Antarctica, Earth’s final frontier, may not be as isolated as we once believed. New evidence suggests that this pristine landmass, known for its unique species and ecosystems, faces a significant threat: the unwelcome arrival of non-native species.
These invasive species hitchhike on floating debris, such as marine pollution, from the landmasses of the Southern Hemisphere.
Unwanted visitors on a trip
Scientists from the University of New South Wales, ANU, the University of Otago and the University of South Florida have found that floating objects from unexpected places could well be Trojan horses for invasive species in Antarctic waters.
“The increasing amount of plastic and other human-made waste in the oceans means there are potentially more opportunities for biota to reach Antarctica,” said lead author Dr Hannah Dawson, who now works at the University of Tasmania.
Non-native species reach Antarctica
Scientists have long known that small marine invertebrates and other non-native species could reach Antarctica by riding on floating objects such as seaweed, driftwood, pumice and plastic.
The prevailing opinion was that these species only invaded from remote and uninhabited islands in the Southern Ocean.
However, new research paints a more comprehensive picture and shows that these species can reach the Antarctic coast from all southern continents.
Oceanic traffic patterns
“The objects released from South America have had the longest journey,” said Dr. Dawson. The reach of these new sources exceeds all expectations.
“We knew that seaweed can reach Antarctica from sub-Antarctic islands such as the Macquarie and Kerguelen Islands, but our study suggests that floating objects can also reach Antarctica from islands much further north, such as South America, New Zealand, Australia and South Africa,” noted Dr Dawson.
Antarctic ecosystems and invasive species
Southern kelp and giant kelp, some of the potential vectors of alien species, pose a potential double threat to the Antarctic marine ecosystem.
“Southern kelp and giant kelp are very large – often over 10 metres long – and provide a forest-like habitat for many small animals that can take them on the long raft journeys to Antarctica,” explains Professor Crid Fraser of the University of Otago. “If they colonise Antarctica, the marine ecosystems there could change dramatically.”
Movement of floating debris
The team analyzed surface current and wave data from 1997 to 2015 to track the movement of floating debris from various land sources in the Southern Hemisphere toward Antarctica.
“We were able to analyze how common these rafting connections are by simulating dispersal pathways over 19 years under different oceanographic conditions,” said study co-author Dr. Adele Morrison.
“We found that in each of the simulated years, raft objects reached the Antarctic coast. There seems to be a constant bombardment by anything that floats – be it seaweed or a plastic bottle.”
Climate change and species in Antarctica
The research also sheds light on the regions of Antarctica most at risk from alien species. Most of these sea-borne invaders are likely to land at the tip of the Antarctic Peninsula.
This area has relatively warm sea temperatures and often ice-free conditions that are ideal for the establishment of non-native species. The recent dramatic decline in Antarctic sea ice makes these results even more alarming.
“If the recent decline in Antarctic sea ice continues, it could become easier for creatures floating on the surface or attached to floating objects to colonise the continent, which could have major impacts on ecosystems,” Dr Dawson said.
Sensitization
Given that Antarctica and its native species may not be as well protected from marine invasion as previously thought, it is time to rethink our actions and their wider impacts.
As we stand on the brink of potentially irreversible changes in one of Earth’s most unique ecosystems, the findings of this study could well influence the decisions we make tomorrow.
Let’s resolve to be more conscious about waste disposal and take small steps today. Because the ripple effects of these steps could save an entire ecosystem tomorrow. What will be your next step?
The study was published in the journal Biology of global change.
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