The recent widespread algal bloom in South Australia’s coastal waters has sparked a heated discussion. Scientists and environmentalists are in the thick of the debate about just what’s causing it. Following the floods of 2022-23, millions of dead fish littered beaches from Newcastle to Wollongong on the south coast. Among them were thousands of carp. According to the South Australian government, this bloom has been related to recent floods, a marine heatwave, and cold-water upwelling. Experts like Dr Luke Mosley are disputing this perspective, offering new explanations as to where the bloom actually originates.
Mosley has spent the last 20 years conducting research in and around the often-overlooked Murray River. The real crux of his paper comes when he argues that the link between the floods and the algal bloom is weak at best. He proposes that a massive upwelling event could have triggered the bloom on its own. He thinks a marine heatwave could have contributed, all independent of the river’s floodwaters’ effects. On 1 January 2023, satellites recorded a major brown plume extending from the mouth of the Murray River. Not surprisingly, this breakthrough raises new questions about nutrient availability and timing.
Diverging Perspectives on Environmental Events
The South Australian government has declared the flood to be one of three “extraordinary” environmental circumstances. It’s the single, most important factor driving the growth of the harmful algal bloom. Officials have cited a number of reasons for the flooding. They cite an unprecedented marine heatwave and a cold-water upwelling event that developed in the summer of 2023-24. Dr. Mosley stresses that there isn’t enough evidence connecting the floods to the bloom’s development.
“Because there was a big time lag between the flood and the onset of the River Murray bloom … that time lag and the high energy mixing out in this coastal ocean here meant it was unlikely that the nutrients were available at the time, certainly in relation to the River Murray flood,” – Alec Rolston.
Dr Alec Rolston, director of the Coorong, Lower Lakes and Murray Mouth Research Centre, shares Dr Mosley’s scepticism. He ardently advocates the need for more investment at the state and federal level. This funding will enhance our scientific understanding of algal blooms and their root causes. If we don’t invest in robust, long-term funding for our marine observation programs, scientists will continue to be on the back-foot when it comes to these ecological obstacles.
“The lack of a long-term, marine observation-type program means that you’re always reactive,” – Luke Mosley.
Ongoing Inquiry into Environmental Impacts
The investigation in to South Australia’s algal bloom has aroused considerable public interest and media pressure. With hearings held in various locations including Adelaide and Port Lincoln, stakeholders are eager for clarity regarding the contributing factors. The last day of hearings is scheduled for Parliament House in Canberra on Wednesday. We should see a draft report by no later than October 28.
As these conversations continue, we must heed the reminder from Dr. Rolston about the urgency of not just recognizing, but collectively addressing climate change. He claims that urgent action is needed to address climate change and alleviate its impact on our oceans.
“Climate change is real. It’s happening. It’s happening now, and we’re seeing the impacts of that,” – Alec Rolston.
To address these challenges effectively, experts advocate for a paradigm shift in how governments approach scientific funding and environmental management.
“We need to invest in the science to make sure that we can undertake that planning to reduce and mitigate the impacts as best we can,” – Alec Rolston.
