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The Extinction and Conservation of Australia’s Biodiversity

JODIE RAMODIEN | NEWS



Grapeshot interviews Jaco Le Loux, Associate Professor in the department of Biological Sciences at Macquarie University.


In conversation with Jaco Le Loux:


What are some of the major threats posed to Australian wildlife?


Like elsewhere in the world, the main culprits are human-mediated climate change, habitat destruction, and invasion by exotic species. Australia is special in that the continent has been isolated for tens of millions of years and has therefore exchanged very little biota with other continents historically. This, in part, resulted in the evolution of very remarkable animals and plants, found nowhere else on Earth, that may be particularly vulnerable to novel threats.


How has climate change affected biodiversity in Australia?


There is no doubt that climate change negatively impacts most species, especially those with small population sizes and limited dispersal opportunities, like threatened plants. Climate and its interactions with other abiotic conditions, as well as with organisms themselves, are complex. Therefore, ascribing the extinction of a particular species to climate change per se is difficult. Yet, the impacts of climate change on biodiversity is undeniable. For example, sea surface temperatures were largely responsible for the low rainfall and humidity that Australia experienced in 2019 which, in turn, contributed to the devastating 2019-2020 Black Summer fires. Some scientists have estimated that more than 800 million animals may have perished in NSW alone during these fires. We also know that large parts of the natural habitats of many native species were burned down. The recent Bureau of Meteorology (BOM) “State of the Climate 2020” report suggests that Australia will experience even warmer temperatures, drier periods, and more extreme events in the future, spelling disaster for our unique biodiversity.


What is the impact of invasive species on extinction rates among Australian flora and fauna?


The impacts of invasive species on native Australian biodiversity are massive. Let’s consider mammal extinctions. In other parts of the world the primary drivers of mammal extinctions are habitat loss and hunting, but in Australia only two (!) invasive species (cats and European red foxes) have been responsible for the extinction of most of the 30 or so extinct native mammals. Some have argued that Australia’s historical isolation may underlie these devastating impacts, as many native Australian species lack evolutionary experience to mesopredators like cats and foxes. Similarly, native plants with little or no evolutionary experience with invasive animals like camels and brumbies (Australia has no native hoofed animals) have been severely impacted through trampling and grazing.


Have we been able to improve the status of threatened species through conservation practices?


There is a lot going on in the conservation arena in Australia, with numerous initiatives at both state and national levels. Biosecurity in Australia is arguably one of the most significant initiatives. While biosecurity is primarily focussed on safeguarding the country from unwanted pests and diseases of agricultural crops, there is no doubt that native biodiversity is benefitting from the stringent measures that are in place at all major ports of entry to the country. Excellent programs also exist at state level. For example, the NSW Saving our Species program is one of the biggest commitments ever undertaken by any state to conserve native biodiversity. The program involves various expert and stakeholder groups and aims to secure the future of threatened species in the wild and to control/manage the key threats they face. For example, as a ‘climate-ready’ strategy, Saving our Species coordinates the translocation of threatened plants to areas outside their current distributions that will have suitable climate conditions in the future. Similar programs have saved many of Australia’s mammals from certain extinction through captive breeding programs and translocations to predator-free islands.


What are some of the insights you have gained as a result of your research?


My own research is focussed on invasive species biology and plant ecology. I have learned that the impacts of invasive species can be highly complex and, importantly, context-dependent. This means that, while negative impacts on biodiversity by invasive species will always be evident, it is almost impossible to predict the types of impacts that will manifest. My research has also found current rates of plant extinction to conform to the so-called ‘sixth mass extinction,’ akin to the sudden disappearance of dinosaurs. While extinction has occurred throughout Earth’s history, we showed that, over the last 300 years, plants have been going extinct up to 350 times faster than historical rates. These estimates are likely to be gross underestimates and I am certain that we will witness the loss of a significant number of plant species in the near future.


Is there anything you would like to add or that you would like readers to know in regards to this issue’s theme of Extinction?


Be amazed by the variety and splendour of all things living. Without this biodiversity humanity cannot exist. The air that we breathe, the water we drink and the food that we eat, all depend on healthy ecosystems, and therefore biodiversity.

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