What are aquatic macroinvertebrates?
Aquatic macroinvertebrates are the little animals without backbones that live in just about every freshwater system in the world. If you find water without them - unless its been filtered for human consumption- then it's pretty likely that something is seriously wrong with the water. Invertebrates make up more than 99% of the animals on planet earth... that's right; there are a whole lot of bugs out there!

Why are these little critters important to us?
For the answer to this question we need to consider the part they play in the natural aquatic ecosystem. Macroinvertebrates are an integral part of the aquatic food web. They help to cycle energy though the system by breaking down organic material, harvesting algae, shredding course material, feeding on other macroinvertebrates or smaller micro-invertebrates and being eaten by larger vertebrates like platypus, fish and water rats. Without them, the system may start to fail, organic material is not broken down in the same way, fish and platypus have no food and twigs and leaves will start to pile up.

Not only do these little macroinvertebrates help keep aquatic ecosystems healthy; they can also let us know what condition the system is in!

Each different type of macroinvertebrate has a known tolerance to aquatic pollution. You can assess the health of the waterway by collecting a sample of macroinvertebrates from a stream and assessing what you find. If you find lots of pollution tolerant bugs, it's likely that your stream is in poor condition; however if you find many sensitive bugs the opposite may be true.
This is just one of the ways you can use macroinvertebrates to assess waterway health - it's the Waterwatch way, which is very similar to the method used by other environmental agencies in Victoria.

If you're interested in conducting a macroinvertebrate survey at your local waterway, please call one of our Waterwatch team on 03 5448 7124.

For more information on macroinvertebrates please read the following:

• Macroinvertebrates Fact Sheet
• Salinity Tolerances of Freshwater Macroinvertebrates Fact Sheet