Fisheries vessel inspects harmful algal bloom

The vision reveals the impact of the harmful algal bloom across several important marine sanctuaries with suspected visual signs of the algal bloom and rough seas reducing visibility to less than two metres in places.

The Southern Ranger visited the Zanoni shipwreck in the Upper Gulf St Vincent Marine Park. The footage shows many of the sponges, cold water corals and other filter-feeding organisms have been clearly impacted at the shipwreck site.

Around the Aldinga Reef and the Rapid Head sanctuary zones many invertebrates, such as sponges and ascidians, still appeared to be healthy with colour retained in their structures. However, some of these were starting to show signs of stress with white patches appearing in places.

State government agencies are also taking weekly water samples at 18 sites across West Lakes, the Port River, the Patawalonga River and the end of four jetties at Largs Bay, Grange, Glenelg and Port Noarlunga.

The state government has also established a reference group to help industries and stakeholders respond to and recover from the algal bloom affecting South Australia’s environment and coastline.

The group will comprise representatives from Seafood Industry South Australia, RecFish SA, Conservation Council, Tourism Industry Council and First Nations groups.

The Harmful Algal Bloom Reference Group will:

• Represent sectors to identify key issues for government to consider in managing and recovering from the algal bloom.

• Identify opportunities to further engage with and provide more information to industry sectors, stakeholders and the community.

• Provide ideas for government consideration to support an expanded scientific monitoring program.

The group will report to the Harmful Algal Bloom Taskforce which met in Adelaide on Tuesday to discuss the latest updates on the algal bloom.

Experts believe there are three potential plausible contributing factors causing the bloom, which started in March:

• A marine heatwave that started in September 2024 – with sea temperatures about 2.5°C warmer than usual – combined with calm conditions, light winds and small swells.

• The 2022-23 River Murray flood washing extra nutrients into the sea.

• An unprecedented cold-water upwelling in summer 2023-24 that has brought nutrient-rich water to the surface.

The algal bloom has caused discoloured water and foam along parts of the state’s coasts and has affected various marine wildlife, including fish, sharks, rays, and a wide range of invertebrates.

Karenia mikimotoi does not cause long-term harmful effects in humans but exposure to discoloured or foamy water can cause short-term skin or eye irritation and respiratory symptoms, including coughing or shortness of breath.

If you are outdoors and experience irritation, go indoors, close windows and rinse exposed skin. If symptoms are more severe or do not resolve, seek medical advice from a GP and call 000 if it is a medical emergency.

People and dogs should avoid swimming or surfing in discoloured water, foam or where marine life is dead or in poor health.

Do not eat dead fish and cockles because of decomposition and spoilage. Fish caught live are safe to eat. Report fish deaths to FISHWATCH on 1800 065 522.

Dog owners should keep their pets under effective control to prevent them eating dead or dying fish, which may cause similar symptoms to those in humans.

No reports of dogs becoming sick from the algal bloom have been received but owners concerned about their pet’s health should take them to a veterinary clinic.

For public health advice, visit: Water quality alerts | SA Health.

For regular algal bloom updates, visit Department for Environment and Water - SA harmful algal bloom update bloom update