Toxic algae are turning South Australia’s coral reefs into underwater graveyards – and there’s no end in sight codigo promocional betboom

What struck Scott Bennett most were the razor clams.

The long saltwater clams, resembling old-fashioned razors, normally burrow into sand to avoid predators. But when Bennett, an ecologist, visited South Australia’s Great Southern Reef last month, he saw thousands of them rotting on the sea floor.

“100% of them were dead and wasting away on the bottom,” Bennett told CNN.

Since March, a harmful algal bloom, fueled by a marine heat wave, has been choking South Australia’s coastline, turning once-colorful ecosystems filled with thriving marine life into underwater graveyards.

The bloom has killed about 15,000 animals from over 450 species, according to observations on the citizen science site iNaturalist. They include longfinned worm eels, surf crabs, warty prowfish, leafy seadragons, hairy mussels and common bottlenose dolphins.

A sea creature washed onto the beach by a toxic algal bloom. A sea creature washed onto the beach by a toxic algal bloom. Stefan Andrews/Great Southern Reef Foundation A starfish is seen as toxic algal bloom washes dead and dying sea creatures between O'Sullivan Beach and Hallett Cove in Adelaide, Australia, on July 12, 2025. A starfish is seen as toxic algal bloom washes dead and dying sea creatures between O'Sullivan Beach and Hallett Cove in Adelaide, Australia, on July 12, 2025. Tracey Nearmy/Getty Images The algae have poisoned more than 4,500 square kilometers (1,737 square miles) of the state’s waters – an area larger than Rhode Island – littering beaches with carcasses and ravaging an area known for its diversity.

It’s “one of the worst marine disasters in living memory,” according to a report by the Biodiversity Council, an independent expert group founded by 11 Australian universities.

The toxic algal bloom has devastated South Australia’s fishing industry and repelled beachgoers, serving as a stark warning of what happens when climate change goes unchecked.

Once a bloom begins, there is no way of stopping it.

“This shouldn’t be treated as an isolated event,” Bennett said. “This is symptomatic of climate driven impacts that we’re seeing across Australia due to climate change.”

A toxic algal bloom washes dead and dying sea creatures onto Tennyson Beach in Adelaide, Australia, on July 11, 2025. A toxic algal bloom washes dead and dying sea creatures onto Tennyson Beach in Adelaide, Australia, on July 11, 2025. Tracey Nearmy/Getty Images A mysterious yellow foam It all started back in March, when dozens of surfers at beaches outside Gulf St Vincent, about an hour south of state capital Adelaide, reported experiencing a sore throat, dry cough and blurred vision after emerging from the sea.

Shortly after, a mysterious yellow foam appeared in the surf. Then, dead marine animals started washing up.

Scientists at the University of Technology Sydney soon confirmed the culprit: a buildup of a tiny planktonic algae called Karenia mikimotoi. And it was spreading.

In early May, the government of Kangaroo Island, a popular eco-tourism destination, said the algal bloom had reached its coastline. A storm at the end of May pushed the algae down the coast into the Coorong lagoon. By July, it had reached the beaches of Adelaide.