Image: City of Onkaparinga
South Australia’s devastating algal bloom has highlighted the impact ocean disasters can have on coastal communities, but new research warns marine heatwaves themselves could pose an even broader threat to human health.
Researchers from Adelaide University and the University of Hong Kong are calling for marine heatwaves to be recognised as a major public health issue, with a new paper warning that the effects of extreme ocean warming can extend far beyond the loss of marine life and declining fish stocks.
Published in Nature Sustainability, the research outlines how prolonged periods of unusually warm ocean temperatures can trigger a chain reaction that affects people’s physical and mental wellbeing.
From intensifying storms and reducing seafood supplies to disrupting livelihoods and contributing to anxiety and grief, the researchers say the health impacts of marine heatwaves have been largely overlooked.
Lead author Dr Laura Falkenberg, from Adelaide University’s School of Physics, Chemistry and Earth Sciences, said, “Marine heatwaves are no longer just recognised as an environmental issue; they are increasingly also perceived as a human health issue.
“Our paper highlights that these events can influence people’s health in many different ways, both directly and indirectly. They can intensify storms and atmospheric heatwaves, affect the availability and safety of seafood, disrupt livelihoods and contribute to anxiety, grief and other mental health impacts in communities that depend on healthy oceans.”
The researchers point to Hurricane Otis in Mexico in 2023, which caused an estimated US$15 billion in damage, and Typhoon Doksuri, which affected more than two million people across Asia, as examples of extreme weather events linked to marine heatwaves.
Closer to home, South Australia’s 2025 algal bloom also demonstrated how changes in marine environments can ripple through coastal communities.
The toxic bloom was associated with respiratory irritation and asthma, as well as significant emotional impacts, including grief, frustration, depression and eco-anxiety among people living in affected areas.
Marine heatwaves are becoming more frequent, longer lasting and more intense as the climate warms. They have already been linked to mass marine die-offs, widespread coral bleaching, harmful algal blooms and major disruptions to fisheries and aquaculture.
Extreme ocean temperatures can contribute to more intense weather systems, increasing the risk of injury, death and displacement caused by storms and flooding.
Harmful algal blooms can also contaminate seafood, creating potential health risks, while declining fish stocks and reduced seafood production could threaten food security for communities around the world.
For coastal communities, there is another less visible impact. The researchers say watching marine ecosystems deteriorate, particularly for people whose livelihoods, culture and identity are closely connected to the ocean, can contribute to significant psychological distress.
“Many people rely on healthy oceans not only for food and income, but also for recreation, cultural
identity and their overall sense of wellbeing,” Dr Falkenberg said.
“When marine ecosystems suffer, the impacts ripple through communities. We are seeing increasing evidence that these changes can contribute to eco-anxiety, grief and other mental health challenges, particularly for people who feel deeply connected to the marine environment.”
The researchers are now calling for governments and public health agencies to treat marine heatwaves more like land-based heatwaves, including incorporating marine heatwave forecasts into public health planning.
They also want health impacts to be considered in marine and coastal management decisions, alongside greater collaboration between ocean scientists, health authorities and resource managers.
“Recognising these health impacts is the first step towards better protecting communities,” said Dr Falkenberg.
“If we only respond after disasters occur, we will continue to experience greater impacts than if we had acted proactively. By understanding the links between ocean health and human health, we can develop better policies that protect both people and the marine ecosystems they depend on.”
The research, Recognising the human health impacts of marine heatwaves, has been published in Nature Sustainability.
