Some of Australia’s best scientists gathered in late 2014 to discuss possible restoration and management options for the Noosa River.
It was the first time such a holistic approach had been applied to the Noosa River, in the quest to improve the diversity of aquatic species, such as prawns, bream, mullets and crabs.
The panel of 10 scientists agreed that one of the most effective way to improve biodiversity was to restore some of the oyster ecosystems that once dominated the Noosa River.
Check out the detailed report from the workshop.
These ecosystems are made up of oysters, mussels and a multitude of other creatures, offering a whole suite of ecosystem services, and work just like coral reefs as fish factories.
Oysters are incredible filter feeders. They eat by pumping large quantities of water through their body and remove algae and nutrients. This makes the water clearer and cleaner for seagrasses and other marine life. Half a hectare of oyster reefs can filter the equivalent of 36 Olympic swimming pools of water every day.
The Nature Conservancy conducted a preliminary scoping study in early 2015, to determine if there were still enough oyster larvae (known as spat) in the river to create new ecosystems.
The results showed good spat settlement within the estuary and the study recommended installing a number of pilot structures for further monitoring and assessment.
Noosa Council co-funded and provided in-kind support for a small scale oyster restoration unit trial.
A University of Sunshine Coast (USC) project team identified that 15 sites were needed for the oyster restoration units, which were placed in a range of locations in the Noosa River and lakes.
These trial units were not reefs, but experimental units specifically designed to help provide answers to some key questions associated with the project. They consisted of nine coir bags filled with cleaned oyster shells, at each of the 15 sites.
USC established a biannual monitoring program, with clear monitoring methods and performance targets.
In November 2018, the first year results indicated excellent recruitment of oysters in the trial units and no negative impacts on the adjacent environments.
The oysters hadn’t yet joined together but this wasn’t expected after just 12 months. There was some signs of propeller damage to a couple of the reefs, and these were repaired.
Two months later, in January 2019, a further inspection found much more widespread damage, thought to be from propellers and anchors over the busy Christmas period, and 10 of the 14 units were removed. The remaining units continued to be monitored with a second year and final report.
As well as this monitoring, USC also undertook various other studies, including the way the way fish used the new experimental units and provided a detailed report on the outcomes.
Once the Noosa River was full of oysters, the Kabi Kabi came from all over the region to eat here. Now they are gone. In areas of the world where oyster ecosystems still occur, they are areas of high biodiversity, much more so than muddy substrates.
Years of carefully-designed trials in Noosa River have indicated that a project can succeed. In recent years many countries, states and local areas have begun the process of trying to restore these habitats in recognition of this.
No organisation in the world has more expertise in this area than The Nature Conservancy. The Nature Conservancy is one of the world’s largest practical conservation organisations, working in over 70 countries, with over 400 scientists on staff and links to every major research institution in the world.
The Nature Conservancy approached Council in late 2018 to enter into a partnership, where both parties provided $1.2M each, to restore some of the lost oyster ecosystems of the Noosa River. A partnership agreement was endorsed by Council in 2019 and a TNC project team was on the ground in early 2020.
A project plan was endorsed by Council in July 2020, and the first oyster ecosystems planned to be in the river in 2021.