Craig Bohm of TNC with the latest recycled oyster shells.
Craig Bohm of TNC with the latest recycled oyster shells.

Recycling key to oyster-led river recovery

It doesn’t look like much now, but the oyster shells piling up on council land are actually the building blocks of a $2.4 million biodiversity comeback for the Noosa River estuary.

After these tasty treats are shucked for sale to Sunshine Coast eateries, instead of being chucked in the waste bin they are being recycled for a key environmental restoration project.

Reefs split council ranks

Oyster reef restoration ‘the real deal’

Acting Noosa Mayor Frank Wilkie said oyster reef restoration council partner The Nature Conservancy had been busy collecting used shells from local seafood distributors.

Cr Wilkie said they would be dried for about four to six months, recycled and mixed with rocks to create a foundation for new oyster reefs at various sites in the Noosa River.

“Adding hatchery grown oysters at these location will also help kickstart the process. Oysters and the reefs they form were once widespread in the estuary system,” Cr Wilkie said.

TNC project co-ordinator Craig Bohm said oysters took a lot of the nutrients out of the water and put it back into the sediment where it belongs, which helps fight algal blooms and stabilise the aquatic ecosystem.

The Nature Conservancy project officer for Noosa River oyster reef restorations Craig Bohm.
The Nature Conservancy project officer for Noosa River oyster reef restorations Craig Bohm.

“The oyster beds provide a diversity of places for animals to aggregate, grow and live, which adds to the complexity of life in the river,” Mr Bohm said.

“That complexity adds to the resilience of the river and helps restore important habitats.

“Oysters growing on rock walls, pylons and piers do not provide this diversity of ecosystem services.”

Mr Bohm said the project was trying to create a diversity of places where animals and plants can live.

“The sharpness and the different shapes that the shell and the rock provide in the substrate add to the variety of different animals that can be attracted to the place.

“Noosa is a special and we want to do the best we can in Noosa,” he said.

“We’ll certainly in this project will go steady and carefully and make sure people understand what we’re doing and support what we’re doing.

Building up a stockpile of recycled oyster shells for future reef building.
Building up a stockpile of recycled oyster shells for future reef building.

Cr Wilkie said TNC was also providing research and advice to the Noosa community on how seagrass beds may be restored and used to manage sediment in the Noosa River ecosystem.

Meanwhile, the Noosa Biosphere Reserve Foundation, which kicked off the initial oyster restoration trial, is supporting Griffith University research to help identify which oysters will do best in the Noosa River system.

A NBRF information update said researchers will use CSI-like environmental DNA technology to test the diversity of species present, building on the existing knowledge base developed through NBRF and its research partners.

“We hope that the new methods used will help us to detect oyster species that are rare or that live in areas that are difficult to access … perhaps it will even be able to tell us whether the elusive Noosa mud oyster still occurs,” the update said.

“This project also evaluates which surfaces are best for a range of oyster species to settle on. “To do this, a few different types of settlement plates and dead oyster shell were deployed over the 2019 Summer to catch baby oysters.

“Despite the dry conditions quite a few oysters were caught around the estuary and genetic analyses are underway to determine their identity.”

This project is due for completion by the end of 2020.