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Maybe you remember the iceberg A68a, which gained a few moments of fame when it broke an ice shelf on the Antarctic Peninsula in 2017. At 100 miles long and 30 miles wide, it was one of the largest icebergs ever seen.

The iceberg drifted slowly in the icy Weddell Sea for several years before collecting steam as it entered the Southern Ocean. The last time we heard from him, in 2020, It was heading towards the island of South Georgia in the South Atlantic.shrunk a little and battered from a journey of more than a thousand miles.

Unfortunately, the ol’ A68a is no longer available. Last year, about 100 miles from South Georgia, it finally did what all icebergs do: it got so thin that it broke into small pieces and eventually drifted into nothingness.

The A68a was about 800 feet thick at its best, but all but 120 feet of that was hidden below the waterline.

Ecologists and others feared that during its journey, the iceberg might run aground near South Georgia. This could have prevented the millions of penguins and seals that live and breed there from reaching their feeding grounds in the ocean.

This did not happen. New research shows that the A68a is making its way through more cars, and likely only hit a seafloor feature briefly as it turns and persists until it separates.

But the research also revealed another potential threat to the ecosystems around the iceberg’s South Georgia region. As it made its way from the relatively warm waters of the Southern Ocean to the South Atlantic, it melted from below, eventually releasing a large amount of fresh water into the sea near the island. Too much freshwater runoff can affect plankton and other organisms in the marine food chain.

Scientists led by Anne Braakmann-Folgmann, a doctoral student at the Center for Polar Observation and Modeling at the University of Leeds in England, used satellite imagery to track the shape and position of the iceberg throughout its journey. (It is named according to a convention established by the U.S. National Ice Center, which, like other large Antarctic icebergs, is slightly less flashy than the one used for hurricanes.)

The images showed how the area of ​​the iceberg changed over time. The researchers also determined the thickness of the ice using data from satellites measuring its height. Ms Braakmann-Folgmann said that when it disintegrated, A68a was less than 200 feet in total.

The A68a left its mark. Researchers with findings Published in the journal Remote Environmental Sensingestimates that melting around South Georgia has resulted in the release of approximately 150 billion tons of freshwater. That’s enough to fill an Olympic-sized swimming pool 61 million times, but since the ice is already floating, its melting didn’t contribute to sea level rise, the researchers said.

The water is not only sweet and salty, but also contains large amounts of iron and other nutrients. Ms. Braakmann-Folgmann is helping another group of researchers from the British Antarctic Survey trying to determine the ecological impacts of the iceberg and meltwater.

While the iceberg was near South Georgia, the scientists surveyed were able to use autonomous underwater gliders to take water samples. On the island, they used tracking devices on some gentoo penguins and fur seals to see if the presence of the iceberg was affecting their foraging behavior.

Biological oceanographer Geraint Tarling, who was involved in the study, said preliminary findings from monitoring data show that penguins and seals have not changed their foraging paths, as the iceberg may have blocked their path or affected their prey.

Dr. “At least in the parts of the colonies we’ve seen, the effects of the iceberg are not as devastating as we initially feared,” Tarling said.

However, Dr. Tarling suggested that there is more data to analyze, especially water samples. Large amounts of freshwater runoff at the surface could affect the growth of phytoplankton at the lower end of the food exchange or change the mix of phytoplankton species present, he said.

Complicating the analysis was that 2020, when the iceberg neared South Georgia, was also a bad year for krill, the tiny crustaceans found just above phytoplankton in the food chain.

Dr. Tarling said that although the A68a has not landed, a few more large icebergs have fallen in recent years. The grounding and drifting of an iceberg can wreak havoc on ecosystems on or near the seafloor, he said.

And climate change could potentially lead to more grounding periods. The warming is causing pieces of the massive Antarctic ice sheets to flow faster towards the ocean, causing further icing of the icebergs moving north later on.

Dr. “What we’re looking at is a lot more iceberg movement that could actually carve out these areas of the seafloor,” Tarling said.