As climate change transforms the planet, some organisms may flee their historic habitats for more hospitable areas. That can create challenges for the food webs and ecosystems already there, especially if those natural systems are delicate, as is the case in Antarctica.
An article published Friday (November 19) in Trends in Ecology & Evolution details the threats that nonnative species pose to Antarctica as climate change renders the landscape increasingly habitable to the seeds, insects, and other stowaways human travelers unknowingly traffic to the once-isolated continent. Right now, preventative measures are guided by the Antarctic Treaty, which lays out standards for the protection and management of the continent for its 54 signatory nations. The Scientist spoke to article author Dana Bergstrom, an applied ecologist with the University of Wollongong and the Australian Antarctic Division of Australia’s Department of Agriculture, Water, and the Environment, about the specific risks facing Antarctica’s endemic species, and how the international community can maintain and improve the Antarctic Treaty’s environmental protection provisions in order to prevent nonnative organisms from taking hold.
The Scientist: I imagine that there are lots of unique challenges inherent to ecological research in Antarctica. Are there any specific tools or techniques that you might not need in other environments that you find yourself relying on frequently?
Dana Bergstrom: You need to expect if you’re putting out equipment that it could be destroyed by nature of some kind, be it climate or extreme events.
You need patience and time to do what you want, because nature rules. A lot of the work that’s done with nonnative species is very low tech. It’s involved vacuum cleaners, searching through people’s boots. So not the sort of stuff that we’re doing with high-tech gene sequencing on bacteria. But we’re starting to combine the two. At the end of the paper, we talked about getting new technologies to discover nonnative species in a surveillance sense. One of the techniques you can do is to use eDNA. And that’s where we’re moving to—to be able to pick up that first arrival through eDNA as a signal as opposed to finding some needle in the haystack. So, the future opens up lots of possibilities to try and keep Antarctica as pristine as possible.
TS: You mentioned in your paper that Antarctica’s physical and ecological isolation led to an environment with low interspecific competition. Can you talk about how that historical balance works out? How did a situation where that competition isn’t really the driving factor come to be?
DB: If we go back to the age of the dinosaurs, you had a lot of tropical forests, some temperate forests, and maybe slopes that led to alpine areas. And so you would have had lots of lots of species. It [was] a very complex ecosystem: dinosaurs, small rodents. It was like something you would expect in southern South America now, or southern Tasmania.
Then, through the multiple glacial events, species were filtered out. . . . As the most extreme example, there’s this place called Mars Oasis, where there is a very tiny food web with only a handful of species. In the places I work in east Antarctica, the biggest thing you’ll have is a lichen. Springtails, which are tiny microinvertebrates, we find in some areas, but not where I work. When we had a springtail turn up in a hydroponic system in east Antarctica, it was like, “Whoa, this is a new thing, we have to work really hard to get rid of it,” and . . . we were successful.
[In most places in Antarctica] the biggest thing will be lichens, microbes in the soil, little tiny algae growing. And then if you go out toward the shore, it’s far more diverse because of the temperature. . . . Because they’ve been isolated, [sites in Antarctica have] a unique combination of species. There’s been very little connection between these places and the rest of the Southern Hemisphere.
TS: Can you talk about how the arrival of a new species threatens those isolated ecosystems?
DB: Take, for example, cushion plants [e.g. Azorella macquariensis], which are being hit by climate change. They have attributes to survive cold, but not attributes to be really competitive.
[Meanwhile,] Poa annua is one of the most extraordinary plants on the planet. Wherever it lands, it will cope to whatever conditions it finds. . . . [Native Antarctic species] don’t have the ability to exploit [rising temperatures] as much as Poa annua has.
As conditions change, those sorts of weedy species that are really good at taking over will take a hold. If there’s a hole in your food web where something can come in, then they have space and can become very dominant.
TS: It seems like there are two different categories of factors that are potentially, as you phrased it in your paper, “relaxing the barriers” to nonnative species in Antarctica. There are climate change-related factors, habitats changing. And then there’s people either intentionally or accidentally bringing something with them. Are there key differences between how those two mechanisms work, and do you handle them differently?
DB: I suppose I handle them together. . . . At the end [of the paper], I talk about the three As. It’s this thing that emerged out of Antarctic work, but we’re now applying it to ecosystem collapse across Australia.
[The] three As is one: awareness—understanding what’s there, what’s important to you, for value-based decision-making. Then [two is] anticipating the pressures. The pressures will be chronic, long-term changes. In the peninsula, there’s generally been a trend toward warming conditions in the near-shore environment, and certainly increased water temperatures. Then you have events like people arriving in a ship where there’s a possibility that any flying insects on board that ship can fly across to the station.
