For the past two years, Melbourne Water and MCMC's Waterwatch program have been training keen community members to collect and identify waterbugs in order to assess the health of Merri Creek. This citizen science project, which is open to anyone, helps provide a picture of the comparative health of Merri Creek and a basis for future actions to improve the condition of the waterway. In 2017 MCMC ran five waterbug sampling and identification sessions. The results showed that the lower, urbanised reaches of the Merri Creek only support waterbugs that are tolerant of pollution. Things are a little better in the upper reaches north of Epping where some of the sensitive waterbugs, less tolerant of pollution, are found (See table of waterbug pollution sensitivity in Read More section).
These results are consistent with surrounding land uses. Industrial and residential areas, and major roads, are a source of contaminated stormwater which affects waterbug survival. This is particularly the case in older urban areas where stormwater is untreated and flows directly through stormwater drains to Merri Creek. This in turn means that the Merri Creek is unable to support a healthy, diverse aquatic fauna.
How waterbugs help assess pollution
Waterbugs, or aquatic macroinvertebrates, are small animals without backbones that can be seen with the naked eye. A huge variety of macroinvertebrates live in our waterways, from dragonfly larvae (often called ‘mudeye’) to caddisfly larvae, diving beetles and waterboatman. These animals are crucial food sources to larger aquatic animals such as rakali (our native otter), frogs, platypus, fish and water birds. Different waterbugs withstand different levels of pollution, so they are useful biological indicators for understanding waterway health, as shown in the chart below.
|Pollution sensitivity||Macroinvertebrate examples||Waterway type and location examples|
|Very tolerant||Snails, flatworms, leeches, mosquito larvae||Highly disturbed streams, inner city, industrial areas|
|Tolerant||Freshwater shrimp, amphipod, dragonfly||Disturbed streams, suburban streams|
|Sensitive||Caddisfly, mayfly, diving beetle||Streams with little disturbance, well vegetated streams in farmland or low density housing|
|Very sensitive||Stonefly nymphs, dobsonfly larvae||Streams with good water quality and habitat|
Waterbug monitoring takes place in autumn and spring at specific sites across Melbourne. To take part in the 2018 Waterbug Census, you’ll first need to attend training to refine your identification skills — contact us to find a session in your area and get involved. Here’s further information on the next training.
Waterbug Census is proudly supported by Melbourne Water.