MBARI leads international expedition to study impacts of climate change on Antarctic seafloor

MBARI scientists recently returned home from a seven-day expedition where they conducted the first controlled-source electromagnetic survey in Antarctic waters. Funded by the Polar Research Infrastructure Network (POLARIN), the FLAIR expedition—fluid-seafloor interactions across the Antarctic seafloor under climate-driven change—was carried out in collaboration with GEOMAR Helmholtz Centre for Ocean Research Kiel, Stockholm University, The University Centre in Svalbard, the University of Barcelona, the University of Haifa, and the University of Milano-Bicocca.

The goal of the expedition was to explore how fluid flow systems under the seafloor are impacted by a rapidly warming polar environment. Working aboard the Spanish polar research vessel Hespérides, the team focused on the Bransfield Basin in the northern Western Antarctic Peninsula, a region that is experiencing some of the fastest warming in the Southern Hemisphere.

“Beneath Antarctica’s seafloor, groundwater and gas move through what is essentially an underground plumbing system. As these fluids move around, they may sculpt the seafloor and sub-seafloor, creating conditions that can support various kinds of marine life,” said MBARI Senior Scientist Aaron Micallef, who led the expedition. “These systems are incredibly important, but their processes remain poorly understood in much of the Southern Ocean.”

The research team conducted high-resolution mapping of the seafloor, sub-seafloor, and water column, collected water and sediment samples, deployed a marine controlled-source electromagnetic (CSEM) system, and surveyed seafloor communities with a remotely operated vehicle (ROV). These tools provided a comprehensive picture of seafloor geology and ecosystems to help researchers better understand how fluids move through the Antarctic seafloor and how past ice dynamics and ongoing climate change may influence that movement.

“It will take months to fully interpret what we mapped and sampled here, but it is already clear that these seafloor systems hold critical clues about marine hydrogeology, deep-sea ecosystems, and the stability of Antarctic seafloor in a warming world,” said Micallef.

The expedition faced many challenges due to the cold, unstable weather found in the Antarctic, but was able to conduct research in three locations: Deception Island, King George Island, and the Astrolabe Trough.

Deception Island: Severe weather leads to an unplanned, but valuable, stop

During the first few days of the expedition, the team faced severe weather in Bransfield Strait, forcing them to adapt their schedule and conduct research at Deception Island, an active volcanic caldera.

The scientists used a multibeam echosounder on the ship to detect several upward-rising streams of bubbles escaping from the seafloor into the water. They also conducted a series of ROV dives which found the seafloor to be full of sponges and sea squirts thriving in conditions shaped by volcanic activity.

“Sometimes the most interesting science happens when plans change,” said Micallef. “This is a very different system from the methane- and groundwater-dominated environments we were targeting, but it is a powerful reminder that heat and volcanism can be key drivers of healthy seafloor ecosystems.”

King George Island: Connecting marine life and seafloor processes

The second stop on the expedition was King George Island, where the team deployed a CSEM system. On loan from the University of Malta and upgraded by MBARI engineers, the CSEM system collects information about the electrical properties below the seafloor to detect ice, brackish water, and gas buried in submarine sediments. This technology can identify fluid pathways beneath the seafloor along a 40-kilometer (25-mile) path, helping researchers survey seafloor processes over long distances. The goal was to understand how those fluids behave, move, and are stored within the rocks and sediment on the seafloor.

The team collected sediment samples using a gravity corer deployed from R/V Hespérides. From these samples, they extracted porewater—water between sediment particles—for chemical analysis. The presence of methane and freshened groundwater will help researchers determine if the degradation of underwater permafrost or changes in terrestrial groundwater systems onshore are occurring. They also used the ROV to collect water and gas samples and document the biological community living on the seafloor.

“I’m looking forward to analyzing all the different data collected at this site, but we can already see the strong connection between the processes happening below the seafloor and Antarctic marine life,” said Micallef.

Astrolabe Trough: Navigating icebergs for high scientific payoff

The expedition’s final stop was the little-studied Astrolabe Trough and the adjacent continental shelf along the Western Antarctic Peninsula. The few studies that have been conducted in this region reported the presence of “mega pockmarks,” large depressions on the seafloor.

The research team deployed the CSEM system in this area as well, looking to map underground fluids and reconstruct how the repeated advance and retreat of glacier ice sheets have shaped the seafloor.

“It was exciting—and challenging—to use this technology for the first time in Antarctic waters. To conduct the survey, our team had to manage the long geophysical lines behind the boat while continuously navigating around icebergs. It’s the combination of challenging logistics and high scientific payoff that makes this region so compelling,” said Micallef.

Next steps

The FLAIR expedition collected the first integrated geophysical, geochemical, and biological dataset for the seafloor adjacent to the Western Antarctic Peninsula. MBARI researchers and their collaborators will now begin to analyze this trove of data to gain new insights into the role of subsurface fluids in shaping the Antarctic continental margin. Their findings will help establish a critical baseline for assessing how continued climate warming may influence hydrogeology, sediment stability, and benthic habitats in polar shelf environments.

From the Arctic to the Southern Ocean, MBARI research and technology are helping answer fundamental questions about polar environments. This information can help resource managers and policymakers make decisions about the future of these important ecosystems.

The FLAIR Expedition was made possible by POLARIN (Grant Agreement ID: 101130949), funded by the European Union’s Horizon Europe programme, with additional support from UTM-CSIC, King Sejong Station, and QPS. Additional funding for this research came from the David and Lucile Packard Foundation, as part of its longstanding support for MBARI’s work to advance marine science and engineering to understand our changing ocean.

About MBARI

MBARI (Monterey Bay Aquarium Research Institute) is a non-profit oceanographic research center founded in 1987 by the late Silicon Valley innovator and philanthropist David Packard. Our mission is to advance marine science and engineering to understand our changing ocean. Learn more at mbari.org.