Record-breaking seaweed that travelled 12,500 miles to Antarctica proves animals including worms and snails could one day use ‘living’ rafts to populate the icy continent
- A portion of seaweed was tracked using its DNA back to its original source
- It came from as far afield as the Kerguelen Islands and South Georgia
- The kelp does not grow in Antarctica but it can float and carry small creatures
- Global warming could make the wilderness habitable for new marine life
Clumps of kelp found on a beach in Antarctica travelled more than 12,500 miles (20,000km) to get there in the longest biological rafting event ever recorded.
Using DNA tests, scientists identified the kelp as a species native to the remote South Georgia islands off the coast of Argentina and the Kerguelen Islands, southwest of Western Australia.
They believe it ‘surfed’ to King George Island, just off the Antarctica Peninsula, after getting caught up in storms that helped it breach the Southern Ocean’s strong polar winds and currents.
Scientists have long thought those winds and currents act as natural barriers to stop plants and most animals from reaching the frozen continent – including small creatures that are known to migrate to new habitats on clumps of seaweed.
The presence of seaweed at Antarctica so far from its origins indicates that other plant and animal species, including worms, snails and crustaceans could one day live there as global warming makes the hostile environment more habitable.
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Clumps of seaweed that travelled 12,500 miles to Antarctica proves animals including worms and snails could one day use ‘living’ rafts to populate the icy continent. Pictured is the route taken by the kelp
The study found that the kelp that washed up on the icy shores of Antarctica was covered in barnacles, a telltale sign that the kelp had been drifting for a long time.
By mapping the complete DNA of the specimens, the researchers found one had almost certainly originated in Kerguelen in the Southern Indian Ocean and another from South Georgia in the South Atlantic Ocean – over 12,500 miles (20,000 km) from the beaching site.
Dr Erasmo Macaya, of the University of de Concepcion in Chile, who found the foreign seaweed, said: ‘I knew when I saw this floating seaweed – southern bull kelp – that it was important.
The kelp does not grow in Antarctica but it can float and act as a raft, carrying many other intertidal plants and animals with it across oceans.
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It was previously believed Antarctic plants and animals were different to those found elsewhere in the world.
But the latest findings indicate these differences are almost entirely due to environmental extremes rather than physical isolation.
‘If those rafts can make it this far we could soon see massive changes in Antarctic intertidal ecosystems,’ Dr Macaya said.
Lead researcher Dr Crid Fraser revealed the kelp essentially surfed to Antarctica – with the help of winds caused by storms.
Clumps of kelp found on a beach in Antarctica travelled more than 12,500 miles (20,000km) to get there in the longest biological rafting event ever recorded. Pictured left and right are portions of the specimen tested by scientists
To reach Antarctica, the seaweed (yellow and blue) had to navigate the Antarctic Polar Front, a barrier of jets and flows (purple shows current speeds) that separates Antarctic and sub-Antarctic waters to the north, which was thought impossible
Dr Fraser, of The Australian National University in Canberra, said: ‘These are astonishing voyages, but worrying too.
‘They show Antarctic ecosystems could be more vulnerable to global warming than we had suspected.
‘Parts of Antarctica are among the fastest warming places on Earth.
‘If plants and animals get to Antarctica fairly frequently by floating across the ocean, they will be able to establish themselves as soon as the local environment becomes hospitable enough.’
Some of the seaweed made it to Antarctica after the epic journey (yellow), but some clumps drifted northwards (blue)
The study found that the kelp that washed up on the icy shores of Antarctica (pictured) bore signs of drifting a long time at sea as they were covered in barnacles
They had to navigate the Antarctic Polar Front, a barrier of jets and flows that separates Antarctic and sub-Antarctic waters to the north, which was thought impossible.
Dr Fraser said: ‘This is an unequivocal demonstration that marine species from the north can reach Antarctica.
‘To get there, the kelp had to pass through barriers created by polar winds and currents that were, until now, thought to be impenetrable.
