South Australia is facing a catastrophic harmful algal bloom of Karenia mikimotoi, now stretching across nearly 30% of its coastline. The scale of the bloom is too vast for existing technologies, but smaller-scale solutions could help protect vulnerable habitats like giant cuttlefish breeding grounds.

Causes: A “triple threat” of marine heatwaves (climate change), nutrient-rich floodwaters and upwellings, and habitat loss has made coasts especially vulnerable. Prevention: tackling these root causes will be the key.

Potential short-term solutions:

• Chemical: Modified clays that strip nutrients from the water show promise but remain experimental.
• Physical: Techniques like bubble curtains can protect aquaculture pens but are ineffective at large scale.
• Biological: Natural predators, bacteria, and algicides may help; healthy seagrass meadows already provide natural resistance.

Nature-based solutions:

• Restoring shellfish reefs – once spanning 1,500km in SA – could play a major role. Oysters filter huge amounts of water, removing algae and excess nutrients. Early restoration efforts show strong promise, with oysters thriving even in current bloom conditions.
• Protecting and expanding seagrass meadows and oyster reefs could rebuild the ocean’s “kidneys and immune system.”

Looking forward: The bloom will eventually fade, but climate change and nutrient pollution mean more are likely. Building resilient ecosystems through large-scale restoration and conservation, coupled with long-term monitoring, is essential. Without proactive, integrated action, costly algal catastrophes will become more frequent.

Read the full The Conversation article by Dr Dominic McAfee and Professor Sean Connell here: https://theconversation.com/how-could-we-clean-up-the-algal-bloom-262749