A Harmful Algal Bloom Sweeps Along South Australia Coastline

02 May 2025

Algae Bloom Geographical Depiction - Harming marine life Kangaroo Island

Impact

Over the past few months, coastal South Australia, including waters around Kangaroo Island has been experiencing a significant environmental event that has left many residents and visitors concerned: a large-scale harmful algal bloom.

First detected in March 2025 near the Fleurieu Peninsula, the bloom has since spread across Gulf St Vincent, impacting marine life, water quality, and beach experiences across the region.

Here at Emu Ridge, we believe in keeping our visitors and community informed, especially when it comes to our natural environment and the island we all care so deeply about.

While smaller, localised algal blooms have occurred in South Australian waters before, we’ve never seen one on this scale. The South Australian Government has recognised this as a state-level environmental disaster, comparable to the floods and bushfires we’ve faced in recent years.

We feel deeply for the fishermen, seafood suppliers, and tourism operators who have been directly affected. The damage to marine ecosystems and industries has been heartbreaking.

For us at Emu Ridge, the impact is small in comparison, but still felt. The bloom has temporarily affected one of our popular group catering options: our delicious Kangaroo Island King George Whiting.

Latest update – 22/7/25 Algal Bloom Update – Government Announces $28m Support Package

The Premier has just announced a $28m harmful algal bloom support package which provides for industry support, science and research, communications, community support and clean up. This package includes yesterday’s announcement of Commonwealth funding ($14m).

Key elements of the package directly relevant to tourism businesses are:

$10,000 Small Business Support Grants for eligible small businesses.
$2m for public information campaigns focused on rebuilding confidence and driving visitation to our coastal regions and marine based tourism businesses and promoting the seafood industry and benefits of recreational fishing.
Financial counselling, mental health support and workforce advice to assist small businesses impacted by the harmful algal bloom to develop recovery and continuity plans, understand the short and long-term implications, and help manage financial and mental wellbeing.

(Harmful Algal Bloom Update 18/7/25) VERY SAD NEWS

As the Harmful Algal Bloom (HAB) continues to impact the community and business, Kangaroo Island Tourism Alliance will endeavour to keep us up to date and provide information. This is the most up to date information to date.
A State Government Taskforce has been assembled this week, in which SATC is represented by Chris Burford, Executive Director, Communications and Engagement, and chaired by the Chief Executives of DEW & PIRSA.

The bloom may linger well into winter and beyond, possibly a year or more pir.sa.gov.au+8Adelaide Now+8ABC+8.
Scientists are exploring natural suppressants like bioluminescent algae and other environmental factors that might help diminish Karenia levels Great Southern Reef.
Long-term ecological monitoring, habitat impact studies, and mental health support for fishing and coastal communities are being prioritized .

This is a major and ongoing environmental crisis with severe ecological, economic, and social consequences. Authorities are working together to monitor, support affected communities, and research longer-term solutions—but the bloom is far from over.

What Is an Algal Bloom?

Harmful algal blooms are rapid increases in algae, in this case, a species known as Karenia mikimotoi that can produce toxins or otherwise harm marine ecosystems. These blooms are often triggered by nutrient-rich waters, changing ocean temperatures, and weather patterns. In this case, several environmental factors seem to have played a role, including freshwater flows from the 2022–23 Murray River floods and unusually fluctuating sea temperatures.

What’s Happening Along the Coast?

This particular bloom has caused widespread marine animal deaths, with dead sharks, many fish, and shellfish reported from the Yorke Peninsula to metropolitan Adelaide beaches and Kangaroo Island. Locals have also seen discoloured water and brown foam washing up on shore.

According to South Australia’s Environment Minister, Dr Susan Close, “We are seeing the algae being very persistent” and it’s possible that it may not dissipate until next season! In fact, the bloom has been compared in size to Kangaroo Island itself and may last many months, even up to 18 months, all depending on future weather and ocean conditions. The algae can also settle on the seabed and lie dormant, potentially returning when conditions are right.

Is It Harmful to Humans?

Thankfully, this algal bloom is not considered toxic to humans, but it can cause skin, eye, and respiratory irritation, especially after contact with affected water. It’s best to avoid swimming in areas where water appears discoloured or has a strong odour or visible foam.

Why It Matters

Besides the clear environmental concerns, the bloom has already affected local seafood industries and tourism by creating uncertainty around water safety and marine health. It’s a reminder of how closely our livelihoods and well-being are tied to nature.

What Can We Do?

While there’s no quick fix for the bloom, scientists and government agencies are continuing to monitor its spread. The public can help by reporting sightings through the iNaturalist app, supporting citizen science efforts that track environmental change.

We encourage anyone visiting or living on Kangaroo Island to stay informed, support local businesses, and respect beach safety advice when exploring the coast.