Antarctic ecosystems could be disrupted by animals, disease and debris drifting from Africa and Australia as rising temperatures melt sea ice buffers, new research suggests.
The study, published in the journal Global Change Biology, used a simulation of ocean currents to track the paths of virtual objects released from different locations.
Simulations showed that objects from Australia, South Africa, South America and New Zealand were reached Antarctica every year, while objects from islands in the Southern Ocean came ashore even more frequently.
“Things can drift from much further north to Antarctica than we previously thought,” said Dr Hannah Dawson, the study’s lead author.
While alien species have not yet settled on Antarctic shores, the study suggests that waves and currents have carried objects from around the southern hemisphere to Antarctic shores for thousands of years.
“If things get there regularly, it has to be the cold water and the icy conditions that prevent it from actually settling,” Dawson said. “But these conditions are changing.”
Plants and animals that previously drifted to Antarctica may have been destroyed by the floating sea ice that constantly smashes and scrapes against the coastline. Alternatively, they might not have been able to survive the cold.
But as temperatures rise and sea ice melts, alien species will have a greater chance of colonizing the coastline. Antarctic sea ice has fallen to alarming lows for three years in a row.
Increasing plastic pollution also means that there is more debris for the animals to float on to travel south, after the number of plastic particles floating in the world’s oceans was found to exceed 170 tons in 2023.
Floating plastic can carry ants and diseases such as bird flu, while floating kelp and seaweed can transport crabs, starfish and snails, according to Ceridwen Fraser, the study’s co-author and a biogeographer at the University of Otago.
“It’s really worrying for the Antarctic species,” she said. “If foreign arrivals traveled and successfully settled the warm Antarctic coast, they would have a survival advantage over native species, which tend to grow more slowly.”
Dawson said: “They can outcompete local species and those local species will probably have nowhere else to go.”
The study also found that the Antarctic Peninsula would be the most vulnerable to colonization, with the vast majority of simulated items landing on the continent’s northernmost tip.
According to some models of climate change, the peninsula will be the first part of the continent to rise to temperatures that will allow overseas life to establish, according to Andy Hogg, director of the research facility ACCESS-NRI.
Hogg said the paper’s advanced modeling showed that scientists need to investigate which organisms from other continents can survive in Antarctic conditions and can survive on the coastline.
Jordan Pitt, an ocean mathematician at the University of Sydney, said the peninsula’s west coast was already regularly free of sea ice in the summer and would be a key place for researchers to watch for species arriving.
