Thriving Antarctic ecosystems found in wake of recently detached iceberg
By: Communications
An international team of scientists has discovered vibrant communities of ancient sponges and corals after an iceberg calving in Antarctica.
On January 13 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 on board Schmidt Ocean Institute’s R/V Falkor (too), which included Dr Meredith Meyer from the University of East Anglia, was working in the Bellingshausen Sea. The researchers rapidly changed their plans and reached the newly exposed seafloor on January 25, becoming 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 (209 square miles), revealing an equivalent area of seafloor and offering new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.
Seizing the moment
"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 meters.
Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus.
Dr Meredith Meyer and colleagues prepare to deploy a glider in the Bellingshausen Sea. Photo: Aleksandr Montelli/UCL
In addition to collecting biological and geological samples, the 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 suggests high biological productivity and a strong meltwater flow from the George VI ice shelf.
This work, part of an Advanced Research and Innovation Agency (ARIA) funded project between UEA, the University of Cambridge and British Antarctic Survey (BAS), saw two gliders equipped with physical and biogeochemical sensors deployed to survey the Bellingshausen region for approximately two weeks.
While Dr Meyer was on board Falkor (too), she was supported on land by principal investigator for UEA Prof Karen Heywood and colleagues from the UEA Glider Group.
“Our plans pretty much completely changed when the iceberg broke away from the George VI Ice Shelf,” said Dr Meyer. “It allowed us to additionally assess the impact of this calving event on the meltwater transport, water mass interactions, and overall oceanography of the region. We were able to keep the gliders in the water approximately three times longer than expected, which has produced a huge amount of important data.”
Two floats equipped with ice-avoidance technology were also deployed and will remain in the region to collect physical oceanographic data over multiple years.
“Like much of Western Antarctica, the Bellingshausen Sea has been experiencing substantial warming and ice loss in recent years as a result of climate change,” explained Dr Meyer. “However, the remoteness and logistical difficulty in getting to the region has prevented scientists from getting a comprehensive and quantitative understanding of these changes.
“Plans always change a bit on an expedition, but this was an extreme change with a whole area opening up for the first time. It was an amazing experience and really valuable to be able to take advantage of the opportunity to explore it, everyone on board was really willing to do something new.”
New ecosystems revealed
Little is known about what dwells beneath Antarctica’s floating ice shelves. In 2021, BAS 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-meter-thick (almost 500 feet) 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 international team, with scientists from Portugal, the UK, Chile, Germany, Norway, New Zealand, and the US, 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), 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.”
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.”
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