Indicator: BD-09 The change in extent of selected nationally significant invasive species

Data

Naturalised terrestrial and freshwater animal species

Over 80 species of exotic vertebrates (excluding marine species) have established wild populations in Australia. These species include:

  • 25 mammals;
  • 20 birds;
  • 4 reptiles;
  • 1 amphibian; and
  • 23 freshwater fish on mainland Australia;
  • plus 1 mammal, 7 birds and 2 reptiles on offshore islands

Percentage of records that are introduced species

Percentage of records that are introduced species

Source: National Land and Water Resources Audit 2002, Australian Terrestrial Biodiversity Assessment 2002 - Birds, viewed 11 Jul 2006, http://audit.ea.gov.au/ANRA/vegetation/docs/biodiversity/bio_assess_birds.cfm.

Naturalised terrestrial plant species

Over 28 000 foreign plants have been introduced to Australia and over 2 500 species have established in the wild, and may threaten the integrity of valued places, such as Kakadu National Park.

The per cent of Australia occupied by each of the top 20 weeds
Weed Percent
Bitou bush 3
Blackberry 9
Gorse 3
Lantana 5.1
Mimosa 1
Parkinsonia 12.4
Parthenium 5.6
Prickly acacia 2.3
Rubber vine 7.7
Serrated tussock 2.2
Willows 0.8
Alligator weed 0.4
Athel pine 1
Bridal creeper 5
Cabomba 0.5
Chilean needle grass 0.2
Hymenachne 1
Mesquite 5.3
Pond apple 0.4
Salvinia 5

Source: Sinden, S Jones, R Hester, S Odom, D Kalisch, C James, R and Cacho, O 2004, 'The economic impact of weeds in Australia', in, (ed), Technical series No. 8, CRC for Australian Weed Management, Glen Osmond, SA.

What the data mean

While there are data on the current distribution of a number of introduced species that are perceived to be invasive, there are at present virtually no data on changes in distribution which might alert the community either to an increased risk that an introduced species may be becoming invasive, nor to any increase in area under threat from a species that is perceived to be invasive.

Data Limitations

The general distribution of many invasive species is easier to obtain than the actual numbers, density or rate of spread. Reporting on the full range of introduced wild species is resource intensive.

The indicator assumes that some species are invasive, and tracks their distribution. It sheds no light on whether or not they are, in fact, impacting invasively on the ecosystems in which they are naturalised, nor, if so, the extent of their invasiveness.

Issues for which this is an indicator and why

Biodiversity - Pressures on biodiversity - Invasive species 

Where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion

Other indicators for this issue:

Land - Direct pressure of human activities on the land - Species introduction and species change 

Modification of the terrestrial environment, whether for agriculture or urban development of any other human purpose, involves removing resident species and introducing new species. This intentional unbalancing of ecosystems can cause some species in the modified environment to become invasive. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be in the wide range of environments and ecological communities across Australia, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.

Other indicators for this issue:

Inland Waters - Response of biota - Invasive species 

Modification of freshwater environments for irrigation, extraction, storage, recreation, or any other human purpose, can involve removing resident species and introducing new species. This unbalancing of ecosystems can cause some species in the modified environment to become invasive. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.


Other indicators for this issue:

Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Pressure of fishing 

Species can be introduced to an ecosystem from fishing activities, especially, potentially, aquaculture. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.

Other indicators for this issue:

Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Direct pressures of harvesting non-living materials 

Species can be introduced to an ecosystem from exploration rigs. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.

Other indicators for this issue:

Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Direct pressure of coastal activities (other than shipping and fishing) 

Species can be introduced to an ecosystem by various types of coastal activities. While it is difficult, on the basis of any available data, to establish whether and how invasive any species might be, changes in distribution and population of one species may be an indicator of more profound ecological changes. Additionally, where there is a concern that a particular species is behaving invasively, changes in its distribution may signal an increase in area at risk, either from the species itself, or from the environmental modifications that are favouring its expansion.

Other indicators for this issue:

Further Information

National Introduced Marine Pest Information System

Weeds Australia’s WONS list

Weeds Aust noxious weeds database

Cane toads

Invasive Species

Australian Terrestrial Biodiversity Assessment 2002

  • Australian terrestrial biodiversity assessment 2002 

Review of Progress on Invasive Species

Senate document -Turning back the tide-the invasive species challenge