4.3 Plant and animal invaders
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Curriculum Alignment

1, 2, 14, 18, 19

Years K-6: Science and Technology, HSIE, Mathematics
Years 7-10: Agriculture, Science, Mathematics 
Years 11-12: Agriculture, Geography, Biology, Earth and Environmental Science, Society and Culture

SOSE, Science, Geography

Futures, Interdependence, Thinking

Science, Thinking Processes, Geography

>Students will learn to identify native and exotic plant and animal species through a local investigation
>Students will gain experience in interpreting graphs and maps in identifying concentrations of native and non-native species
>Students will gain an understanding of the impacts of introduced species on natural ecosystems

2-3 hours

Materials required
>Writing materials to create a report and graph or pie chart
>Field guides and plant and animal identification reference materials for your region (your local Catchment Management Authority or natural resource management agency should be able to help)
>Tape measures
>String to mark plots
>Dominant species recording sheet (see below)
>Homework sheet – Invasive or not? (see below)

An invasive species is one occurring, usually as a result of human activities, beyond its accepted normal distribution and which threatens valued environmental, agricultural or other social resources.

Invasive species have had, and are continuing to have, a major impact on Australia’s environment, threatening our wildlife and impacting on a wide range of ecosystems, including waterways.

(Top) Carp stranded when the Lachlan River was closed and Lake Cargelligo dried out in early 2010. Photographer: unknown. (Bottom) One of our most prolific plant invaders, willows. Photograph: Bill Phillips.
(Top) Carp stranded when the Lachlan River was closed and Lake Cargelligo dried out in early 2010. Photographer: unknown. (Bottom) One of our most prolific plant invaders, willows. Photograph: Bill Phillips.  

Introduced aquatic pests
Introduced freshwater fish species in Australia include Carp, Brown trout, Rainbow trout, Redfin perch, Mosquito fish (Gambusia), Oriental weatherloach and Spotted tilapia, to name a few.
Some introduced freshwater fish species have had a devastating impact on Australia’s native freshwater fish species and other native aquatic life. For example in much of south-eastern Australia’s freshwater systems Carp (often incorrectly called ‘European’ carp) dominate. The ability of carp to colonise almost any body of water is what makes them such a successful invader. While the damaging impact of Carp is well recognised, control measures will never eradicate the species now it is established. The best we can hope for is that numbers can be reduced such that native fish can start to rebuild their numbers. Reducing carp populations is now the focus of intensive research and this is starting to provide many new strategies to interfere with their breeding, to lure them to places where large numbers can be trapped and to intercept them as they move through fishways.

Redfin perch. Photograph: Gunther Schmida
Redfin perch. Photograph: Gunther Schmida

Mosquito fish (Gambusia). Photograph: Gunther Schmida
Mosquito fish (Gambusia). Photograph: Gunther Schmida

Feral mammals
Australia’s native plants and animals adapted to life on an isolated continent over millions of years. Since European settlement they have had to compete with a range of introduced mammals for habitat, food and shelter. Some have also had to face new predators. These new pressures have also caused a major impact on our country’s soil and waterways and on its native plants and animals.

Feral animals impact on native species by predation, competition for food and shelter, destroying habitat, and by spreading diseases. Feral animals such as rabbits graze or degrade vegetation that provides food and shelter for native animals. Feral mammals can cause soil erosion. While managed domestic livestock can be removed from degraded areas (such as riverbanks and floodplains) until these areas are revegetated, it is much more difficult to keep feral animals out of these same areas.

There are a number of control methods available for feral animals. These methods include conventional control techniques and biological control. Conventional control methods for feral animals include trapping, baiting, fencing and shooting. 

Invasive weeds are among the most serious threats to Australia’s natural environment and primary production industries. They displace native species, contribute significantly to land degradation, and reduce farm and

If you'd like more
information and suggestions
for lessons focussed on 
carp, visit FeralFocus, go
to Unit 3 and follow the link
'The problem with carp'.

forest productivity. Australia spends considerable time and money each year in combating weed problems and protecting ecosystems and primary production on private and public lands. 
Along the waterways of the Murray-Darling Basin perhaps the most common weed species are willows and blackberries. There are many different species of willows that have been introduced into Australia, some being more ‘invasive’ and damaging to waterways than others.