‘This finding shows us living plants and animals can reach Antarctica across the ocean with temperate and sub-Antarctic marine species probably bombarding Antarctic coastlines all the time.
By mapping the complete DNA of the specimens, the researchers found one had almost certainly originated in Kerguelen in the Southern Indian Ocean and another from South Georgia in the South Atlantic Ocean
Detached kelp (pictured) can drift thousands of kilometres across oceans. Researchers reveal the kelp essentially surfed to Antarctica – with the help of winds caused by storms
‘We always thought Antarctic plants and animals were distinct because they were isolated.
‘But this research suggests these differences are almost entirely due to environmental extremes, not isolation.’
Kelp is a keystone species in Antarctica, playing a vital role in the food chain and supporting a diverse array of plants.
The study also sheds fresh light on the science of ocean drift, a phenomenon that has recently been found to be carrying microplastics produced by humans all the way to Antarctica.
While conditions on the frozen continent are currently too cold for most organisms to survive, global warming could make the wilderness habitable for new marine life such as worms, snails and crustaceans
Dr Fraser said: ‘Our findings also indicate plants and animals living on Antarctica could be more vulnerable to climate change than we had suspected.’
Using cutting-edge computer modelling, the international team showed how large waves arising during storms helped kelp rafts reach Antarctica.
Co-researcher Dr Adele Morrison, also from The Australian National University, said: ‘Once we incorporated wave-driven surface motion – which is especially pronounced during storms – suddenly some of these biological rafts were able to fetch up on the Antarctic coastline.
‘If plants and animals get to Antarctica fairly frequently by floating across the ocean, they will be able to establish themselves as soon as the local environment becomes hospitable enough.
‘Strong westerly winds and surface currents are expected to drive floating objects north and away from Antarctica, but when the disruptive influence of Antarctic storms is factored in, that all changes.’
WHAT DO RECENT STUDIES REVEAL ABOUT ANTARCTICA?
A special issue of Nature has published a series of studies looking at how monitoring Antarctica from space is providing crucial insights into its response to a warming climate.
Here are their key findings:
Three trillion tonnes of ice has been lost from Antarctica since 1992
The Antarctic Ice Sheet lost around three trillion tonnes of ice between 1992 and 2017, according to research led by Leeds University.
This figure corresponds to a mean sea-level rise of about eight millimetres (1/3 inch), with two-fifths of this rise coming in the last five years alone.
The finds mean people in coastal communities are at greater risk of losing their homes and becoming so-called climate refugees than previously feared.
In one of the most complete pictures of Antarctic ice sheet change to date, an international team of 84 experts combined 24 satellite surveys to yield the results.
It found that until 2012 Antarctica lost ice at a steady rate of 76 billion tonnes per year – a 0.2mm (0.008 inches) per year contribution to sea level rise.
However, since then there has been a sharp, threefold increase.
At some point since the last Ice Age, the West Antarctic Ice Sheet was smaller than it is today
Researchers previously believed that since the last ice age, around 15,000 years ago, the West Antarctic Ice Sheet (WAIS) was getting smaller
However, new research published by Northern Illinois University shows that between roughly 14,500 and 9,000 years ago, the ice sheet below sea level was even smaller than today.
Over the following millennia, the loss of the massive amount of ice that was previously weighing down the seabed spurred an uplift in the sea floor.
Then the ice sheet began to regrow toward today’s configuration.
‘The WAIS today is again retreating, but there was a time since the last Ice Age when the ice sheet was even smaller than it is now, yet it didn’t collapse,’ said Northern Illinois University geology professor Reed Scherer, a lead author on the study.
‘That’s important information to have as we try to figure out how the ice sheet will behave in the future’, he said.
The East Antarctic Ice Sheet was stable throughout the last warm period
The stability of the largest ice sheet on Earth is an indication to scientists that it could hold up as temperatures continue to rise.
If all the East Antarctic Ice Sheet melted, the sea level would rise by 175 feet (53 metres).
