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South Australian toxic algal bloom killed more than 8,000 sharks and rays, including endangered species

Ecologists and experts fear mass mortality event that began in March 2025 may have led to the collapse of some local populations

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Toxic Algal Bloom Devastates Shark and Ray Populations in South Australia

In a shocking environmental disaster, over 8,000 sharks and rays have perished in South Australia due to a toxic algal bloom, marking one of the largest mass mortality events recorded globally. This incident not only raises alarms about the health of marine ecosystems but also invites scrutiny into the potential corporate negligence and environmental policies that may have contributed to this crisis. Investigators and environmentalists are now questioning the long-term implications for biodiversity and the integrity of marine habitats.

The Scale of the Tragedy

The algal bloom, caused by the rare and toxic species Karenia cristata, has led to the deaths of numerous marine species, including endangered ones. According to marine ecologist Janine Baker, the analysis of citizen science and government records revealed that the fatalities included approximately:

  • 4,460 southern fiddler rays
  • 850 Port Jackson sharks
  • 670 cobbler wobbegongs
  • 650 western shovelnose rays

Prof. Charlie Huveneers from Flinders University emphasized that the scale of this event is unprecedented. The diversity of species affected—31 in total—highlights the vulnerability of marine life to such blooms, particularly those endemic to South Australian waters.

![Image of sharks and rays affected by algal bloom](search_query:

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South Australian toxic algal bloom killed more than 8,000 sh | The Theorist