The bloom's extent is unprecedented, affecting approximately 30% of the state's coastline, an area roughly equivalent to 20,000 square kilometers. Despite hopes that winter conditions would mitigate the bloom, it has persisted and spread, now impacting regions including Gulf St Vincent, Spencer Gulf, Investigator Strait, and Backstairs Passage.
Marine biologist Mike Steer from the South Australian Research and Development Institute (SARDI) highlighted the severity of the situation, noting that the bloom's size and duration are unparalleled in both South Australia and Australia. The densest occurrences have been observed along the coast from the top of Gulf St Vincent down to Brighton Beach.
The causes of the bloom are multifaceted. Factors such as floodwaters from the River Murray in 2022-23, a cold-water upwelling in summer 2023-24, and a marine heatwave since September 2024 have contributed to the proliferation of the algae. Climate change-induced ocean warming and nutrient pollution are also believed to play significant roles.
The impact on marine life has been devastating, with over 500 species of fish, penguins, and marine mammals affected. Human health concerns have also arisen, with reports of asthma, skin and eye irritation, and coughing among beachgoers. The aquaculture, fishing, and tourism industries have suffered substantial economic losses, and several First Nations communities have described the ongoing bloom as a "cultural emergency."
In response, the state government has established an information website and hotline dedicated to the event and is working with federal authorities on mitigation efforts. Temporary fishing restrictions on certain species have been imposed to allow for recovery. However, the situation underscores the need for proactive environmental management strategies to prevent similar crises in the future.
