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Macroinvertebrates (bugs)
(Adapted from The Streamwatch Manual – 3rd Edition)
Definition
Aquatic macroinvertebrates are animals that have no backbone, are visible with the naked eye and spend all or part of their life in water. Aquatic macroinvertebrates are a very diverse group of animals that include worms, molluscs, arachnids, crustaceans and insects.
Why test aquatic macroinvertebrates?
Aquatic macroinvertebrates are excellent indicators of water quality and ecosystem health. This is because:
- They spend most or all of their lives in the water
- they are an important part of the aquatic food chain and therefore the creek or river ecosystem
- different species have varying sensitivities to pollution.
Equipment
- Sorting trays
- Scooping sieves or nets
- Large scoop net or pool net
- White ice cream containers
- Aquatic macroinvertebrate identification book
- Streamwatch Pollution Index Sheet
- Macroinvertebrate Recording Sheet
Method
1. Select a 20 metre stretch of the creek to be sampled.
2. Half fill the sorting trays with creek water and place them on a level surface next to the creek.
3. Spend a few minutes looking around the site and record the different habitats present on the recording sheet.
4. Sample in the different habitats present, placing the macroinvertebrates into white ice cream containers.
- Use scooping sieves or nets to collect macroinvertebrates along the edges of the creek and in riffles.
- Use the large scoop nets and pool net to collect macroinvertebrates from the pools.
- Collect leaf litter from four or five locations along the sample site.
- Collect rocks and carefully scrape off the macroinvertebrates into the ice cream containers.
5. Empty the contents of the ice cream containers gradually into the sorting tray.
6. Identify the aquatic macroinvertebrates using the aquatic macroinvertebrate identification book.
7. After the aquatic macroinvertebrates survey has been completed, the stream pollution index can be calculated and recorded.
Updated: 04 Jan 2012