Toxic algal blooms are of increasing concern in Australia, with South Australia’s coastal waters feeling their impacts in the forms of damaged marine environments and widespread fish deaths since early 2025.

But what happens when the crustaceans and fish that encounter the toxins end up on our plates?

Dr Cherono Kwambai from Murdoch University’s Algae Innovation Hub developed and validated an analytical method to detect the toxins in the most popular seafood crustacean and successfully trialedmethods of reducing the toxin load.

The results of this research will help to inform best practice for seafood storage and preparation, bloom treatment, and toxin detection – which are critical to both environmental and public health.

Dr Kwambai’s research focused on the toxic bloom, Alexandrium Minutum, and she quickly realised its impact could be hazardous not just ecologically, but also for public health. 

The Blue Swimmer Crab is the most harvested edible crab species in Australia – with 500-800 tonnes harvested commercially per year, and around the same numbers recreationally.

As toxins from the bloom make their way through underwater ecosystems, they enter the bodies of aquatic animals such as the Blue Swimmer Crab. Historically, the toxin has been difficult to detect.

“I found that these toxins accumulate exclusively in the hepatopancreas, a vital organ found in anthropods and molluscs,” Dr Kwambai said.

Upon validating her method of detection, Dr Kwambai trialed methods of both reducing the toxin upon harvesting, and the removal of toxic Alexandrium cells from water.

“I also examined the effects of cooking and freezing on toxin levels, discovering that freezing and thawing can significantly reduce concentrations.”

Dr Kwambai conducted small-scale controlled trials using a PAC-modified clay on the bloom, which achieved up to 100% removal within two hours at low concentrations.

The efficiency of this modified clay in saline water slurry offers significant cost and operational benefits.

Dr Kwambai said this combined with the clay’s minimal risk to organisms living along the floorline of underwater environments supported the case for larger-scale, in-situ testing.

She added that this research gave her the chance to contribute practical solutions to real-world problems.

“I wanted to bridge the gap between academic knowledge and everyday application – turning science into action that safeguards ecosystems, supports sustainable fisheries.”

Dr Kwambai’s PhD was co-funded by the Department of Biodiversity, Conservation and Attractions, the Department of Primary Industries and Regional Development and the Department of Health.

The results of this work will help to refine future research focuses across WA.

Primary supervisor and head of the Algae Innovation Hub Professor Navid Moheimani said this study showed what could be achieved when research was focussed on locally relevant environmental challenges.

“Strong collaboration with local government is essential,” Professor Moheimani said.

“They are key to implementing practical interventions and ensuring that innovative science leads to meaningful outcomes for our coastal ecosystems and industries.”