South Australians living with asthma or other types of respiratory illness have been warned of a “potential risk” posed by a toxic algal bloom dominating the state’s coastline at a Senate committee inquiry into the natural disaster.
The Senate committee had its first public hearing on Tuesday, and heard there were now toxins in the bloom that could exacerbate asthma; that very little was known about the species in the bloom, and that even its cause was not fully understood.
It also heard locals and experts – particularly marine scientists – were very worried about the bloom that had killed more than 42,000 fish and marine animals from 500 different species so far.
Last week, SA Health updated its advice to warn those with asthma, emphysema, bronchitis, or any other form of chronic lung disease may be more vulnerable, and they should carry their reliever medication if the bloom is present, take their preventive medication as prescribed, and check their asthma management plan is up to date.
SA Health’s principal water quality adviser, Dr David Cunliffe, said authorities confirmed the presence of toxins in sea foam on 4 September, leading them to modify their health advice. He said the research showed no long-term health effects on humans.
He said they had expanded the advice to include the impacts of brevetoxins, which “does cause potential risk for asthmatics”.
While people should avoid discoloured water or foam on beaches, they should not avoid beaches altogether because of the benefits for physical and mental health, he added.
A panel of scientists told the inquiry that the current “ad hoc” approach should be overseen by a national body, while calling for early warning systems for harmful algal blooms (HABs), and improved understanding of the impact of blooms.
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Scientists also said the state and the nation were underfunded and underprepared for future destructive blooms.
Initially the Karenia mikimotoi species was the dominant species in the bloom. It is deadly to animals with gills and causes irritation to human eyes and skin, and coughing or shortness of breath.
Since the bloom began earlier this year it has evolved to contain other species and toxins have been detected in it.
Shellfish can accumulate brevetoxins to the point where ingestion could cause human illness, even when toxins are not detectable in water.
Commercial shellfish operations were forced to close earlier this year because toxins were detected. Now, brevetoxin-like substances have been found in sea foam on beaches, sparking a warning to asthmatics.
The government and a range of experts have suggested events including the 2022-23 Murray-Darling Basin floods, an upwelling of nutrients in the ocean, and a marine heatwave are among the possible causes of the bloom.
Dr Craig Styan, the president of the Australian Marine Sciences Association’s SA branch, said while there were “correlated” events, “the short answer is we don’t know enough to know”.
“We really don’t have the baseline data and we don’t know enough about the species that are in this bloom … and what drives them biologically,” he said.
His colleague, the AMSA vice-president Dr Georgina Wood, said while the cause could not be definitively named, there was a large body of evidence on the association between marine heatwaves and algal blooms, and that heatwaves would become more frequent and intense with climate change.
Asked whether more could have been done to prevent it or limit its spread, Styan said that was “unlikely”.
“There’s really almost nothing you can do, even on a moderate scale,” he said, while pointing to potential mitigation measures that “might work on a small scale”.
Clay, “bubble curtains” and algicides are among mitigation measures that have been considered.
Mike Steer, the SA Research and Development Institute executive director, said that there were three likely scenarios: the bloom could “disappear quickly as the ecosystem balances itself”; that it continues to pulsate, growing and shrinking; and that it “persists through summer and spring as the temperatures warm up”.
Chris Beattie, who is coordinating the bloom response on behalf of the government, said the pulsating option was the most likely.
He said the government was yet to announce its summer plan for the bloom but it would including protecting beach access and public health, conducting awareness campaigns, thinking about how to invest in and better understand HABs and their ecological impacts, doing trials around small-scale mitigation, and focusing on the economic impact.
“Ecological sustainability and monitoring will feature heavily in terms of any program,” he said.
