A microalgae bloom is suspected to be behind a mass fish and octopus die-off along South Australia’s Fleurieu Peninsula, with dozens of dead marine animals washing ashore at Encounter Bay and Basham Beach. The Department of Primary Industries and Regions (PIRSA) and the Environment Protection Authority (EPA) are investigating the incident, which also caused health complaints—such as sore eyes, coughing, and blurred vision—from beachgoers at Waitpinga and Parsons beaches, prompting temporary closures.

EPA marine scientist Sam Gaylard said the bloom was likely driven by prolonged hot, calm weather, which created ideal conditions for phytoplankton growth. The bloom is producing discoloured foam and appears to be affecting primarily reef-attached species, potentially through irritation or oxygen depletion. While such blooms are not unusual for this time of year, the current scale is considered atypical. Scientists have collected water and fish samples to identify the microalgae species and determine whether it is acting as a toxin or physical irritant, with results expected within a week. Authorities advise the public to avoid affected areas and report any further incidents.

Read the full ABC article by Eva Blandis and Caroline Horn here: https://www.abc.net.au/news/2025-03-18/algae-bloom-likely-cause-fish-deaths-foam/105064874