Algal bloom situation update
Overview
Parts of South Australia continue to be affected by the ongoing microalgae bloom, Karenia species.
A marine heatwave (MHW) has been affecting southern Australia since September 2024. Like heatwaves on land, MHWs are periods of exceptionally warm ocean temperatures. These elevated temperatures are considered to be a contributing factor to the algal bloom.
This is a dynamic situation as the bloom travels depending on weather and water conditions and the impact on people in these areas can therefore be unpredictable.
The last time a large event of this type of Karenia species was recorded in SA was in 2014 in Coffin Bay.
Nothing can be done to dilute or dissipate the bloom.
Government agencies are working together to monitor the situation, conduct sample tests at various locations, and to ensure the community has access to the environmental, primary production and health information they need to safely enjoy the coast.
Similar outbreaks around the world have generally lasted between a week to several months depending on wind, rain and ocean temperature fluctuations.
All beaches in National Parks are open and accessible to the community. Visitors should follow health advice, provided via signs that have been installed at public entry points to the beaches, and avoid contact with discoloured or foamy water.
Latest update
Since the last update on 27 May 2026, seasonal cooling of South Australian coastal waters has continued.
Sea surface water temperatures show most of the state’s waters are within ±1ºC of the long-term average conditions expected for this time of the year.
Warmer sea surface temperatures anomalies are observed in patches across the upper gulf regions and off the southern continental shelf.
Moderate marine heatwave conditions are present in upper Spencer Gulf and Gulf Saint Vincent.
The availability of satellite-derived measures of chla concentrations has been constrained by cloud cover since the last update. However, the latest images on 1 June and 2 June 2026 show current chla levels across much of Gulf Saint Vincent and Spencer Gulf remain near or below the long-term average concentrations expected for this time of year.
Localised regions currently experiencing elevated chla concentrations include near Hardwicke Bay on the Yorke Peninsula and from Port Lincoln to Tumby Bay in Spencer Gulf.
Comparison of the daily changes in chla concentrations on 1 June and 2 June 2026 shows increases in chla concentration in the lower southwest region of Spencer Gulf near Port Lincoln have extended to just north of Tumby Bay with the largest increases observed near the coast extending from Louth Bay to Tumby Bay.
Smaller patches of increasing chla are observed near Hardwicke Bay and Edithburgh, upper Gulf Saint Vincent, and Victor Harbor.
Oceanographic forecast modelling of particles released from multiple source regions was used to predict water mass movement over a 5-day period commencing 4 June 2026.
Download the full SA algal bloom situation update ( ).
Modelling
Latest oceanographic forecast modelling of particle trajectories representing microalgae for different source locations using the PIRSA eSA-Marine system. Blue arrows indicate the model wind speed and direction. Red lines highlight the convex envelope, or polygon, with the shortest perimeter that encloses the particles tracked from each source location across the simulation period.
Impacted wildlife
Karenia species can cause marine species mortalities at varying concentrations and is known to impact the gills of fish.
Report any marine mortalities to Fishwatch on 1800 065 522 so they can be added to the testing regime being carried out by PIRSA.
We encourage anyone who discovers dead or sick marine wildlife to contact their local National Parks and Wildlife Service office.
Health advice
South Australian beaches can still be enjoyed but it’s best to stay away from abnormally foamy or discoloured water, which may cause irritation.
If you do enter this water, or experience any irritation, rinse off with clean water afterwards.
Contact with water can cause:
- eye irritation
- skin irritation (uncommon).
Contact with aerosols can cause:
- eye irritation
- cough and shortness of breath.
If you notice symptoms, move away from the beach or water. Most symptoms will resolve within hours of leaving the area.
From time to time, depending on weather conditions, strong winds and wave action may cause people living near affected beaches to experience eye, skin or respiratory symptoms while at home. If this happens, stay indoors with windows closed until conditions change or symptoms resolve. Some people may find using an air purifier helpful.
Some algal species, including Karenia cristata, can release biotoxins (specifically brevetoxins) into the air through wave action. Exposure to aerosols containing algal particles or brevetoxin may trigger symptoms in people with asthma.
People with asthma are advised to:
- carry their reliever medication with them while on beaches, especially when there is abnormally thick foam or discoloured water
- take their preventive medication as prescribed
- check their asthma management plan is up-to-date.
See water quality alerts on the SA Health website for further health advice.
Food safety
PIRSA conducts regular ongoing monitoring of shellfish harvesting areas by the South Australian Quality Assurance Program (SASQAP), which conducts a rigorous ongoing testing regime aimed at assuring consumers of commercially harvested oysters, mussels, cockles and scallops that they are safe to eat. As part of this program, harvesting areas are often temporarily closed as a precaution to ensure food safety standards are upheld.
Currently this testing regime has led to closures of some oyster growing and harvesting areas and the commercial harvesting of pipis.
The majority of oyster harvesting areas remain open with produce from those areas safe to eat. Regular ongoing testing in these open harvest areas continues to ensure the harvested produce food safety standards are upheld. This means there is no public health concern.
If you catch fish, crabs, prawns, lobsters or squid yourself, they are safe to eat if cleaned thoroughly and gutted before cooking.
Do not eat bivalve molluscs (like oysters, cockles, mussels, pipis and scallops) or abalone that you catch or collect yourself, as they have not been tested for brevetoxin.
Science forum
A forum was held on 3 June 2025 that was open to the scientific community and brought together leading scientists from State and Federal government agencies, national research institutes and universities, and the private sector. Experts from New Zealand on algal blooms also provided valuable insight.