A clump of southern bull kelp discovered on Antarctica’s King George Island.
Photo: Ceridwen Fraser

In 2017, marine biologist Erasmo Macaya was shocked to discover bits of kelp on the remote Antarctic island of King George, hundreds of miles from its natural habitat. He knew he’d found something strange, but he wasn’t aware he’d just uncovered evidence of a journey spanning over 10,000 miles—one that could portend a mass migration to the frozen continent as global temperatures rise.

Writing Monday in Nature Climate Change, Macaya and his colleagues report that the clumps of southern bull kelp (Durvillaea antarctica) he discovered in early 2017 traveled 20,000-25,000 kilometers (12,000-15,000 miles) before arriving on the shores of King George Island. The finding suggests that Antarctica—long presumed to be biologically sealed off by fierce circumpolar winds and ocean currents—may be more connected to the rest of the world than we thought.

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The researchers first used genomic analyses to determine that Macaya’s kelp specimens hailed from two source populations: the Kerguelen Islands in the southern Indian Ocean, and South Georgia island in the southern Atlantic. Using oceanographic models, they then traced each intrepid seaweed’s separate journey around the frozen continent, estimating that each would’ve had to bob along more than 10,000 miles before reaching its destination.

The researchers describe the journeys as “the longest biological rafting events ever recorded.”

Conventional wisdom holds that powerful winds known as the Roaring Forties, along with the Antarctic circumpolar current, effectively seal the continent off, pushing floating objects east and north and preventing them from reaching its shorelines. But when the authors incorporated an effect known as Stokes drift—where floating objects are pushed in their direction of surface waves—into their models, they showed it’s possible for objects to break through the barrier.

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“We found that when we included the effect of the surface waves in our modelling, as well as the ocean currents, crossings to Antarctica were relatively frequent,” study co-author Adele Morrison, an oceanographer at Australia National University, told Earther via email.

The findings are important not only because they highlight the incredible ability of life to disperse, but because of what they suggest about Antarctica’s future. While the continent has seen almost no natural colonizations from lower latitudes in tens of thousands of years, the new study argues that’s not for a lack of opportunity, but simply due to the harsh environment.

This suggests that Antarctica could be primed for ecological invasion as the climate changes. The researchers point out that not only were their southern bull kelp specimens still reproductively viable, the species is known to serve as a life raft for a variety of marine invertebrates.

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“If floating kelp and the other animals and plants that the kelp carries is regularly making its way to Antarctica, then it’s possible that as Antarctica warms, the climate there will become more hospitable to colonisations of these drifting plants and animals,” Morrison wrote. “This would bring dramatic ecosystem change to Antarctica.”

Of course, this is just a single scientific study, and the expectation that life can reach Antarctica relatively frequently is based on models. Morrison pointed out that climate change itself could affect the winds and storminess of the Southern Ocean in ways that make it easier or harder for life to disperse.

More research is needed to see if these model expectations hold in the real world, and if climate change does indeed help colonizers establish themselves on the frozen continent.

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But it’s an intriguing possibility, and one that reminds us that no place on Earth is safe from climate change’s effects.