a massive iceberg broke away from the George VI Ice Shelf in January of this year.
The team, on board Schmidt Ocean Institute's R/V Falkor (too), changed their plans and reached the newly exposed seafloor 12 days later, becoming the first to investigate the area.
Their expedition was the first detailed study of the geology, physical oceanography, and biology beneath such a large area once covered by a floating ice shelf. The A-84 iceberg was approximately 510 square kilometres (209 square miles) in size, and revealed an equivalent area of seafloor when it broke away from the ice shelf.
"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 from 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 meters.
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 lies 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 current expedition was the first to use an ROV to explore 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-meter-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, 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 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 Montelli of University College London (UCL). "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 data."
"We were thrilled by the opportunity to explore the newly exposed seafloor," said team member Dr Svetlana Radionovskaya from Cambridge's Department of Earth Sciences. "The research will provide key insights into ice sheet dynamics, oceanography and sub-ice shelf ecosystems. At a time when the West Antarctic Ice Sheet is melting at an alarming rate, understanding these dynamics and their impacts is crucial."
In addition to collecting biological and geological samples, the team used autonomous underwater vehicles called gliders to study the impacts of glacial meltwater on the region's physical and chemical properties. Preliminary data suggest high biological productivity and a strong meltwater flow from the George VI 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. 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."
Svetlana Radionovskaya is a Junior Research Fellow at Queens' College, Cambridge.
Adapted from a media release by the Schmidt Ocean Institute.
