Toxic algal bloom devastates marine life and disrupts South Australia's maritime economy

A massive bloom of toxic algae has been declared a natural disaster by South Australia's premier, Peter Malinauskas, after wiping out hundreds of marine species and heavily impacting aquaculture and tourism along the state’s coastline.

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06 august 2025   |   12:21   |   Source: Gazeta Morska / PAP   |   Prepared by: Kamil Kusier   |   Print

Zakwit toksycznych wodorostów Karenia mikimotoi który objął już ponad 4500 km wód przybrzeżnych uznany został za klęskę żywiołową

First detected in March, the bloom has now spread across an estimated 4,500 square kilometres of coastal waters. According to environmental scientists, the phenomenon has been intensified by a persistent marine heatwave, with sea surface temperatures 2.5°C above average since 2024.

– Over 400 marine species have been killed or decimated by this bloom – Peter Malinauskas told ABC News. – Let’s call it what it is: a natural disaster.

Economic fallout and emergency response

The bloom, caused by the explosive growth of Karenia mikimotoi, poses a severe threat to marine ecosystems. The decomposition of these algae reduces oxygen levels and damages the gills of fish, leading to mass die-offs. As a result, multiple oyster and shellfish farms have been forced to shut down temporarily, hitting the local seafood industry hard.

In response, both the South Australian government and the federal government have announced relief packages worth 9.11 million USD each, supporting water clean-up operations, environmental monitoring, and direct assistance to affected businesses.

Local residents have reported more than 13,850 instances of dead marine life – including sharks, rays, fish and invertebrates – via the iNaturalist platform, highlighting the scale of the ecological damage.

A global wake-up call

Marine biologists warn that this event is part of a broader trend: harmful algal blooms are becoming more frequent and more destructive, driven by rising sea temperatures and human-induced nutrient pollution in coastal waters.

– What’s happening off the coast of South Australia is not an isolated event – one marine ecologist noted. – It’s a warning sign for the global maritime sector, especially aquaculture, tourism and coastal economies.

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zakwit wodorostów Australia Południowa katastrofa ekologiczna Karenia mikimotoi rybołówstwo i klimat

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