We tend to think of Antarctica as isolated and biologically remote, that’s true. But the continent is busier than you might imagine, with many national programs and tour operators crisscrossing the world to get there.
And every ship, every cargo, and every person could harbor non-native species, hitchhiking south. This threat to Antarctica’s fragile ecosystem is what our new assessment, released today, is grappling with.
We have mapped the past five years of planes and ships visiting the continent, shedding light for the first time on the extent of movement across the hemispheres and potential locations of sources of non-native species, as shown in the map below. below. We have found that, fortunately, while some have made it through Antarctica, they have generally not yet taken control, leaving the continent still relatively pristine.
But Antarctica is getting busier, with new research stations, reconstruction and more tourist activities planned. Our challenge is to keep it intact in the face of this increasing human activity and the threat of climate change.
Life has evolved in isolation
From a biodiversity perspective, much of the planet is mixed. The scientific term is homogenization, where species, such as weeds, pests and diseases, from one place are transported elsewhere and become established.
This means that they begin to reproduce and influence the ecosystem, often to the detriment of the inhabitants.
Most of Antarctic life is stuck on tiny, ice-free coastal fringes, and this is where most research stations, ships, and people are located.
This includes unique animals (think Adlie penguins, Weddell seals, and snow petrels), mosses and lichens that are home to tiny invertebrates (such as mites, water bears, and springtails), and a fan. microbes such as cyanobacteria. The adjacent coast and ocean are also bustling with life.
The more we learn about them, the more exceptional life becomes at the end of the planetary spectrum. Just this week, new scientific findings have identified that certain Antarctic bacteria live in the air and make their own water using hydrogen as fuel.
When the Southern Ocean formed about 30 million years ago, natural barriers were created with the rest of the world. This includes the Antarctic Circumpolar Current, the strongest ocean current on the planet, and its associated strong westerly surface winds, freezing air, and ocean temperatures.
This means that life in Antarctica has evolved in isolation, with flora and fauna that typically don’t exist anywhere else and can cope with freezing conditions. But the simplicity of Antarctica’s food webs can often mean that there are gaps in the ecosystem that other species around the world can fill.
In May 2014, for example, routine biosecurity monitoring detected non-native springtails (tiny insect-like invertebrates) at a hydroponic facility at an Australian Antarctic station.
This station, an ice-free oasis, previously lacked these intruders, and they had the potential to permanently alter the fragile local ecosystem. Fortunately, a swift and effective response successfully eradicated them.
The pressures of climate change exacerbate the challenges for human activity in Antarctica, as climate change brings milder conditions to these wildlife-rich areas, both on land and at sea.
As glaciers melt, new areas are exposed, giving non-Antarctic species a greater opportunity to establish themselves and possibly to supplant inhabitants for resources, such as valuable nutrients and space and ice free.
So far we’ve been lucky
Our previous research has focused on non-native propagules that spread like microbes, viruses, seeds, spores, insects and pregnant rats and how they train in Antarctica.
They can be easily caught on people’s clothing and equipment, in fresh food, cargo and machinery. In fact, research over the past decade found that visitors who had not cleaned their clothes and equipment carried an average of nine seeds each.
But few non-native species have established themselves in Antarctica, despite their best efforts.
To date, only 11 species of non-native invertebrates, including springtails, mites, a midge and an earthworm, have established themselves in various places in the warmer regions of Antarctica, including Signy Island and the Antarctic Peninsula. In the marine realm, some non-native species have been observed, but none are believed to have survived and become established.
Germs are another matter. Every visitor to Antarctica carries millions of microbial passengers, and many of these microbes are left behind. Around most research stations, human gut microbes from sewage have mixed with native microbes, including swapping antibiotic resistance genes.
Last year, for example, a rare harmful bacterium, pathogenic to humans and birds, was detected in the guano (poo) of Adlie and Gentoo penguin colonies at sites with high levels of human visitors. COVID-19 also made its way to Antarctica last December.
Both of these cases pose a risk for reverse zoonosis, where humans transmit diseases to local wildlife.
What do we do about it?
Three factors have helped maintain Antarctica’s near pristine status: physical isolation, cold conditions, and cooperation among nations through the Antarctic Treaty. The Treaty is underpinned by the Environmental Protocol, which aims to prevent and respond to threats and pressures facing the continent.
There is a unanimous commitment by the Antarctic Treaty countries to prevent the establishment of non-native species. This includes the adoption of a science manual on non-native species, which provides advice on how to prevent, monitor and respond to introductions of non-native species.
But time is running out. We must better prepare for the inevitable arrival of more non-native species to prevent them from establishing themselves, as we continue to break down the barriers protecting Antarctica.
One approach consists of adapting the newly developed 3A approach to environmental management: Awareness of values, Anticipation of pressures, Action to stem pressures.
This means speeding up surveillance, taking note of predictions about non-native species that might sneak into biosecurity and become established under new conditions, and put in place predetermined response plans to act quickly when they do.
(The conversation: by Dana M Bergstrom, Principal Investigator, University of Wollongong and Shavawn Donoghue, Associate Researcher, University of Tasmania)