Chicago-Sized Iceberg Hid Ancient Ecosystem, Scientists Reveal

Scientists scrutinizing the seafloor beneath a calving iceberg found a remarkable array of living creatures, switching up notions of how the giant chunks of ice affect their immediate environs.

The scientists investigated a region of seafloor recently exposed by the calving of a gigantic iceberg—A-84—which is as large as Chicago. The team found a surprisingly vibrant community of critters on the seafloor below where A-84 was once attached to an ice shelf attached to Antarctica.

“We didn’t expect to find such a beautiful, thriving ecosystem,” said Patricia Esquete, the expedition’s co-chief scientist and a researcher at the University of Aveiro in Portugal, in a British Antarctic Survey release. “Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Without the 197-square-mile (510-square-kilometer) iceberg in the way, the team was able to scrutinize the seafloor at depths of 4,265 feet (1,300 meters) using the remotely operated vehicle (ROV) SuBastian. The team found large corals and sponges supporting other lifeforms, including icefish, giant sea spiders, and octopus.

The scientists who made the discovery were part of a team aboard the Schmidt Ocean Institute’s R/V Falkor (too), a 363-foot-long (111-meter) vessel that’s regularly revealing hidden details of life at the bottom of Earth’s oceans. The vessel has previously mapped unknown areas of the ocean floor and even captured the intimate breeding grounds of octopuses.

With the icebergs covering the seafloor, organisms below the shelf cannot get nutrients for survival from the surface. The team hypothesized that ocean currents are a critical driver for life beneath the ice sheets. The team also collected data on the larger ice sheet, whose shrinking size spells concern for the animals that live beneath it.

“The ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said the expedition’s other co-chief scientist, Sasha Montelli, a researcher at University College London, in the same release. “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.”

Though the ice shelf disappearing is worrying, it also creates an opportunity for scientists to explore an area that is otherwise even harder to access. ROV SuBastian and R/V Falkor (too) will almost certainly make new discoveries about extreme environments where life ekes out existence before their journeys are brought to an end.