Diseases, fungi and parasites
Invasive diseases, fungi and parasites in Australia affect many native plants and animals and agricultural crops. Some diseases have contributed to significant losses of species leading to some becoming threatened or extinct. Among those of concern for aquatic species is the Chytrid amphibian fungus (Chytridiomycosis) (see Module 1.3 in Part 1).

Diseases, fungi and parasites can affect the health of native species, reducing their ability to reproduce or survive. Threatened species with reduced and restricted populations due to other factors are particularly vulnerable to outbreaks caused by these introduced organisms. 

Non-native species
Introduced species
Native species
Dominant species

Lesson plan
Before the activity
1. Visit the portion of the river, stream or wetland you plan to work with and identify the six most common introduced and native species. 

2. Explain to students before they go to the site that they will be identifying plants along the river. Demonstrate the use of the field guides, focusing students on leaf shapes, arrangements, buds and seed heads. 

3. Describe or show examples of the six local target introduced and native species. (These may be plants or animals).

It will also be helpful
to record any large tree
within the plot, even if it
is not one of the four
dominant species. There might
be less of them but they
are still important!

In the field
1. Divide the class into groups of 3-4 students. Explain that each group will be working in a designated plot. A three by three metre plot is ideal, with one adult assistant per plot for younger students. The plot of each group should border the next so the result is one large, contiguous plot being surveyed.

2. Give each group a copy of the Dominant Species Recording Sheet (see below). Review the categories with the students. Students should describe at least three identifying CHARACTERISTICS of each plant or animal they find. In the REMARKS area, students should note where the organism was found, its health, age or anything unusual about the population.

3. With the aid of field guides, all groups will identify the four dominant species in their plot. In this situation, dominance is based upon which species is the most numerous. Make sure the students also record any of the target introduced species found. 

In addition, make sure students do not assume that just because a plant is not one of the target introduced species, that it is native! If students encounter other dominant introduced species in their plot, they should refer to their field guides.

4. If there are too many individuals of one species to count, show the students how to estimate the number by counting the individuals in a one square metre subplot, and then extrapolating for the total area. A section at the bottom of the Dominant Species Chart is provided to compute the percentage of the identified individuals that were native and non-native.

5. While students are identifying the species in their plots, have them draw the major features of their sites and include the locations and names of the plants they found on the back of the sheet. Have them include any feature that could affect the health or make-up of the site.

Analysing the data in the classroom
1. Students may analyse the data from each group or from the class as a whole by developing pie charts and vegetation maps.
Pie Charts: Each group calculates the percentage of the introduced and native species. Combine data from all the groups to develop a classroom pie chart.
Vegetation Maps: The groups combine their plot diagrams showing the locations and identities of plant species. Group members will need to agree on what symbol represents each species.

Carp have invaded most of the rivers, streams and wetlands of the Murray-Darling Basin. They can grow to very large sizes! Photo: copyright The Federal Capital Press Pty Ltd.

2. Have students conduct research on the introduced species found. Ask them to write short reports explaining how the introduced species arrived here, what positive and negative impacts they have had on the environment and wildlife, and what management techniques are, or have been used to control their populations.

3. Ask students to share the findings from their research with the class. Compare the role of wildlife managers and community members. How do community members contribute to the dispersal of introduced species? What can community members do to limit dispersal? Ask the students to reflect on the importance of habitat evaluation in managing introduced species.

Establish with the Catchment Management Authority, natural resource management (or similar body), local council or landholders some long term control plots for the activity. 
Establish two plots, three meters square. Leave one plot as the control, and let it develop without disturbances. 
For the second plot, try a management technique such as hand removal of all non-native plant species. 
This long term project demonstrates how ecosystems change over years. Have classes observe the plots over several years and record, draw or photograph the changes.

Secondary Pathway
With GPS or Google Earth, and GIS mapping programs (if available), have students survey and map native plant communities along their local river reach.

See Invasive or not? worksheet.

Feral Focus Feral Focus