A mysterious foam appearing on a beach in South Australia is believed to be responsible for making over 100 surfers sick and causing the death of several marine creatures, including sea horses, fish, and octopuses.
Health authorities have closed the Waitpinga and Parsons beaches, located about 80 km south of Adelaide, and stated that the foam could be caused by a microalgae bloom, triggered by high temperatures, calm waters, and an ongoing marine heatwave.
Surfers in the area have complained of blurry vision, irritated eyes, coughing, and breathing difficulties.
"The sea is covered with a yellow, dense, heavy foam with a lot of green, slimy, sticky matter on the beach, at the water's edge," said surfer Anthony Rowland, quoted by The Guardian.
Rowland posted online images of dead marine creatures found on the beach, including a species of sea horses. He said there are "visible signs that something strange is in the water."
The photos show the foam bubbling over rocks and forming colorful, serpentine lines in the sand.
"Some of the bubbles in the foam have a rainbow effect," Rowland added.
After entering the water over the weekend, he experienced respiratory issues. "I felt very hoarse. It was like inhaling a strong cleaning product, when you clean the kitchen sink or something like that. It hit me right in the throat," he explained.
The response to his post was "absolutely overwhelming," Rowland said, adding that he and other surfers concluded that over 100 people have been affected. He is also concerned that the phenomenon is spreading to other beaches on the Fleurieu Peninsula.
"In the last 24 hours, dead fish have been found along the coasts of Victor Harbor, Middleton, Encounter Bay. The phenomenon has clearly reached the Victor coast, and at Middleton, there are dead octopuses," he stated.
Beaches Closed Preventively
A spokesperson for the state's environment department stated in a release that the beaches were closed "for safety," and authorities are investigating the situation.
"Waitpinga and Parsons beaches, located in the Newland Head Conservation Park, will be temporarily closed to the public in response to a fish mortality event in the area," the official said.
"The beaches will be reopened as soon as possible."
Possible Explanations
The phenomenon is believed to be caused by a microalgae bloom generated by high temperatures and calm waters, amidst an ongoing marine heatwave. The water temperatures are currently 2.5°C higher than normal, and the lack of wind and small waves contribute to maintaining these conditions.
South Australia is facing drought and has recently experienced periods of extreme heat.