South Australia: Escalating Harmful Algal Bloom Sweeps Through Iconic Coastal Regions, Prompting Urgent Marine Warnings and Coordinated Environmental Measures Here’s Everything Travelers Need to Know – Travel And Tour World

A naturally occurring algal bloom that first appeared in March along the Fleurieu Peninsula has now reached the Port River, prompting a major response from environmental authorities across South Australia. The bloom, caused by the Karenia species of algae, has been found in notably high concentrations near Garden Island and the Outer Harbor boat ramps, raising serious concerns for marine life, public health, and the local tourism economy.

Intensified Monitoring Efforts Across the Coast

To track the progression and intensity of the bloom, weekly water sampling is underway at 17 coastal sites, including West Lakes, the Port River, Patawalonga River, and jetties at Largs Bay, Grange, Glenelg, and Port Noarlunga. These checks are part of a broader environmental surveillance program to detect harmful algae and protect coastal ecosystems.

In the Adelaide Dolphin Sanctuary, located in the Port River, specialists are closely monitoring both water quality and the well-being of the local dolphin population. While there is currently no confirmed danger to these marine mammals, scientists and conservation teams remain vigilant.

Ocean Temperatures and Algal Growth

Recent data indicates that surface sea temperatures have dropped in shallow waters, yet deeper ocean areas—particularly around Kangaroo Island and the southern Yorke Peninsula—are experiencing ongoing marine heatwave conditions, with temperatures ranging from 1 to 2°C above normal.

Satellite imagery shows a significant rise in chlorophyll-a levels—an indicator of algal presence—throughout Gulf St Vincent. Elevated readings have been documented from Troubridge Point to West Lakes, as well as in waters between Coobowie and Port Wakefield, Port Lincoln to Arno Bay, Hardwicke Bay to Wallaroo, and across the Limestone Coast from Meningie to Robe.

Effect on Marine Wildlife

The situation worsened following a major storm on June 6, which coincided with several fish kill events along beaches at:

• North Haven (between the river mouth and the marina)
• Tennyson Beach
• North of Grange Jetty
• South of Christies Beach Surf Life Saving Club
• Port Broughton

Subsequent testing revealed the presence of Karenia algae in the Coorong North Lagoon, especially from Seven Mile Basin to Long Point. Experts believe the bloom reached this area following a cold front on May 26, coupled with high tides the next day. Although the Coorong remains open to visitors, they are urged to stay away from discoloured or foamy water, and from areas where marine animals appear dead or in distress.

Health Guidance for the Public and Pets

While Karenia mikimotoi poses no long-term health risks to people, exposure to affected waters can lead to temporary irritation—including itchy skin, sore eyes, and mild respiratory symptoms. Health authorities recommend:

• Avoiding contact with discoloured or foamy water
• Rinsing off immediately after exposure
• Seeking medical attention if symptoms persist
• Calling emergency services for severe reactions

Pet owners should also exercise caution, ensuring dogs are kept away from contaminated water and do not consume dead fish or other marine life.

Seafood Consumption and Safety Measures

Authorities stress that dead or dying fish and shellfish found on beaches should not be consumed. However, seafood caught alive from approved areas remains safe for consumption. Residents and visitors are encouraged to report marine life deaths via the FISHWATCH hotline.

As a safety precaution, commercial pipi harvesting was halted on April 16 near the Murray Mouth, and on May 19, restrictions expanded to include American River, Port Vincent, and Stansbury. Ongoing testing is being carried out to ensure product safety in permitted areas.

Root Causes Behind the Bloom

Scientists point to three interconnected environmental events contributing to this unusual bloom:

1. A marine heatwave beginning in September 2024, marked by water temperatures up to 2.5°C above normal, along with calm seas and light winds
2. A nutrient overload from the 2022–23 River Murray floods, which washed additional material into coastal waters
3. A rare cold-water upwelling during summer 2023–24, bringing nutrient-rich water to the surface

Events of this magnitude are uncommon in South Australia. The last significant bloom of this type was recorded in Coffin Bay back in 2014.

No Quick Fix, Just Careful Management

Experts explain that algal blooms can persist from just a few days to several months, depending on factors like wind, rainfall, and water temperature. Currently, there are no direct interventions available to remove or neutralize the bloom. The only reliable method is natural dispersal over time. Despite the ongoing bloom, coastal parks and beaches remain open, with informational signs in place to advise the public.

Clearing Up the Misconceptions

Authorities have clarified that the quarry sand used at West Beach and Henley Beach complies with strict environmental standards and is not linked to the algal bloom. Similarly, desalination plants, which discharge brine into the ocean, have not been found to contribute to algae growth. These systems are closely regulated and continuously monitored.

Potential Impacts on Tourism and Travel

The unfolding algae event has several key implications for South Australia’s coastal tourism sector:

• Health advisories and clear signage help maintain public trust
• Activities like surfing, beach rentals, and swimming may experience short-term declines
• Sites such as the Adelaide Dolphin Sanctuary could see reduced visitor numbers if wildlife health concerns rise
• Restaurants and seafood-related tours may be affected by harvesting bans, requiring greater transparency in sourcing
• Frequent updates through local channels are crucial to keep travelers and businesses informed

Wider Lessons for Global Coastal Destinations

This event is a timely reminder for coastal regions worldwide. Climate-related environmental shifts, such as marine heatwaves and algal blooms, are becoming more frequent. As a result, tourism boards and local governments may need to:

• Improve coastal monitoring systems
• Adjust management strategies to include environmental risks
• Educate visitors on how to enjoy coastal areas safely during such events

South Australia’s experience could serve as a valuable case study for similar regions facing the challenges of climate change and environmental unpredictability.

A Broader Wake-Up Call

The expansion of Karenia algae from Fleurieu Peninsula to the Port River underscores the delicate balance between natural marine dynamics and human activity. As tourism, wildlife, and public health intersect, this situation highlights the importance of sustainable coastal management, informed public communication, and continued scientific research to navigate future environmental challenges.