A wide diversity of marine life, that may include previously unknown species, flourishes in a region of ocean once hidden beneath a thick cover of ice, finds a recently-returned Antarctic expedition
The expedition, in partnership with Schmidt Ocean Institute, examined and mapped the unseen submarine environment off the Antarctic Peninsula, in an area that was until recently covered by a massive ice shelf and that in late 2024 shed a colossal iceberg from its floating edge.
Using underwater remotely operated vehicles (ROVs), sonar soundings, sediment coring, water sampling and other techniques, the team spent ten days charting and characterising the underwater environment to an unprecedented level of detail. They collected data about the region’s current environment as well as evidence of past ice conditions.
Co-leader of the expedition, Dr Aleksandr Montelli (UCL Geography) said: “Ice shelves are among the most hostile and most remote environments on the planet and they’re extremely difficult to get underneath. To my knowledge, this is the first time a comprehensive and interdisciplinary study like this was completed in a sub-ice shelf environment, for ten days in a row with ROV dives, to see underwater ecosystems and seafloor communities in such levels of detail. It’s quite unprecedented.”
The researchers had originally planned to stay farther out in Bellingshausen Sea to study other ice-shelf systems and how they had changed over time. But when a massive iceberg about the size of Chicago broke away from Antarctica’s George VI ice shelf and floated out into the Bellingshausen Sea in December 2024, the researchers saw a rare opportunity to explore an otherwise inaccessible environment. They diverted their research vessel, the Schmidt Ocean Institute’s R/V Falkor (too), to the ice’s edge to peek under the remaining ice shelf and study the previously obscured ecosystem below.
Dr Montelli said: “When this large iceberg calved right as we were working next door, it presented an enticing opportunity because you cannot predict this calving and subsequent drifting with accuracy. We were immensely fortunate to be able to sample and produce a comprehensive, interdisciplinary analysis of the environments that exist underneath an ice shelf.”
Using the institute’s ROV SuBastian to reach the newly exposed seafloor, the team found a wide abundance of life below the shelf, including sponges, icefish, giant seaspiders, octopus and large, slow-growing cup corals, some of which may be newly discovered to science.
Co-chief scientist Dr Patricia Esquete of the University of Aveiro, Portugal, said: “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.”
In addition, the data gathered from the seafloor will help the researchers better understand the past and future of the ice shelf as Earth’s climate changes. Past growth and decay of Antarctica’s ice is recorded in the shape and structure of the seabed underneath. The expedition collected dozens of sediment cores, numerous seafloor samples and vast maps of the region which will take a few years to fully analyse.
Dr Montelli said: “Our work is critical for providing longer-term context of the recent changes we are seeing now, improving our ability to make projections of future change — projections that are actionable policy-making-wise. We will undoubtedly make new discoveries as we continue to analyse this vital data.”
In addition, researchers from the University of Cambridge, University of East Anglia and British Antarctic Survey on the cruise deployed autonomous underwater vehicles known as sea gliders to study the impact that water from melting glaciers is having on the region.
The researchers sailed as part of the most recent expedition by Schmidt Ocean Institute, a private non-profit research foundation to advance oceanographic research, discovery, and knowledge, and catalyse sharing of information about the oceans.
Dr Jyotika Virmani, Executive Director of Schmidt Ocean Institute, said: “What a serendipitous moment for these scientists to be able to go where no one has been before. Schmidt Ocean Institute is proud to support groundbreaking scientific research like this that provides critical information about our changing climate.”
