Wetland Wildlife 5: Activities


Activity 1. Constructing food webs

Divide into eight groups. Using various references, each group constructs a food web with one of the following animals as a focal point of the web:

intermediate egret, Ardea intermedia                         water rat,Hydromys chrysogaster

northern snake-necked turtle, Chelodina rugosa        fawn antechinus, Antechinus bellus

sooty grunter, Hephaestus fuliginosus                       freshwater crocodile, Crocodylus johnstoni

Merten's water monitor,Varanus mertensi                rufous night heron, Nycticorax caledonicus

Try to find out the names of individual species, e.g. the snake-necked turtle eats fish, but what species of fish? Supplement your web diagram with notes about the status (common or not), distribution, and seasonal variations in population numbers of some of the animals in the web. Discuss in what form your work can be presented to the rest of the class.

Activity 2. Potentially vulnerable or vulnerable bird species

The eastern grass owl, the grey falcon, the peregrine falcon and the red goshawk are four birds of prey that are near the top of food pyramids. Select one of these birds and gather information about the bird's appearance, habitat, and food preferences. Record these details and find out why the bird has been declared a vulnerable or potentially vulnerable species and explain what these terms mean. What existing conservation programs may be assisting in protecting these species? Share the information with other students in the class.

Activity 3. Constructing a food pyramid

The insecticide DDT (dichloro-diphenyl-trichloroethane) was once commonly used but it remained in the plants or animals that had taken it into their systems and was passed along the food chains. The DDT was washed off the farmlands and into river systems where plankton (microscopic plants and animals) absorbed it. Small fish ate the macroinvertebrates that depended on the plankton for food, and larger fish ate the small fish. Ospreys, a type of fish-eating eagle, nearly became extinct because the accumulated DDT weakened the ospreys' eggshells and fewer birds were being hatched. DDT was banned and the osprey populations have recovered in numbers. Make a food pyramid illustrating the above story.

Activity 4. Aquatic plants: structure and habit

This illustration shows the structure and habit of different types of water plants. In small groups discuss the advantages to the aquatic ecosystem of having different habits of growth. Consider the three dimensions of the habitat (shoreline, water depth, distance from shoreline), competition for light and effects of increasing depth. In what ways does the variety of plant structure and habit affect the distribution, or spacing, of the plants? How does this affect the efficiency of the ecosystem? Support your group's answer with a perspective diagram (i.e. showing three dimensions) and explanatory notes.

Activity 5. Riparian habitats

The riparian zone links the catchment area with the river system. Falling leaves, fruit and other organic debris provide direct inputs of nutrients and energy to the rivers, streams and billabongs. Algae and bacteria break down much of the plant material, but some is taken directly by animals living in the stream e.g. pandanus seeds being eaten by sooty grunters. Insects falling from the foliage provide a food source for fish and the archer fish is especially adapted to hunt for insects clinging to overhanging branches.

Trees provide shade and reduce water temperatures, keeping the growth of algae in check and allowing a higher amount of dissolved oxygen to be available to plants. Logs and branches falling into the water create important habitats for small fish and invertebrates. The debris also slows down the movement of organic matter through the stream. Plant growth along the banks of watercourses not only slows down erosion but catches and holds debris carried by the water.

Working in small groups, construct a poster in the form of a pictorial diagram illustrating as many as possible of the riparian habitat features mentioned above. Use caption boxes and arrows to explain what is happening in your poster. Simple symbols or cutout photocopies of plants and animals may be used for the pictorial elements of the poster.

Activity 6. Wetlands plants: video viewing

Obtain the NT Department of Education videotape, Window on the Territory No 5. View the two segments River Flood Plains and Freshwater Habitats and note how many different types of plant life are included.

Activity 7. Plant-animal relations

Construct a table that summarises the relations between wetlands plants and the animals of the wetlands. List the animals or groups of animals that are mentioned in the text and make columns for plant, and type of relationship.

Activity 8. Insect conservation

There is a convincing case for recognising the importance of insects in conservation management programs, but how can this be brought about? It is impossible to make an insect reserve by simply fencing off an area of wetlands and besides, how do we know what type (and what number) of insects we are dealing with?

