Since the break-up of Gondwana, Australia's biodiversity has evolved mostly in isolation from the rest of the world. Many of our species are unique to Australia.
But our biodiversity is at risk from alien invasive species. At least 100 unique native species have become extinct since European settlement, with more than three quarters due wholly or partly to invasive species. More than 1,250 of our land-based threatened species are at risk from introduced aliens, including weeds, insects and birds.
Let's take a look at some of the alien invasive species in Australia and how our science is addressing these invaders.
Sea spurge
Sea spurge, Euphorbia paralias, is a major plant invader of our beautiful beaches across Australia's southern coastline. It out-competes native plants and disrupts natural patterns of sand movement. It also reduces suitable nesting sites for native shorebirds.
The seeds of sea spurge are carried by ocean currents from infested beaches to new beaches, where they can quickly grow and dominate.
We're tackling this alien invader with a biocontrol fungus, Venturia paralias. We've thoroughly tested this natural enemy of sea spurge, a native of France, to make sure it's highly specific to sea spurge.
Sea spurge infestation at Darby River. Sea spurge grows along Australia's southern coastline. Credit: CSIRO
Bitou bush (Chrysanthemoides monilifera subspecies rotundata) is a weed targeted for eradication in Western Australia. The flowers are bright yellow daisies. Credit: CSIRO