The third one is action to stop the pressures. Now, for the climate change pressures, it’s an international endeavor. But stopping propagules, stopping an insect flying from a ship to a station is something that could be done by a national program. So you look at it as a multifaceted problem, and you try and stop as many pressures, locally, as you can. Then [for] your big pressures, such as climate change, you put stock in international cooperation.
TS: You mentioned in your paper that nations and various signatories have adhered to the Antarctic Treaty fairly well, but you seemed less confident about the specific environmental protocol. I was curious if you could talk a little bit more about those regulations and what they’re designed to do, whether or not that seems to be the case.
DB: The signatory parties of the Antarctic Treaty, they’re really active . . . [and] operating in the [environmental protection] space with energy and alacrity. . . . But whether [the same standards get] applied all the time when people are going to Antarctica, we don’t really have clarity on because there hasn’t been any research looking at whether countries actually have the same standards they’re claiming.
There has to be this whole process because packing for Antarctica is actually really difficult. Imagine trying to maintain, on average, 5,000 scientists and personnel per year. And then you have the tourist people. Obviously, it stopped the last few years because of the pandemic, but before that there were tens of thousands of tourists. Now every person has their own bag, has their own shoes. All the food, all the requirements to maintain buildings and things like that. And to check every single item [for propagules] relies on a lot of a lot of goodwill—or faith in contracts.
We have, in the treaty, that any nation can go and inspect another nation’s activities. What I suggested is that it would be good to use those provisions in the treaty, for countries to say ‘We’re going to look at your biosecurity’ to another country.
TS: It sounds like there’s a certain level of rigor regarding scientific expeditions. How does that work with the tourism industry?
DB: The tourism industry—it’s high-end tourism, it’s very expensive. And so most people who do that have a high care for the environment. Whether it applies evenly across all the operators, we don’t know, because not everybody understands the treaty. And that is a challenge.
The treaty is working at the moment, but we know climate change is coming. There’s this moment in time where, if we can encourage what’s been so effective for so long, which is the international collaboration, then we can keep [Antarctica] pristine for native species.
TS: You mentioned in your paper that a number of nonnative species that had been brought over or arrived for whatever reason have failed to establish their own populations in Antarctica. Can you talk about why that is? Was it a matter of harsh environments or because you caught them early?
DB: It is a bit of both. So Poa annua has arrived at the peninsula and been removed by a treaty country. Poland, for example, is really active at the moment trying to get rid of Poa annua on King George Island. Other things, like various grasses and things found in continental Antarctica, they escaped and lasted a couple of seasons. Antarctica is tough, though. . . . As soon as the sun drops below the horizon, all of a sudden, things start to freeze. It can be extremely tough, and it can also be very drying. Without free water, [the nonnative species] may not establish [a population]. But my main worry is the near-shore environment, which is far more benign. If you’ve got starfish coming in through [recesses on ships], it can be very, very hard [to remove them]. But luckily, evidence is coming in that they haven’t survived.
If you can predict what’s going to be there, then you can come up with some genetic markers and use eDNA, which tells you what’s been in the environment. Then, if you can get to a population before it’s established, you improve your chance of removing it through eradication. What I hope will happen in the future is that we prepare. We should expect things coming into Antarctica but have all the tools and all our plans on how to get rid of them prepared so there’s none of that delay in action. We can be prepared and be proactive to keep Antarctica as pristine as possible.
TS: Can you talk a little bit more about the technical side of this genetic surveillance through eDNA. Is there a technique already in place that helps you do this search or is it something that you want to see established?
DB: eDNA is a new technique; it’s been developed over the last 10 years. There’s a lot of research going into [it] at the moment. If you take, for example, a water sample, you can see what’s been in that water sample over a short period of time. What you can then do is you can create specific markers for things that you know are risky, particularly the starfish. Or in the case of east Antarctica, we don’t have any springtails, but if you pick up markers for springtails, you can go search for them. And hopefully they haven’t expanded so you can eradicate them in a close proximity.
TS: So much of this centers around climate change, where habitats are being eradicated or otherwise rendered inhospitable for certain organisms. I was curious how you would approach the scenario where, say, a species has its historic environment destroyed, and maybe a changing Antarctica is where it finds refuge. How do you grapple with that versus trying to keep the ecosystem pristine as it is?
DB: Is [an arriving species] natural? Are we changing evolution? These are going to be the questions that managers ask. Are we stopping a natural process? What happens if you make the wrong decision? . . . Because colonization is going to happen, and we don’t really want to stop evolution. If it looks like something is a natural expansion, we want to leave it.
But if you’re not sure, it’s better to take it away and eradicate it early. It might be the wrong decision, but it’s an acceptable risk because if it’s a natural colonizer, then it’s going to come again. If it’s a nonnative species that’s been introduced by humans and we leave it there, that’s unacceptable. It’s important to have a decision tree already in place so when these events happen, you know how to respond. It saves time, because you never have enough time with a nonnative species coming in.
Editor’s note: This interview has been edited for brevity.