An underwater bloom of toxic algae has wreaked havoc off the coast of South Australia since mid-March 2025. After eight months, this harmful algal bloom is the longest and one of the most environmentally devastating events ever recorded in Australian waters.
The algal bloom is predominantly in Gulf St. Vincent and has affected 30% of South Australia’s coastline. The bloom has affected more than 390 species, with more than 87,000 dead animals reported to the iNaturalist database.
There is still no end in sight for this environmental disaster. It’s impossible to know exactly what might happen to this vast toxic bloom this summer, as the ocean heats up.
