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9.5 Option- Introduced Species and the Australian Environment: 4. Case study on an introduced species

Syllabus reference (October 2002)
4. Development of a case study on an introduced species that has had an impact on the physical and/or biological environment	*Students learn to:* summarise for the above named introduced plant and animal: the history of introduction the environmental conditions leading to the organism becoming a pest dispersal techniques reproductive capacity evaluate for the above named introduced plant and animal: the impact on the physical environment control strategies	*Students:* analyse information from first-hand and/or secondary sources and use available evidence to assess the environmental impacts of named plant and animal gather and analyse information from secondary sources to determine the relative merits of different possible control strategies for the named plant and animal

Extract from Earth and Environmental Science Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.
[Edit 6Aug08]

Prior Learning: Science Stages 4–5 syllabus: Outcomes 5.10 (content 5.10c).

Preliminary Course 8.3 (subsection 5). 8.4 (subsections 1)

summarise for the above named introduced plant and animal:

the history of introduction
the environmental conditions leading to the organism becoming a pest
dispersal techniques
reproductive capacity

Using case studies in section 9.5.3 create your own case studies for one introduced plant andone introduced animal. An animal that could be used is either:

rabbit or
cane toad

A plant that could be used is either:

Lantana sp
Salvinia sp

Your case study should summarise information under the headings shown above.

Make sure you list all references used in your research.

analyse information from first-hand and/or secondary sources and use available evidence to assess the environmental impacts of named plant and animal

Critically assess the environmental impacts of the species giving them a rank from most damaging to least damaging.

You may not consider it possible to do so given that they invade various parts of the environment. In that case, give them a description that may help you assess the impact.

evaluate for the above named introduced plant and animal:

the impact on the physical environment
control strategies

The last section of each case study in 9.5.3 has an analysis of the impact.

gather and analyse information from secondary sources to determine the relative merits of different possible control strategies for the named plant and animal

Gather information from the previous section and extend this information from other sources if you think what you have isn’t adequate.
Control strategies for rabbits

Climate, predators and parasites have had minimal impact on numbers. Conventional methods include exclusion fencing, ripping of warrens, fumigation of warrens and poisoning.

Diseases such as myxomatosis and Rabbit Calicivirus Disease have been introduced into populations. At first over 90% of the rabbits died but the ones that had resistance passed this on to their offspring and now only 60% of rabbits that contract Myxomatosis die. Myxomatosis requires an insect vector and as such is limited by the range of the insect. A Spanish flea has recently been introduced into the rabbit population to carry the disease into the arid regions of South Australia.
Control strategies for cane toads

None at this stage.

Viruses found in Venezuela kill tadpoles of toads but also native species. Two fungal pathogens have been discovered but more research is needed.

Since 2001 CSIRO has been conducting research into developing a biological control for cane toads. The goal of the research is to interfere with the metamorphosis of the cane toad to prevent it from maturing and reproducing.

The control strategies section of each of the Case Studies in 9.5.3 has information you can analyse to determine the relative merits of different control strategies.
Control strategies for Lantana

Chemical control by a herbicide such as glyphosate (Roundup) is effective as burning, slashing and digging results in greater numbers growing back.However a second treatment is often required to be fully effective. “Find native plants which can compete with it and produce a shade canopy to reduce it from spreading.” Dr Duggin, University of New England.
Control strategies for salvinia

Successfully controlled by a small weevil (Cyrtobagus Singularis) since 1980 in northern Australia. In Mt Isa the local water supply, Lake Moondarra was inundated with the weed. Once the weevil was introduced, 50 000 tonnes of the weed were consumed in ten months. The weevil has not been very effective in the southern states. Herbicides and mechanical removal have been used in parts of NSW.

Analyse the strategies listed above to consider their effectiveness.