However, unlike the Greenland and West Antarctic ice sheets it seems it would be resistant to melting as conditions warm, according to research from Purdue University and Boston College.
Their research showed that land-based sectors of the East Antarctic Ice Sheet were mostly stable throughout the Pliocene (5.3 to 2.6 million years ago).
This is when carbon dioxide concentrations in the atmosphere were close to what they are today – around 400 parts per million.
‘Based on this evidence from the Pliocene, today’s current carbon dioxide levels are not enough to destabilise the land-based ice on the Antarctic continent,’ said Jeremy Shakun, lead author of the paper and assistant professor of earth and environmental science at Boston College.
‘This does not mean that at current atmospheric carbon dioxide levels, Antarctica won’t contribute to sea level rise.
‘Marine-based ice very well could and in fact is already starting to contribute, and that alone holds an estimated 20 meters of sea level rise,’ he said.
Decisions in the next decade will determine whether Antarctica contributes to a metre of sea level rise
One of the largest uncertainties in future sea-level rise predictions is how the Antarctic ice sheet reacts to human-induced global warming.
Scientists say that time is running out to save this unique ecosystem and if the right decisions are not made in the next ten years there will be no turning back.
Researchers from Imperial College London assessed the state of Antarctica in 2070 under two scenarios which represent the opposite extremes of action and inaction on greenhouse gas emissions.
Under the high emissions and low regulations narrative, Antarctica and the Southern Ocean undergo widespread and rapid change, with global consequences.
By 2070, warming of the ocean and atmosphere has caused dramatic loss of major ice shelves, leading to increased loss of grounded ice from the Antarctic Ice Sheet and an acceleration in global sea level rise.
Under the low emissions and tight regulations narrative, reduction of greenhouse gas emissions and implementation of effective policy helps to minimise change in Antarctica, which in 2070 looks much like it did in the early decades of the century.
This results in Antarctica’s ice shelves remaining intact, slowing loss of ice from the ice sheet and reducing the threat of sea level rise.
What saved the West Antarctic Ice Sheet 10,000 years ago will not save it today
The retreat of the West Antarctic ice masses after the last Ice Age was reversed surprisingly about 10,000 years ago, scientists found.
In fact it was the shrinking itself that stopped the shrinking: relieved from the weight of the ice, the Earth crust lifted and triggered the re-advance of the ice sheet.
According to research from the Potsdam Institute for Climate Impact Research (PIK) this mechanism is much too slow to prevent dangerous sea-level rise caused by West Antarctica’s ice-loss in the present and near future.
Only rapid greenhouse-gas emission reductions can, researchers found.
‘The warming after the last Ice Age made the ice masses of West Antarctica dwindle,’ said Torsten Albrecht from the Potsdam Institute for Climate Impact Research.
‘Given the speed of current climate-change from burning fossil fuels, the mechanism we detected unfortunately does not work fast enough to save today’s ice sheets from melting and causing seas to rise.’
The world’s ice shelves may be being destabilised by forces from above and below
Researchers found that warm ocean water flowing in channels beneath Antarctic ice shelves is thinning the ice from below so much that the ice in the channels is cracking.
Surface meltwater can then flow into these fractures, further destabilising the ice shelf and increasing the chances that substantial pieces will break away.
The researchers, led by the University of Texas at Austin, documented this mechanism in a major ice break up, or calving, event in 2016 at Antarctica’s Nansen Ice Shelf.
The findings are concerning because ice shelves, which are floating extensions of continental glaciers, slow down the flow of ice into the ocean and help control the rate of sea level rise, according to the study.
‘We are learning that ice shelves are more vulnerable to rising ocean and air temperatures than we thought,’ said Professor Christine Dow, lead author of the study.
‘There are dual processes going on here. One that is destabilising from below, and another from above.
‘This information could have an impact on our projected timelines for ice shelf collapse and resulting sea level rise due to climate change’, he said.
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