Issue: Pressures on biodiversity - Invasive species
This is an issue under the Biodiversity theme of the Data Reporting System.
An invasive species is a species occurring, usually as a result of human activities, beyond its accepted normal population or distribution, and which has a potentially negative impact on the resident ecosystem. Even species endemic to an area can become invasive as a result of changes in environmental conditions which favour them over another species. More often, invasiveness occurs when new species are intentionally or accidentally introduced to an environment by human action, becoming naturalised and thriving in that environment to the potential detriment of other species. This is most likely to occur in environments that have been intentionally altered to favour introduced species, for example, for agriculture. Habitat modification, disturbance and destruction, including changed fire and water regimes, can cause changes in species distribution, favouring one species over another and leading to invasiveness by some species.
Alteration of an established number, population and distribution of species contributing to an ecosystem can result in a reduction in overall species abundance and diversity. Niches once occupied by a range of species can be taken over by a particularly successful species. As a result, access to available food or shelter may be reduced for less successful species, and impacts on one species can then affect other species that may be dependent on the diminished species.
Invasive species can include diseases, fungi and parasites, terrestrial and marine animals (including insects and other invertebrates) and plants and can place pressure on terrestrial, marine and freshwater biodiversity.
- IW-37 Examples of carp pressures and measures for removal and/or commercial catch
Carp have the potential to be invasive in some environments. Examples of pressures from carp, along with either positive or negative changes in these pressures where control or harvesting measures are taken may provide insights into the actual impacts of the animal and the effectiveness of responses.
- IW-38 Cane toad distribution
In 1935 cane toads were released throughout cane growing areas in Queensland to control cane beetles. They did not control the beetles but ate large numbers of beneficial insects.
The cane toad has a large gland behind the head that can exude a poisonous milky substance when the toads are disturbed. Cane toad poison is highly toxic to many animals. The eggs and tadpoles of toads are also poisonous. Predators are vulnerable to the toads. Since introduction the cane has increased its distribution. Changes in the extent of its distribution provides some indication of the area where the species could become invasive.
- IW-39 Examples of significant wetland weeds
In the absence of detailed data on the distribution and actual impact of various wetlands weeds, examples of how particular weeds can affect aquatic and terrestrial biodiversity are worthy of consideration.
- BD-09 The change in extent of selected nationally significant 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
- BD-10 Examples of native species whose populations have declined where various invasive species have established resident populations
A spatial correlation between declines in native species and establishment of introduced populations does not automatically imply a cause and effect relationship, especially where there are other pressures, such as habitat modification, which could be the common cause of both changes. However, compiling data on such correlations may enable the development of studies which control for other pressures and thus provide insight into the actual impact of naturalised species.
- LD-19 Land use and land use change
While the term “invasive” is usually used to refer to introduced species that have become naturalised in the wild, in terms of scale of impact, the invasive impact of plants and animals intentionally introduced and maintained for agriculture is much more significant.
- LD-20 Total grazing pressure relative to net primary productivity
While the term “invasive” is usually used to refer to introduced species of plant and animal that have become naturalised in the wild, in terms of scale of impact, the invasive impact of introduced plants and animals utilised in agriculture, and especially introduced grazing animals and introduced pasture for them to graze on, is much more significant.
- LD-35 Temporal and spatial correlation between changing fire regimes and species change
Changing fire regimes can alter the populations and distribution of species, and lead to invasiveness by native or introduced species that are favoured by the changes.
- LD-40 Current research into pressures and contributions of naturalised introduced species
Other indicators for this issue do not indicate whether naturalised populations are exerting pressure on native species or ecosystems, or the extent of that pressure. Current research into this issue, even in the absence of national data, may shed some light on these effects.
- BD-13 Examples of the impact of grazing on biodiversity
While the term “invasive” is usually used to refer to introduced species of plant and animal that have become naturalised in a wild state, in terms of scale of impact, the invasive impact of introduced plants and animals utilised in agriculture, and especially introduced grazing animals and introduced pasture for them to graze on, is much more significant.
- Land - Direct pressure of human activities on the land - Species introduction and species change
- Inland Waters - Human response - policy and management - Management of aquatic biota and biodiversity
- Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Direct pressure of shipping