Compose a 1000 word action plan for the conservation of insect life in Top End wetlands using some of the key concept words below. Your teacher may want you to work in groups on this activity.


research                        long-term                       awareness                       habitat preference

life cycles                       integrity                          monitoring                      environmental factors

integrated                       pollution                         water quality                   indicators

management                   interrelated                     zones                              energy paths

Activity 9. Report on an aquatic invertebrate

Select one of the groups of aquatic insects or other invertebrates mentioned above and research its life history, identifying features (size etc), adaptation to an aquatic environment, and place in an aquatic food web. Write a report using those aspects as a reference framework.

The results of your research may be gathered in the form of a clip file containing data from a variety of sources, but the life history, adaptive features and place in the food web should be your own original work, whether in written or in pictorial/ diagrammatic form.

Activity 10. Adaptations

Animals have three main ways in which they are adapted to their environments: behaviour, structure and function.

There are many forms of behaviour: a yabby hiding under a log, a small fish joining hundreds of others in a school, a magpie goose building its nest when the water is at the right height, an egret stirring up the mud with its feet to flush out small aquatic animals and a water scorpion flying away from a drying pool are all examples of behavioural adaptation. The animal goes into a set course of action or behaviour that will most assist it in its survival.

All animals have an anatomy (structure) that allow them to survive in their environments. The design features such as body shape, legs, fins, wings, body coverings, beaks, claws, breathing tubes, stings and sensory organs are the end products of millions of years of natural selection. Those animals (individuals or species) that didn't have the right structure and design details to suit a certain type of habitat, or particular behavioural adaptations, just ceased to exist.

The way in which an animal's body works or functions is called its physiology. The functioning of the various systems (digestive, nervous, reproductive, respiratory etc) are closely related to an organism's environment e.g. the gills of a fish can extract oxygen from water whilst our lungs can only extract oxygen from the air.

Analyse the adaptations shown by frogs of the Top End. Identify the adaptations mentioned in the text and sort them out under the three major headings given above. Describe each adaptation and comment on whether you consider it to be an adaptation that applies to all frogs generally, or whether it is suited specifically to Top End conditions.

Activity 11. Interactions

In the illustration of a Top End billabong, there are a number of organisms typical of the region. Think of some possible interactions that could exist in this habitat between the plants and animals shown. List your ideas under these headings: SHELTER, FOOD CHAINS, COMPETITION, SPATIAL SEPARATION

Activity 12. Environmental factors

Obtain the mean monthly rainfall figures and the mean monthly maximum and minimum temperatures for a Top End locality (Darwin or Jabiru). Present them in graph form and consider the effects of the data you have gathered on the living things of the region. In what ways could the conditions you have charted affect the plants and animals of the billabong? Give five or six examples for individual plants or animals. Consider both direct and indirect effects of climate.

For example: First rains of the wet season make wild rice grow; triggered by both timing and amount of rainfall; these in turn are part of the monsoonal weather cycle; seeds develop just as young magpie geese hatch out in late wet; provide a handy on-the-spot food source for goslings.

Activity 13. Biodiversity and its value

As a major individual assignment, carry out research into the value of biodiversity and select one of the major values to comment upon: ecosystem services, biological resources, or social benefits. Say in what ways the values of biodiversity and its components can affect wetlands as a whole and comment upon the implications for human interactions with wetlands.

Reading:DEST. (1996). Biodiversity and its value. Canberra ACT: Department of the Environment, Sport and Territories, Biodiversity Series, Paper No 1.

Activity 14. Biodiversity and food-gathering adaptations

Biodiversity allows resources within the one habitat to be fully exploited. To gain an understanding of what this means, form small groups and discuss the different shapes of the beaks belonging to the waterbirds shown in Figure 8. Research the birds shown and discover their main food preferences. Make a table showing the birds' names, their main foods and comment on how the shape or size of each bird's beak helps it to gain food. (This activity can be repeated using the shape/size of birds' legs).

Look for a main connecting idea in the information you have gathered and comment on the possible effects/ advantages of biodiversity.   

1. Energy flow 2. Plants of the wetlands 3. Animals of the wetlands 4. Biological diversity  

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Did you know?

Amphibians were the first backboned animals to emerge onto land. Far older than the dinosaurs they have evolved many strage survival strategies.