Keeping on top of invasive species

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Saturday 15 August 2015 12:30PM (view full episode)

Species which are moved long distances from their natural range often increase in number quickly as their natural predators are not present. In Australia, a common example is Lantana, the perennial flowering plant native to tropical regions of the Americas and Africa but which is now widespread throughout Australia. Lantana quickly multiplies outperforming native species. Invasive species can decimate crops. This explains why most governments take a serious approach to quarantine and inspections of goods crossing borders. Melodie McGeoch describes her work measuring and monitoring the impacts of invasive species on natural systems. Her group’s research frequently feeds into environmental policy and management.

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Robyn Williams: Melodie McGeoch at Monash University, meanwhile, is assessing invasions on our own terrain, and finding them far more extensive than you'd expect.

Melodie McGeoch: So, for example, we have a big field project in Chiltern-Mt Pilot National Park, which is about a three-hour drive north of Melbourne in a dry forest area, and there we are looking at the invasion of the understorey. And just for example, about 30% of the species richness in the understorey consists of foreign or alien species. So that just gives you some idea of the extent of the problem, and the fact that we in many cases are already dealing with novel ecosystems.

Robyn Williams: So how do you spot them and identify them in the field?

Melodie McGeoch: Well, that raises an important point because we depend heavily on good taxonomic information, so we need to be able to identify species, we need to know about what they look like. But my particular area of interest is at national scales, advising countries on how to measure invasive species, how to collate that information so that it is useful not only for tracking the state of the problem but also feeding into global information so that we understand globally how we are dealing with the problem, because invasive species are one of those problems that is really transboundary. The more countries trade with each other, the higher the risk of new species being introduced into new places and having unintended consequences. So we really need to have a global grip on the nature of the problem and how effective our measures are in dealing with it.

Robyn Williams: Well, recently on our program we've been dealing with the severe problem affecting citrus, that's oranges and lemons, plantations especially in America and Indonesia, where it's ruining the orange industry, and it seems almost out of control.

Melodie McGeoch: Well, those sorts of examples are very dramatic, and of course virtually all countries put measures in place, biosecurity measures, to prevent these worst-case scenarios from happening, but it is a reality that not only agricultural crop pests but also diseases do and will in future invade and wreak havoc. But those sorts of instances tend to be well documented, the economic and social consequences are well understood. I'm particularly interested in the impacts and the measurement and monitoring of invasive species on biodiversity, on natural systems, where we often don't pay as much attention and where we have a very vague understanding of the long-term consequences. We are not really able to convert the information into monetary value but we value our protected areas, our parks, our natural systems, and we know that they have…they are significantly important in terms of the ecosystem functions they provide.

Robyn Williams: And so far have you had any major successes?

Melodie McGeoch: We have. Countries have to report to the convention every five years. And it's remarkable when you look over the last decade or so how the information that countries are providing in these reports reveal quite clearly the fact that they are making progress in terms of the measures that they are implementing. That's not to say that we are really making progress in slowing the rate of invasion globally. On the one hand we don't actually have good quality enough information to say whether we do or not. In 2010, for example, only 11% of the world's countries were considered to have adequate information. We are really working hard to try and improve that number. And I'm optimistic that by 2020, which is the next major reporting period under the Convention, we will be in a much better position.

Robyn Williams: When they find the pest, what do they do about it?

Melodie McGeoch: Well, what you do about it depends on your understanding of how severe it is likely to be in terms of its impact. So part of what we do is work on ways of assessing the likelihood of a species having an impact, because the sheer numbers of species coming in is vast, and so you can't afford to focus on everything, you have to prioritise, and to prioritise you have to understand the relative impacts of species. So if it comes in and you know that it's likely to have a severe impact, then the important thing is to actually eradicate it immediately, and I call that early detection and eradication. So you really have to understand where it's most likely to come in, such as some of these agricultural pests, they have a very good understanding of where they are most likely to first observe the fruit fly or the scale insect or whatever it is that's going to impact the crop. And they have to invest a lot of effort in surveillance, and if it comes in then obviously systems are in place for rapid action to eradicate it.

Robyn Williams: And tell me, how good is the public at declaring what they are carrying at the borders and being aware of all this?

Melodie McGeoch: Notoriously not good in understanding the consequences of carrying fruit across borders. Australia is quite unique in that regard because of very good quality biosecurity measures at airports and so on, and that generates public awareness, but in many parts of the world there is very little focus and public awareness on these consequences of just carrying your semi-rotting apple from the US to Europe or vice versa.

Robyn Williams: Who'd want to bring a rotten apple from America? Just sloppy it sounds like. Melodie McGeoch at Monash University.


Melodie McGeoch
Associate Professor
School of Biological Sciences
Monash University
Melbourne VIC


Robyn Williams
David Fisher

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