Gould League - Food Webs - Secondary Activities

Food webs, Classification and Biodiversity

Additional secondary activities to accompany the Gould League Food webs, Classification and Biodiversity kit.

Food webs in a pond

Level: 5 & 6
Curriculum Area: Science

Outcomes

Students:

Explore food chains and food webs in a pond
Identify common creatures found in ponds

Materials and Preparation

Ponding reference material such as Gould League publications - Australian Guide to Pondlife, Freshwater invertebrates, Wetlands wildlife. Pondlife poster. Ponding equipment such as ponding nets, large white trays, large screw top jars as temporary storage. A video flex microscope would be useful as students (and teachers) find it fascinating watching wetland creatures under high magnification.

Method

Plan a ponding excursion. Prior to the excursion spend a lesson looking at ponding books and resources to familiarise the students with common creatures they may find.

These include: tadpoles,fish , mites, wrigglers (mosquito larvae), leeches, water striders, back swimmers, water boatmen, mayfly larvae, caddisfly larvae, mudeyes (dragonfly larvae), snails and algae.

Generate a list that sorts the animals into carnivores, herbivores, producers and scavengers. Make sure bacteria and birds such as ducks and herons are included. Also discuss a code of conduct at the ponding venue. Students should understand that pond animals should be handled gently and must be returned to their environment once students have finished observing them.

At the ponding venue students should work in pairs. Each pair should have a tray filled with pond water. Students should sweep their nets gently through the water and then immerse the net inside out in the tray to release any creatures or pond plants that may have been caught.

Students should identify the pond animals and plants and count them to see which are most abundant and which are less common. Use reference books to find what these creatures feed on. Try and build-up food chains and then food webs from the plants and animals the class has collected.

Guide a class discussion about food chains and food webs in wetlands and ponds. Use the following scenarios:

Imagine that a herbicide has been accidentally released into local water ways that kills all water plants. What animals would be affected?
Imagine that a mass release of phosphate into waterways causes a massive algal bloom. Ask students to find out about algal blooms and discuss the consequences for food webs. Students could refer to the Internet for information.
Why do herons and pelicans fly to many ponds to feed?

Extension

If the school has or can hire a video flex microscope, store some of the pond animals in jars and return to the classroom to observe them. Avoid keeping the pond creatures for more than 12 hours and make sure they are returned to the wetland/pond where they were first collected.