March 18, 2022

Constructed habitat bringing life back to channelised river

Further monitoring is planned to give a clearer picture of how restored sites are helping different aquatic species. Photo credit Jesse Collins
Further monitoring is planned to give a clearer picture of how restored sites are helping different aquatic species. Photo credit Jesse Collins.

Monitoring of aquatic life in the Harvey River has shown significant results less than a year after regional Western Australia’s first instream habitat drainage restoration project has been installed.

In a three-year trial, this channelised section of the Harvey River has had logs reintroduced to mimic fallen trees, and the banks planted with native species to combat weeds, prevent soil erosion and with time, grow to create shade that will cool water temperatures making them more suitable for aquatic life, such as the marron to live during the hot-dry summer months.

Members of the Harvey Aboriginal Corporation were invited to join the first monitoring survey following installation of the instream habitat, bringing their unique knowledge about the river and its importance to Bindjareb Noongar culture. They joined the excitement of some significant finds by the monitoring team from Harry Butler Institute - Murdoch University.

A major find at the restored sites were the Smooth Marron, a freshwater crayfish species endemic to south-west WA. They have not previously been detected in this part of the river in any of the previous surveys in 2009, 2018/19 and May 2021.

There was also a significant greater abundance of large Nightfish at the restored sites compared to the control sites, suggesting the species is favouring those new habitats.

These are really positive signs that the restoration is beginning to have an impact by providing more complex habitat and refuges for a more diverse range of aquatic species in the waterway.

Further aquatic monitoring, planned for Autumn of this year and also in 2023, will provide more data to determine the sustained effect of the restoration. It’s anticipated that, over time, the restored sites will support a greater diversity of species and species at different life stages.

It will be particularly interesting to explore whether the instream habitat project helps provide sanctuary for different species during the more extreme conditions that occur during the dry season.

The coming months will also see flora monitoring of the riverbank plantings, which inevitably will need longer to take shape.

"It’s so encouraging to see the results from installing logs for aquatic habitat in such a short space of time. It’s important to consider the long term as well, which is where revegetating the riverbanks comes in," said Ruth Cripps, a senior project officer with Greening Australia.

"As these trees and shrubs get established, they can also help shade the waterway, while preventing erosion and outcompeting weeds with their root systems. We can create a lovely habitat corridor where other biodiversity such as our cockatoos and other bird species can come and visit."

The overall results of the trial will be an important reference for future efforts to restore channelised river systems in Western Australia’s South West.

Helping the Harvey is part of Greening Australia’s Great Southern Landscapes program, an Alcoa Foundation funded project through the Three Rivers, One Estuary initiative, and forms part of the wider collaborative partnership between Harvey River Restoration Taskforce, Water Corporation, and Greening Australia under the ‘Marron More Than a Meal-Revive our Rivers Program’ funded by the Peel-Harvey Catchment Council, State Natural Resource Management Program, and Water Corporation.