After Months Of Toxic Algae Bloom Off S. Australia's Coast, 200 Species Killed, Including Sharks, Rays, Octopus
More than 200 marine species, including deepwater sharks, leafy sea dragons and octopuses, have been killed by a toxic algal bloom that has been affecting South Australia’s coastline since March. Nearly half (47%) of the dead species were ray-finned fish and a quarter (26%) were sharks and rays, according to OzFish analysis of 1,400 citizen scientist reports.
Cephalopods – such as squid, cuttlefish and octopuses – accounted for 7%, while decapods – crabs, lobsters and prawns – made up 6% of species reported dead or washed up on beaches. The OzFish South Australian project manager, Brad Martin, said the harmful bloom – of Karenia mikimotoi algae – was like a toxic blanket that smothered marine life.
“It can suffocate fish from their gills, cause haemorrhaging by attacking their red blood cells, and act as a neurotoxin and attack the fish’s nervous system and brain, causing unusual behaviour,” he said. “This is why some fish and sharks are acting so strangely and why many of the dead have a red tinge – it is like a horror movie for fish.”
According to the state’s environment department, the algal bloom was being driven by an ongoing marine heatwave – with water temperatures 2.5C hotter than usual – as well as relatively calm marine conditions with little wind and small swells.
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https://www.theguardian.com/environment/2025/may/13/a-horror-movie-sharks-and-octopuses-among-200-species-killed-by-toxic-algae-off-south-australia