An innovative study will have significant benefits for native mussel populations and inform environmental water deliveries. The study is funded by the Commonwealth Environmental Water Holder (CEWH).
Mussels in the Murray-Darling Basin play an important role in rivers and billabongs. They:
- filter water
- recycle nutrients
- shape riverbeds
- provide food and shelter for other animal
- indicate water quality.
For First Nations communities, mussels have deep cultural importance with evidence of use going back thousands of years.
These species face several threats that have reduced their habitat and disrupt water flows. These include:
- droughts
- river regulation
- salinity
- pollution
- climate change.
During the 2017-2020 drought, millions of mussels died due to dried rivers. With climate models predicting more frequent and intense droughts, it is important to know where mussels survive and what they need.
A project led by the Gulbali Institute at Charles Sturt University has developed an environmental DNA (eDNA) tool to detect river and billabong mussels. Mussels naturally shed tiny fragments of DNA into the water through skin, waste or mucus. Scientists collect water samples and analyse them in the lab to check for mussel DNA. This method is faster, safer and often more accurate than traditional surveys, which require digging by hand in cold murky water.
Tests show eDNA is very accurate even at low DNA levels. Field surveys on the Ovens and King rivers found river mussels at 15 of 23 sites using eDNA but only eight using traditional methods. In six places, river mussels went undetected by physical searches.
This shows eDNA can be a very effective tool for monitoring.
"eDNA based monitoring is becoming increasingly popular for biodiversity surveys across the Murray-Darling Basin," said Elka Blackman, PhD Candidate at Charles Sturt University.
"A major advantage of this approach is that a single eDNA sample can be used multiple times, reducing field effort. Further validation may be used to infer species biomass and identify reproductive events."
For the CEWH, these advances are significant. Reliable detection helps track mussel distribution, understand their habitats and guide water flows to protect them. In a changing climate, eDNA gives freshwater mussels a better chance to survive and thrive.
