Giant Antarctic ice split unveils ecosystem hidden for millennia

07 Oct 2017


When a vast trillion-tonne chunk of ice the size of Delaware broke free from Antarctica in July, it didn't just set loose one of the largest icebergs scientists have ever witnessed. The massive calving also uncovered a mysterious and precious marine ecosystem hidden under the ice that could have been buried for up to 120,000 years.

The vast ecosystem has been found in Antarctica's waters after the iceberg broke away from the Larsen C ice shelf, opening the possibility of new, undiscovered species having thrived underneath the ice during that time (See: The 1 trillion tonne iceberg).

According to Live Science, the iceberg codenamed A-68 is currently on a path toward the Weddell Sea as it continues floating away from the Larsen C ice shelf. It is expected to expose 5,800 sq km of seafloor that had remained under the iceberg without light for about 120,000 years.

According to the Daily Mail, scientists will need to be quick in exploring the increasingly exposed area, as the eventual loss of ice will likely result in significant changes to the once-hidden Antarctic ecosystem.

''It's just a fantastic, unknown area for scientific research,'' said British Antarctic Survey researcher Susan Grant in a statement. ''We know very little about what might or might not be living in these types of areas, and especially how they might change over time.''

Grant and her fellow BAS researchers were the ones who first theorised that there could be an Antarctic ecosystem where the A-68 iceberg used to be, and also have what the Daily Mail described as a ''fast-track'' proposal brought on by the iceberg's calving. But they won't be alone in launching studies that hope to determine just what kind of animal species exist in the area. Two missions – one from South Korea and the other from Germany's Alfred Wegener Institute for Polar and Marine Research – could result in missions in 2018 or 2019, respectively.

Nonetheless, Live Science noted that the BAS' proposal to implement protections on the Larsen C area was the first to be chosen by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) in 2016. The proposal includes a designation of the area for scientific research, and to that end, a two-year moratorium on commercial fishing and tourism.

This ban on commercial activities could be extended for another 10 years after the initial two years expires, and could potentially be turned into an indefinite ban after the 10-year extension is up.

Speaking to Live Science, Grant explained that the new Antarctic ecosystem could suffer through some changes when the ice moves away, but there is no proof at the present that the calving event directly resulted from climate change.

''We do expect that these sorts of things may happen more frequently in the future, so understanding how things respond to this kind of change is really important,'' she continued.

Grant's colleague, BAS head of conservation ecology Phil Trathan, explained that scientists' knowledge of Antarctic ecosystems found beneath the continent's ice shelves is ''mainly limited'' to two long German expeditions where scientists tried to find similar signs of new ecosystems underneath the Larsen A and Larsen B shelves. He added that the long periods of time to get to the areas might have resulted in colonization by new species.

''You'll have sunlight, you'll have phytoplankton, and you'll begin to get zooplankton and fish in there pretty quickly. You'll probably also get seabirds and marine mammals are going to begin to forage in that area,'' said Trathan.

''So, it will be sort of a chain reaction - as you get productivity happening then you'll get more species coming in, and so there will be quite significant changes over relatively short time scales.''

Julian Gutt, a marine biologist with the Alfred Wegener Institute, spoke from experience when he discussed the types of animals that could be found in the exposed seafloor. Gutt, who led scientific expeditions to Larsen A and Larsen B in 2007 and 2012 respectively, recalled seeing sea cucumbers, sponges, sea stars, and other underwater animals.

And while the findings may or may not be different when scientists make it to the site of the new Antarctic ecosystem, he added that it will ultimately be more important to determine how fast marine species respond to environmental changes, including, but not limited to, climate change.

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