Oysters are back in Moreton Bay thanks to a successful oyster restoration project led by Griffith University marine scientists in partnership with fishing conservation charity OzFish. The project aimed to restore the dwindling oyster population in the area and improve the overall health of the ecosystem. The scientists and volunteers built oyster baskets or ROBs (robust oyster baskets) and deployed them at a 19-hectare site in the Port of Brisbane, where the oyster population had been severely depleted due to overharvesting and the destruction of reefs for lime-burning.
A team of Griffith University marine scientists recently analyzed the animal populations living on and around the oyster baskets and found that they now support over 3 million oysters and 4.5 million other animals, such as crabs. The study is the first comprehensive census of life on the oyster baskets and provides a solid basis for estimating the success of the restoration project. The researchers discovered that the ROBs were very stable, inexpensive, portable, and easy to deploy, and formed sturdy clumps of oysters in about 12 months.
Lead researcher Marina Richardson, an expert in shellfish biology and ecology in Griffith's Coastal and Marine Research Centre, explained that oyster reefs disappeared before living memory and were the kidneys of our waterways. She added that declining water quality and the removal of habitats prevented reefs from naturally recovering, and therefore required intervention.
"The benefits of restoring oyster populations in these shallow seas are enormous," Richardson said. "The primary cause of the decline in oyster populations was the destruction of reefs for lime-burning and unregulated and unsustainable harvesting following European arrival in the 1800s, so by the early 1900s, the oyster industry was in a state of collapse. Restoration is generally expensive, and it's why a lot of restoration is unable to be scaled up. But because ROBs don't rely on hatchery-produced spat, their use can be widespread."
The restoration project aligns with the Sustainable Development Goals (SDGs) set by the United Nations in 2015, which aim to end poverty, protect the planet, and ensure that all people enjoy peace and prosperity. Specifically, the project contributes to SDG 14, Life Below Water, which aims to conserve and sustainably use the oceans, seas, and marine resources. It also promotes sustainability by restoring the ecosystem's natural balance and improving water quality, which can have a positive impact on the global society's well-being.
Professor Rod Connolly, Director of Griffith's Coastal and Marine Research Centre, who helped calculate the project-wide benefits, said the census of life on the oyster baskets provides a solid basis for estimating current success and how future restoration efforts can help coastal waters recover and thrive again.
"This oyster reef restoration project will return vital ecosystem services such as water filtration and the establishment of habitats and foraging grounds for fish and invertebrates," Richardson said.
"With the initial results showing great success of the ROBs restoring oyster reefs, the team said the next stage of the project would be large-scale active restoration, which would require working further with Marine Park authorities and existing legislation to deploy to ROBs to other locations."
The restoration of oyster reefs through the use of novel and inexpensive ROBs holds significant potential to contribute towards the achievement of Sustainable Development Goals related to biodiversity conservation, marine ecosystem restoration, and sustainable production and consumption. By restoring oyster populations, this project can improve water quality and provide important ecosystem services, such as water filtration and the establishment of habitats and foraging grounds for fish and invertebrates. This project's success highlights the importance of sustainable and innovative approaches to environmental restoration and management, and their potential to contribute towards building a more sustainable, equitable, and resilient global society.
More information: https://phys.org/news/2023-04-oysters-brink.html