>Students gain an understanding of the various forms of underwater habitat and the wildlife that make use of them
>Students learn about human induced impacts on river habitats and their associated plants and animals
>Aquatic animal cards (see below)
>Benthic macroinvertebrate poster (can be obtained from a local Catchment Management Authority or state natural resource management agency)
>In-stream habitat scenarios (see below)
>Homework sheet – Match the species activity sheet (see below)
It is important to understand the nature and quality of underwater (in-stream) habitats, because these are a major factor determining the types, distribution and abundance of aquatic wildlife such as fish, platypus and invertebrates. Other factors include flow patterns, water quality, food supply, run-off and impacts from the riverbank and floodplain, competition between species for space and food and predation.
Not all streams provide the same types of habitats. The type and number of microhabitats vary naturally between and along streams. Major differences are apparent when
Old trees creating snags like this provide vital habitat for native fish. Photograph: Bill Phillips
rivers at higher elevations are compared with those lower down. Rivers with rocky substrate and fast flowing through confined spaces have very different fauna to those that meander and wind across flat, open floodplains.
In the absence of suitable habitat very few species will be found even in waterways with good flow and excellent water quality. Generally the greater the variety of habitats in a waterway the greater the number of species found.
The different habitats provided by mud, cobble stones, woody debris (snags), rocks, and submerged and floating plants are readily used by a range of aquatic life for shelter, rest and feeding.
Unnatural inputs to the river (such as farm or urban pollution or sediment from soil erosion) and waterway interferences (like straightening, de-snagging, dam construction and water diversions) can significantly degrade in-stream habitats.
Rivers contain a range of habitat types for aquatic wildlife. The following are among the most common:
>leaf litter and small woody debris
>large woody debris and fallen trees (snags)
>pools, runs, riffles, rapids, cascades and waterfalls
>sand, mud, pebble, cobble, boulder and bedrock substrates
>edge and in-stream reeds and rushes.
Namoi River near Boggabri, NSW, during dry times, but highlighting the complex underwater habitat of pools and snags when the river has more water. Photograph: Milly Hobson, I&I NSW
1. Using the Benthic Macroinvertebrate Poster review with the students the riffles, runs and glide habitats (see Glossary if necessary).
You can do this activity
i the classroom using
the poster or down at
a local river or stream.
2. Point out other aspects of in-stream habitat such as submerged wood (snags), pebble, mud or cobble stream bottoms, and reeds and rushes growing in the water.
3. Ask students to speculate on what these microhabitats might offer aquatic wildlife.
4. Give each student an aquatic animal card (see below). Ask them to familiarise themselves with the needs of their animal (as given on each card) and draw the animal on the card.
5. Ask the students to stand in a circle or at their desks. Read out or distribute In-Stream Habitat Scenario 1 (see below). Get the students to sit if they think the habitat needs of their animal have not been met.
6. Review which animals are still alive and which are not. Write ‘Scenario 1’ on the board (or notepad for further review back in the classroom) and list the survivors.
7. Repeat this process for In-stream Habitat Scenarios 2 and 3. Ask students what trends they detect. How are the animals doing which have more general needs verses those with specific needs? What could be done to reverse the trends which are emerging?
8. Ask the students to create their own scenario for the Return of the River’. What would they do to bring back the animals that have been lost?