Ecologist Calls South Australia’s Coorong Algal Bloom a Wake-Up Call for Environmental Awareness

When South Australia’s algal bloom hit the Coorong, it turned the water a dark, tea-like color and left behind a grim scene of dead marine life. The bloom, caused by Karenia mikimotoi algae, has wiped out over 200 marine species. Contrary to hopes for relief from a storm in May, high tides spread the algae into the Coorong, an important wetland at the mouth of the Murray River.

Faith Coleman, an estuarine ecologist, noted that the algae has been multiplying rapidly due to the nutrient-rich waters. Among the casualties were benthic species like snails, shore crabs, and baby flounders—vital food for shorebirds and fish.

While some signs of improved conditions appeared, the stench of rotting fish lingered, suggesting that the algae could return. Coleman warned that with warming temperatures, the bloom might resurface. Recent reports indicated increased chlorophyll levels off the South Australian coast, a clear signal of rising algae concentrations.

Local fishermen like Gary Hera-Singh can attest to the devastating impact. He observed a dramatic shift as seawater brought the bloom into the lagoon. He described vast areas still affected, stating that in his 41 years of fishing, this was the worst ecological disaster he’s witnessed.

The Coorong—a 120 km stretch of water separated from the Southern Ocean by sand dunes—plays a crucial role in supporting fish, waterbirds, and other species. However, its health has been declining over decades, worsened by barriers built in the 1950s that altered water flow and increased nutrient levels.

Professor Peter Gell, a wetlands expert, highlighted that algal blooms reflect broader environmental shifts. Both the Coorong and the surrounding waters exhibit significant changes to their food web. As a Ramsar-listed wetland, the Australian government must report on changes, usually prompting restoration efforts.

Officials are currently assessing the situation. The Coorong faces stress from climate change, including rising sea levels and reduced river flows. Dr. Nick Whiterod, an ecologist at the Coorong Lower Lakes Murray Mouth Research Centre, noted that unusual algal blooms are alarming signals of environmental strain. The recent appearance of a tropical blue-green algae in Lake Alexandrina is a worrying sign for the years to come.

Overall, the Coorong is at a tipping point—driven by climate change and human impact. Experts warn that if conditions persist, the ecosystem might struggle to bounce back.

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