Oyster Reefs Could Help Heal South Australia’s Algal-Bloom Crisis

The bloom that won’t go away

South Australia’s coastline is still choking under one of the worst algal blooms in its history. What began as an environmental concern has become a full-scale ecological and economic emergency, suffocating marine life, destroying habitats and negatively impacting some products within the seafood industry (BBC, 2025).

Communities along the Spencer Gulf and Eyre Peninsula are now facing ongoing beach closures, biodiversity loss and a reduction in local tourism. Quick fixes, like chemical treatments or containment barriers, can only go so far. What’s needed are long-term, regenerative solutions that address the cause, not just the symptom. And conservation scientists believe one of those solutions might be sitting quietly on the seabed. Or at least, it used to.

How oysters can help

Before dredging, pollution, and over-harvesting wiped out 99% of Australia’s shellfish reefs, native oysters and mussels played a crucial role in keeping coastal waters healthy (The Nature Conservancy Australia, 2025). These reefs acted like natural filtration systems by cycling nutrients, reducing sediment and creating habitat for hundreds of marine species. To put it into perspective, each oyster can filter a bathtub of water (200 litres) every two days. So oysters can play a powerful role in removing excess nutrients and algae from water before they spiral into harmful blooms (University of Adelaide, 2025). Restoring these reefs could therefore be one of South Australia’s most powerful tools for clearing coastal waters and rebuilding ecological balance.

Research from The Nature Conservancy (TNC) shows that restored reefs also do far more than filter algae. They stabilise ecosystems, boost biodiversity, and protect coastal economies that rely on healthy oceans. Pilot sites such as Windara Reef near Ardrossan and Glenelg Reef off Adelaide are already showing promising results as oysters there are filtering bloom-affected waters and helping fish and other species return to previously degraded areas (The Nature Conservancy Australia, 2025).

What else is being done to tackle the algal bloom

While oysters are part of the solution, the South Australian and Federal Governments are also funding a wider strategy to understand, mitigate and prevent future blooms. Through the $102.5 million Algal Bloom Summer Plan, more than $37 million has been dedicated to long-term environmental protection and marine research (Department for Environment and Water, 2025).

This includes $20.6 million invested directly in nature-based restoration projects:

• Large-scale native oyster reef restoration, as mentioned, led by The Nature Conservancy Australia.

• Community shellfish reef restoration involving local volunteers and Traditional Custodians.

• Seagrass and blue carbon restoration, to store carbon and absorb excess nutrients.

• Breeding programs for threatened and vulnerable marine species.

• Advanced water monitoring and offshore analysis to track nutrient loads.

• AI “Cytobots” deployed for real-time detection and mapping of harmful algal species.

• Establishment of an Office for Algal Bloom Research, coordinating scientific and policy efforts.

• Algal bloom mitigation research, trialling new prevention and containment methods.

These efforts complement broader community support measures such as increased Surf Life Saving patrols, daily beach clean-ups, and economic grants for fisheries and coastal businesses, helping affected communities stay afloat while long-term restoration takes hold. Together, these initiatives reflect a shift toward nature-positive infrastructure. Oyster by oyster, reef by reef, we’re big believers that economic and ecological recovery can grow side by side.

References

BBC News (2025) South Australia’s “red tide” threatens marine life and tourism. https://www.bbc.com/news/articles/cqxewn0z2v8o

Department for Environment and Water, Government of South Australia (2025) South Australia’s algal bloom – all your questions answered. https://www.environment.sa.gov.au/goodliving/posts/2025/07/sa-algal-bloom-faqs

The Nature Conservancy (TNC) Australia (2025) Science has the solution to end algal blooms. https://www.natureaustralia.org.au/what-we-do/our-priorities/oceans/ocean-stories/beating-the-bloom/

University of Adelaide (2025) Steps to clean up the algal bloom – key potential control mechanisms. https://www.adelaide.edu.au/environment/news/list/2025/08/19/steps-to-clean-up-the-algal-bloom-1?utm_

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