Frogs - Conservation

Background

Australia has a fascinating and spectacular variety of frogs, over 210 of the world’s ~5,000 species. The majority of Australian frogs are unique due to Australia’s long isolation. The origin of Australia’s frog fauna can be traced back many millions of years when Australia formed part of a large landmass called Gondwana.

Victoria has at least 35 species, all of which belong to one of two frog families; tree frogs (Hylidae) and the ground or marsh frogs (Myobatrachidae). In Victoria, a number of frog species have declined or are currently in decline. The Baw Baw Frog was once common on Mt Baw Baw around the ski resort however have now disappeared completely from the mountain. Similarly, the now endangered Growling Grass Frog was once common around parts of Melbourne.

Some declining species e.g. the Southern Barred Frog and the Booroolong Frog are at the limit of their range in Victoria. Very small changes in climate or habitat could make the environment unsuitable for these species and result in their extinction in Victoria. Species such as the Spotted Tree Frog have disappeared from much of their habitat. Predation from introduced trout, increasing sediment loads from stream disturbances and disease appear to be contributing factors.

Introduced predators including cats and foxes may reduce frog numbers while the spread of introduced fish like trout and mosquito fish can destroy tadpole populations. Use of pesticides and herbicides can lead to frog declines causing respiratory problems and abnormalities in frogs, tadpoles and embryos.

Increasingly, communities are becoming involved in a number of conservation projects – recording frogs in the local area by conducting surveys, joining frog/field naturalist groups and creating ‘frog friendly’ gardens and reserves. Creating suitable habitat and allowing local frogs to move in naturally to colonize this habitat is one of the best ways to increase your local frog population.

Aim

The aim of this session is to:

Investigate some of the reasons for frog decline using an interactive web-based program
Prepare an electronic report providing evidence to support your findings.

Materials

Access to computers and the internet
Coloured pencils
Growling Grass Frog website http://frogs.org.au/frogs/species/Litoria/raniformis/
Environmental evaluation report – frog pond habitat website http://frogs.org.au/frogs/species/Litoria/raniformis/
Growling Grass Frog Action Statement http://www.dse.vic.gov.au/DSE/nrenpa.nsf/LinkView/69770772A2A1F48BCA256F...

Notes for teachers

This activity requires internet access for students to the above websites.
The introductory activity involves students identifying the Ecolinc logo as a frog (Growling Grass Frog) and investigating reasons why a frog is a suitable logo for Ecolinc – frogs are good environmental indicators.
Students record some key information relating to the Growling Grass Frog using the Growling Grass Frog website.
Students then examine the causes of decline in a frog population using an interactive web-based program simulating a frog pond habitat.

As part of the program students will:

analyse the water quality of a pond by testing dissolved oxygen, pH, temperature and total phosphorus on-line
build a food web to examine the relationships between the living things in the habitat
examine the predator/prey relationships for the life cycles of the frog, tadpoles and frog eggs
examine data and determine the major cause of decline in a frog population
construct an environmental evaluation report, by examining the data presented and detailing the major cause of decline in a frog population.

Finally students will examine the current DSE Draft Flora and Fauna Guarantee Action Statement for the Growling Grass frog from the DSE web site and list some of the appropriate management strategies which could be used to conserve a frog population in a frog pond habitat.