Visitors to Australia are often shocked at having to declare an apple or wooden item under our biosecurity policies . Biosecurity policies are used to keep out pest species and diseases. But they're expensive to uphold and people can question their worth .
Authors
- Rachel Leihy
Ecologist, Arthur Rylah Institute for Environmental Research
- Melodie McGeoch
Professor of Ecology, Monash University
- Steven Chown
Director, Securing Antarctica's Environmental Future and Professor of Biological Sciences, Monash University
The good news is, they work - and Antarctica's strict biosecurity policies prove it.
Under the web of agreements governing Antarctica, cargo must be checked for any sign of plants, seeds, insects and rodents. Visitors must ensure the items they bring are clean.
In our new research , we analysed a century of data on how many species have been introduced to the icy continent and surrounding sub-Antarctic islands.
Though there's little human presence here, many species have been introduced and several have established - including rodents, aphids, and weedy plants - in a surprisingly short time. But across most sub-Antarctic islands, we found the rate of introduced species has remained steady, or slowed, after biosecurity policies were introduced, even as more humans arrived.
The exception was the Antarctic continent itself, where species introductions are increasing. This is likely due to surging visitor numbers and inconsistent biosecurity efforts between different nations and tourist operators.
Our work shows biosecurity policies work - if they're followed.
Biosecurity in the cold
Antartica and sub-Antarctic islands such as Heard and McDonald Islands have an exceptional richness of species. Wandering albatrosses and emperor penguins live nowhere else. Some islands are home to meadows of megaherbs .
Unfortunately, introduced species have had dramatic effects. Mice eat albatrosses alive . Midges entirely change the functioning of terrestrial systems. Weedy plants outcompete and displace unusual plants on several islands.
Antarctic environments are particularly susceptible to introduced species. New species tend to have faster life cycles and are more tolerant of disturbance. Most indigenous species evolved without predators or competitors.
As the climate heats up, introduced species get a boost. Warmer conditions make it easier for them to get their first foothold, and they do better with warmer climates than do the indigenous species.
These vulnerabilities are why nations responsible for sub-Antarctic islands and those who jointly govern Antarctica through the Antarctic Treaty put strict biosecurity protocols in place from the 1990s onwards.
These policies ban the deliberate introduction of new species and specify the measures visitors and cargo have to undergo to reduce the chance of new species being introduced accidentally.
These protocols include cleaning equipment, clothing and cargo. In many cases, these policies also require eradication of any potentially damaging species if found.
Is it worth it?
All this takes time and money. To do it properly requires many hours of inspections and specific facilities, among other things. Ongoing research is also needed, to ensure the policies keep working.
But eradication of species once established is often even more expensive. Costs are rising globally . Invasive species have cost Australia at least A$390 billion since the 1960s. Eradicating introduced rabbits, rats and mice from Australia's Macquarie Island cost about A$25 million .
So, are our biosecurity efforts worth the cost?
Assessing the effectiveness of biosecurity policies is rare because it is difficult. To properly gauge effectiveness, you need data from before and after the policy came in. It's also hard to pinpoint when a species made the jump to the cold; it's harder to spot one new plant than a thriving population years after the first seeds took root.
We believe our work solves these problems. We collected data on species arrivals across the Antarctic region and corrected for biases using new mathematical approaches that account for differences in survey effort over time.
Most species introductions now happen by accident. Because introductions are closely tied to the numbers of visitors, we expected more species would arrive as visitor numbers grew. But on most sub-Antarctic islands, that didn't happen. Species arrived at the same rate or more slowly than expected, even as more visitors came.
In other words, the policies are working.
Why is Antarctica the exception?
Since 1998, biosecurity policies for the Antarctic continent haven't managed to slow the rates of introductions.
Newly introduced species are largely being found on the Antarctic Peninsula, where most tourists and scientists go. The peninsula has the mildest climate of the whole continent and is where Antarctica's native flowering plants are found, as well as mosses, lichens and fungi.
The new arrivals include annual bluegrass which displaces native plants. Also arriving are invertebrates, such as midges and springtails which can alter how nutrients are cycled in soil and shift other ecosystem functions.
It's not fully clear why biosecurity policies aren't working as well on the continent as for the islands. Likely causes include inconsistencies in how biosecurity is policed by different nations, a rapidly warming climate and very rapidly growing numbers of people to the peninsula.
What does this mean for the world?
Introduced species are one of the largest environmental and economic challenges we face, according to an authoritative recent assessment .
This may seem surprising. But the unchecked impact of species such as red fire ants, varroa mite and feral pigs cost Australian farmers billions each year . Prevention is usually better - and cheaper - than the cure.
What our research shows is that biosecurity policies actually work to protect the environment and are likely to be cheaper than the cost of control or eradication. Introduced species now cost the global economy an estimated $423 billion annually.
Society and decision-makers can see environmental regulations as a cost without a benefit. Being able to show the real advantages of these regulations is vital.
Rachel Leihy works for the Arthur Rylah Institute for Environmental Research and Monash University, Melbourne, Australia. This research was done as a part of the Australian Research Council funded program Securing Antarctica's Environmental Future.
Melodie McGeoch receives funding from the Australian Research Council - SRIEAS Grant SR200100005 Securing Antarctica's Environmental Future.
Steven Chown receives funding from the Australian Research Council. He is an Honorary life member of the Scientific Committee on Antarctic Research.
