Shellfish toxin research helps protects lives and livelihood
The Australian seafood industry is big business, around $2.2 billion big in fact, bought into sharp focus when COVID-19 hit and high value shellfish exports to China and Japan took a dive. While the prospect of cheaper seafood dinners gave locals something to smile about there are other potential disruptors lurking in Australia’s productive coastal waters.
Fortunately, against a backdrop of rapidly changing environmental conditions, the Seafood Safety Research Group at UTS Science is a world leader in detecting and identifying an unseen threat that can paralyse both business and people.
Recently the research team, led by Associate Professor Shauna Murray, reported for the first time that paralytic shellfish toxins (PSTs) a common and pervasive neurotoxin produced by the microalgae Alexandrium pacificum, was detected at above the regulatory limit in blue mussels. The results of the study were published in the journal Microorganisms.
For lead author Abanti Barua it was a chance to delve into data collected from of Twofold Bay, a shellfish harvest area that had experienced significant bloom events of this microorganism, and other toxin producing species, from 2016 – 2018.
“The neurotoxin from Alexandrium sp.is responsible for paralytic shellfish poisoning (PSP). It’s potentially fatal in humans because it affects the respiratory system. At the very least it can cause some unpleasant effects like tingling and numbness in the lips, fingers and toes and muscle weakness,” Abanti, a PhD candidate in the UTS Faculty of Science said.
This is a very rewarding project to work on because this was a thorough and detailed study on A. pacificum isolated from NSW and it will give a good background for further investigation of this economically significant organism in NSW, she said.
The findings are important because although PSP was first reported in Australia in 1935 this is the first record of PSTs, above the regulatory limit, in south-eastern Australian aquaculture since the establishment of the NSW Shellfish Quality Assurance Program in 2005.
“The limit of 0.8 mg/kg in commercial aquaculture in NSW was set when the routine biotoxin monitoring commenced,” says A/Professor Shauna Murray, an acknowledged authority on PSTs.
“The concentrations we detected approached 10 times that level. PSTs are highly potent, you only need a few hundred cells per litre in marine waters to trigger uptake into shellfish above regulatory limits” she said.
“It was very important that, working with the NSW Shellfish Program from the Department of Primary Industries, we were able to identify this event early before any damage could be done.
“The largest toxic bloom in Australia occurred in 2012, when a shipment of blue mussels from Tasmania was found to contain PSTs above the regulatory limit by Japanese import authorities. This cost the industry around $23 million in lost revenue
“Significant levels of PST were also recorded in scallops, clams, and rock lobsters with a resulting six-month harvest closure along 350 km of the Tasmanian coastline so it’s very important to be vigilant,” Associate professor Murray said.
Vigilance coupled with on-going research as Abanti points out.
“This region of the world is a global hotspot for ocean warming. Changes such as increasing water temperature, rainfall, salinity, and nutrient availability may influence the frequency, duration and extent of future harmful algal blooms in south east Australia. More studies are required to determine the specific factors which influence A. pacificum blooms in this region, “ she says.
Research partners on the project included NSW Food Authority (NSW Department of Primary Industries), Microalgal Services, Sydney Institute of Marine Science, Senckenberg am Meer, Deutsches Zentrum für Marine Biodiversitätsforschung (DZMB)
University of Technology Sydney Higher Degree Research Fund and the Climate Change Cluster (UTS) Student Research Fund