Antarctica’s unique ecosystem is threatened by invasive species hitchhiking on ships


Antarctica has been relatively isolated from the rest of the world for millions of years, but nowadays ships could potentially introduce marine animals and algae. Invasive species can have dramatic consequences on ecosystems, for example by invading areas and creating new habitat or by becoming predators for species without proper defences.

The best way to protect against this is to prevent any non-native species from arriving in the first place. Of course, any new species would still need to survive in the freezing waters around Antarctica, but it turns out that ships usually visit the areas that are warming fastest due to climate change.

Aside from a few seals, whales and migrating birds, Antarctica’s unique marine life has been largely cut off by Southern Ocean currents that spin clockwise around the continent and divert most of the floating organisms. Arriving species, possibly attached to drifting kelp, face year-round low temperatures and strong seasons.

Although this barrier has existed for millions of years, ships allow species to reach Antarctica and its coastal waters that otherwise would never have been able to make the journey. Reaching the Antarctic coast from sub-Antarctic islands can take up to three years for species associated with kelp rafts. The same species could make the same trip in a few days if attached to the hull of a ship.

Map the risk of invasion

What could this mean for Antarctica and its ecosystem? In my academic research, I hunt non-native species that live on the hulls of ships that visit the continent, and I study where those ships go. I’ve scraped hulls and pipes, stripped barnacles and sludge from ships to find out what species are already being transported there and where in the world they come from. These ships travel the world, with many visiting the Arctic and Antarctica regularly each year, usually via the Atlantic. Their hulls are usually only cleaned every two years and can carry anything from mussels and crabs to barnacles, amiphodes (shrimp-like crustaceans), bryozoans, hydroids (similar to anemones or jellyfish) or algae.

According to my latest study, published in the journal PNAS, ships in Antarctica are most likely to introduce organisms from southern South America, northern Europe, or the western ocean. Peaceful.

Port-to-port traffic network of all ships that visited Antarctica 2014-2018.
David Aldridge, Author provided

Most voyages reach Antarctica via one of five recognized gateway cities – Punta Arenas (Chile) and Ushuaia (Argentina) in South America, Hobart (Australia), Christchurch (New Zealand) and Cape Town (South Africa). South). However, our study revealed that an additional 53 berths served as departure ports.

There are certain safety measures ships could take, such as special hull coatings that algae and animals cannot adhere to very well, or regular hull cleanings. Countries could require proof of a clean hull or regular inspections before allowing ships to enter certain areas.

Although logistically complex, these measures are being adopted around the world in places like Hawaii, the Galapagos Islands, New Zealand and Australia, and can provide examples of strategies to reduce the introduction of non-native species in Antarctica via ships. With the support of the Antarctic community, these ports of entry could become places for biosecurity checks before ships depart for Antarctica.

About 100 to 200 ships visit Antarctica each year, an increase of up to 10 times since the 1960s. The vast majority stick to two particularly accessible regions, the Antarctic Peninsula and the South Shetland Islands, which means that these areas are most at risk.

Activities on the continent and in the Southern Ocean are largely divided between research and its support carried out by national operators, tourism and fisheries. The top 20 potential invasion hotspots are locations visited by combinations of tourist, research, fishing, or supply vessels. While tourism accounted for 67% of visits to all Antarctic sites (followed by research 21%, fishing 7%, supply 5% and other 1%), research vessels were the only ones with connections with all areas of the continent.

A small crab
European shore crab Carcinus maenas found alive on a ship that visited Antarctica and the Arctic.
Arlie McCarthy, Author provided

Therefore, different locations as well as each type of activity require tailored, yet consistent, biosecurity practices. We urgently need to make sure everyone in the region works together to search for new species.

Don’t move a mussel

So far, researchers have only found five non-native species living freely in Antarctic waters, which were likely introduced through human activities. These include Chilean mussels, just like the ones we eat, and a type of crab. Although many other species live on the hulls of Antarctic ships, mussels and crabs are of particular concern because there are no similar animals in the continent’s shallow waters.

Metal grid with stuff stuck on it.
Barnacles, algae and small crustaceans stuck to a ship that visited Antarctica and the Arctic every year of the study period.
Arlie McCarthy, Author provided

Mussels could potentially create a new type of habitat, ‘mussel beds’, which could outcompete local species or allow the arrival of even more non-native species. Crabs would represent a new type of predation against which local species may not be able to defend themselves. Although concerning, it remains a mystery whether or not these animals could survive and establish populations in Antarctica long-term or, indeed, if they will actually have any negative effects on native marine life.

For now, Antarctica and the Southern Ocean remain the least invaded marine regions on the planet and represent humanity’s last chance to demonstrate that we can manage and mitigate the risks of invasive species at scale. continental. If we don’t, climate change will open the door to the world and our neglect will transform the iconic ecosystems we love.

Read more: Polar invasion: how plants and animals would colonize an ice-free Antarctica


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