Printer-friendly versionSend to friendPDF version

The World Outside

A weekly column exploring issues relating to the environment, the future of our planet and that of mankind.

The Growing Threat From Alien Species

— Filed under: Science & Technology
The bullfrogs taking over Australia in the epi...

Image via Wikipedia

In my life I have been unfortunate enough to witness many shocking things in relation to the state of earth's ecosystems. Shortly after moving to the town of Katherine in the northern territory the cane toads also arrived like a biblical plague. One could hardly even drive on the road without running them over. Their poisonous glands also spelt doom for many native predators such as the Goanna and northern Quoll. Now the Cane toad has reached the borders of Western Australia. Introduced to Queensland in 1935 in hopes it would control the cane beetle it has since steadily spread across the continent leaving a trail of destruction.

I now live in Tasmania which is home to many smaller marsupials that have gone extinct on the mainland to introduced species such as the fox. However it is believed the fox has now made it here as well threatening the last major holdout for many unique species. On top of this the Tasmanian Devil has been driven to near extinction in the last few years by a facial tumour disease. The situation is just as bad or even worse in other parts of the planet such as Guam where the introduced brown tree snake has caused the extinction of many native species. Perhaps worst of all is New Zealand where introduced species now make up half of the fauna and many natives only survive on isolated islands.

However the impact extends to humans as well with West Nile virus now spreading across the United States, and millions being spent each year to control invasive species that damage infrastructure such as the Zebra mussel. I could go with other examples but the list of invasive species and the damage already caused is massive.

Once an invasive species becomes firmly established it is nearly impossible to get rid of it. Clearly more needs to be spent on prevention controls and rapid eradication if detected. This has been done successfully in the past such as the eradication of the African giant snail from Florida. Australia has also been leading the way with strict border controls and quarantine procedures. Restrictions on ships emptying their ballast tanks is another vital measure.

What have your experiences with invasive species been? Have you also witnessed this terrible worldwide plague?

Anonymous's picture

What's even crazier sometimes

What's even crazier sometimes is the extent to which people go to remove non-endemic species.  In Florida, they Army Corps of Engineers regularly dumps tons of chemicals in the Everglades to remove non-endemic flora! 

Ethan's picture

chemical solution

The Florida Everglades has been hit really badly by everything from invasive weeds to Burmese pythons and African Monitor Lizards becoming established there. I agree though the solution can sometimes be worse than the problem especially if the cure involves large amounts of pesticides and they can only somewhat temporarily control the problem as opposed to eliminating it.

I believe the best way forward is more to be spent on monitoring for new species coming in and then quick eradication when detected in conjunction with stricter controls and checks of international freight and passengers. Some places though like the Everglades have large established populations of invasive weeds and animals that will likely never be eliminated. Poisoning of the entire area is definately not the route I would hope governments continue with. Some of the invasive weeds can completely block up waterways and kill all the fish however.

Bernard's picture

Lost cause?

Greetings Ethan - excellent writing. Likewise an important topic, yet I fear it may be a sinking ship. With the world's population continuing to put strain on the Earth, and global travel increasing exponentially as it becomes financially viable for more people to traipse all over the place, we shall see more and more of this 'cross-pollination'. With millions hopping continents every day, is there any way to stop invasive species? I, for one, am skeptical. And as the anonymous poster before me mentioned, in some cases the remedy is worse than the infection.

Mayhaps we should just accept that in a few decades, the makeup of the world will be drastically different, and certain species will have won out over other, weaker ones?

Ethan's picture


Thanks Bernard

I definately see the truth in what you are saying but to go down that path would invite disaster for humanity. I really fear we are well on the way to causing mass extinctions and complete loss of biodiversity not seen since the Permian extinction. Unique places and their wildlife can be preserved and should be otherwise the world will be be a much duller place and all our lives will be that much less enriched. Imagine a world where the only bees are africanized ones. Where dogs and cats are top predators worldwide, and where the tropics no longer have the wonderful and diverse range of species they had. You are right though with globalization and a massively expanding worldwide population it will be difficult and countless species will be lost in the next few decades. But if we lose places like Tasmania which is the last major stronghold for Australia's smaller marsupials, and the last jungles in Asia that are home to the Orangutan then I think I collective futures will be very much diminished. Invasive species can cause much destruction to food production and the general environment as well. We cannot stop all of them but we can lessen the damage and preserve the unique places that are still left.