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Objects that wash ashore in Antarctica could carry non-native floral and faunal species, which can disrupt native species if they are able to survive the cold conditions, researchers warned.
Passively floating objects can drift to Antarctica not only from sub-Antarctic islands, but also from continental locations north of the subtropical front including Australia, South Africa, South America and New Zealand, according to the study published in the journal Global Change Biology August 21, 2024.
The Antarctic Peninsula is the area most vulnerable to the introduction of non-native species, which arrive through natural oceanic dispersal as well as via ship traffic and rapid warming.
The study highlighted that the severe environmental conditions in Antarctica hinder the establishment of numerous species. However, rising temperatures and the emergence of ice-free areas might already be lowering these barriers.
The extensive links with sub-Antarctic and temperate regions, along with a growing number of marine human-made rafting vectors, present an increasing threat to Antarctic marine ecosystems. This risk is particularly concerning as future environmental conditions around Antarctica are expected to become more favourable for non-native species.
Researchers used "0.1° global ocean model simulations to explore whether drift connections exist between more northern, temperate landmasses and the Antarctic coastline".
Virtual particles, symbolising drifting objects, were released from ten sub-Antarctic and Southern Ocean islands and continents. These sites were selected because they host the southern bull kelp species known for long-distance rafting (including South America, South Georgia, Crozet Islands, Gough Island, Kerguelen Islands, Macquarie Island, Marion Island, and New Zealand), or they are potential sources of plastic, driftwood, giant kelp, and other ocean debris (Australia, South Africa, New Zealand, and South America).
The particle tracking simulations indicated that the Antarctic coastline is widely connected to southern landmasses, including all southern hemisphere continents.
The study indicated that debris, including plastic, might facilitate the arrival of non-native animals such as molluscs to Antarctica from southern continents and islands.
A majority of the connectivity originates from the sub-Antarctic islands: Macquarie Island exhibits the highest connectivity with Antarctica, followed by Kerguelen Islands and South Georgia. Among these three locations, a total of 814 particles per 100,000 released (0.8 percent) reached the Antarctic coastline within three years.
Australia (Tasmania) demonstrated the lowest connectivity with Antarctica, closely followed by South Africa and Gough Island (an island in the South Atlantic Ocean).
From these three locations, only three particles per 10 million released reached the continent. Researchers used the example of the southern bull kelp Durvillaea antarctica, an algae with long-range dispersal potential that can remain reproductively viable for extended periods at sea, to emphasise the threat to Antarctic ecosystems.
Ceridwen I Fraser, University of Otago, New Zealand and co-author of the study said that that kelp could deal a potential double whammy blow to Antarctica’s marine ecosystem.
“Southern bull kelp and giant kelp are very big – often more than 10 m long – and create forest-like habitat for a lot of small animals, which they can carry with them on the long rafting trips to Antarctica. If they colonise Antarctica, marine ecosystems there could change dramatically," Ceridwen I Fraser said.