A little-known type of algae dominated a deadly algal bloom that caused significant harm to marine life in South Australia. The bloom, which covered approximately 20,000 square kilometers, resulted in the death of around one million animals [1]. This event occurred in 2025 and was among the worst environmental disasters affecting coastal waters.
The microalgae species responsible for this harmful algal bloom has been identified as being among the most toxic ever tested. Over the past year, a severe marine environmental disaster unfolded across many of South Australia’s coastal areas [2]. The bloom expanded in these regions, leading to thousands of fish deaths and other significant impacts on marine life.
Scientists have now confirmed that this microalgae species is one of the most toxic harmful microalgae ever studied. This finding underscores the severity of the environmental impact caused by the algal bloom [3].