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Murdoch University survey results in promising news for south-west marron
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Researchers from Murdoch University have uncovered important information that can help restore the health of fresh water ecosystems in the lower Harvey River.
Dr Stephen Beatty and Associate Professor David Morgan from Murdoch University’s Centre for Sustainable Aquatic Ecosystems, part of the Harry Butler Institute conducted the survey as part of the Marron, More than a Meal – revive our rivers’ project.
“The project has provided exciting new baseline data about the aquatic species in the lower Harvey River,” Dr Beatty said.
The project was an initiative of Greening Australia and the Harvey River Restoration Taskforce, funded by the Alcoa Foundation and the State Government’s Royalties for Regions program.
Local residents and students took part in citizen science days with the Murdoch University team to help gather data and reinforce the importance of careful management of local waterways and the marron population.
The iconic marron
The marron is the third largest freshwater crayfish in the world. It’s endemic to the global biodiversity hotspot of Southwest Western Australia. Major modifications to the local waterways along with the effects of climate change has seen wild populations of this native crustacean decline. With these changes to its environment, research is critical to establish data about the health of the ecosystem and marron population in this area.
The marron not only supports an important recreational fishery, it is also a great indicator of the health of the aquatic ecosystem. Considered a delicacy, the iconic species has been sustainably consumed by Aboriginal people for generations.
Given the popularity of marron among locals, engaging community has been a key part of the project, with residents and school students from the Peel-Harvey region taking part in citizen science days with the Murdoch University team.
The science
The Murdoch University team surveyed a series of highly modified drain sites in the Harvey River in spring 2018 and autumn 2019 to provide a pre-restoration assessment of ecosystem health.
Surprisingly in spring, the team found most sites housed high abundances of endemic native fishes and suggested they were good breeding habitats. However, in autumn the abundance of most native species crashed suggesting that the juveniles had not survived. They attributed this to the altered habitats lacking good refuge habitats for the fish.
Marron are more likely found in shaded parts of the waterway with a good variety of instream habitats, including deeper, cooler pools of water. The restored site was the only one to house the marron.
“The results were really promising as they suggest that if the sites are restored to a more natural state such as creating more diverse habitats, deeper pools and native vegetation, then they could have a high chance of supporting the fish that are already in the system, year-round,” Dr Beatty said.
“These little native fish are really important for ecosystem functioning as they are all carnivorous and do us humans a favour because their favourite foods include mozzie and midge larvae. They are also found nowhere else on the planet.”
The future for the marron
The data collected by Dr Beatty’s team is now being used to inform decision makers linked to the management of the Harvey River.
“Next steps are to develop a plan for another restoration demonstration site to prove that we can readily improve the condition of the lower Harvey River. The ultimate goal is to re-establish the mighty smooth marron to the lower Harvey River and in other degraded systems in the region.”
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Murdoch University survey results in promising news for south-west marron
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