Invasive Species

What is an Invasive Species? A species that has been introduced or is not native to an environment Invasive species are generally harmful to the local habitat or native species Unwanted pest Not all non-native organisms are invasive

More Examples of Invasive Species Grey squirrel American beaver Cane toad

Different Routes of Invasion Most invasions are due to human activities: Plant or pet trade Commercial shipping Tourism …and many other routes…

Quiz: What Characteristics Make A Good Invader? Rapid reproduction Fast growth High dispersal Tolerant to many different conditions Able to live off many different foods Used by humans

The Impact of Invasive Species Ecological: –Reduce native biodiversity –Direct predation on local species –Spread of disease –Upset balance of local ecosystem

The Impact of Invasive Species Economical: - Very expensive - agricultural pests cause millions of dollars of damage every year! - Very expensive to eradicate invasive species

Controlling Invasive Species Controlling invasive species once they have become established is difficult. Control is also usually very expensive! There are four main ways that invasive species are controlled: –Physical control –Chemical control –Biological control –Prevention

Physical Control of Invasive Species Controlling plants: Mechanical – excavation, strimming, etc. Removal of plants by hand Installation of growth barriers Controlling animals: Culling Trapping and hunting Putting up barriers or fences

Chemical Control of Invasive Species Chemical control involves applying poison to eliminate invasive species E.g. Eradication of rats on Henderson Island –Use rodenticide (rat poison) Insecticides & pesticides to control insect pests Herbicides (weed-killer) to control plants

Biological Control of Invasive Species Uses a living organism to control invasive species This organism may eat the invasive species or cause it to become diseased Biological control agents must be carefully assessed before release to ensure the control species will not become invasive itself Seven-spot ladybirdHarlequin ladybird

Preventing Invasive Species Prevention is better than cure! Preventing invasive species from being introduced somewhere in the first place, or preventing them from spreading if they do arrive, is the key to avoiding long-term harm to ecosystems

Barrow Island Case Study Barrow Island is a small island off the NW coast of Australia that is home to many species that have become rare or extinct on the Australian mainland This is partly due to a rigorous Quarantine Management System (QMS) operated by Chevron, which prevents invasive species from becoming established on the island