Signs of algal bloom ‘clearing up’ as likely cause revealed
Latest data is showing the Karenia causing the state’s algal bloom could be disappearing from metropolitan waters, as a new study indicates the likely species producing harmful brevetoxins.
Latest results from the South Australian Algal Bloom Water Testing and Monitoring Program on November 4 showed that there was zero Karenia detected at 14 out of 21 metropolitan onshore sites.
In the state government’s weekly algal bloom update, it said this was a sharp reduction compared to results from October 21, when there were six sites recorded with more than a million cells of Karenia per litre.
The positive news comes as new research led by University of Technology Sydney professor Shauna Murray indicated that algal species Karenia cristata was the source of brevetoxins within the algal bloom.
Today’s update from Environment Minister Lucy Hood MP and South Australian Research and Development Institute executive director, Professor Mike Steer, also comes as the State’s Algal Bloom Committee hears more evidence this afternoon.
Among the areas with zero levels of Karenia were the Port River Outer Harbour Boat Ramp, West Lakes Inlet, Largs Bay Jetty, Grange Jetty, West Beach Boat Ramp, Glenelg Jetty, Hallett Cove and Onkaparinga Rowing Club.
According to the state government, the remaining seven sites recorded low or background levels of Karenia, ranging from 50 to 9900 cells per litre.
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“We do remain cautiously optimistic at these results, which are very similar to the ones we received last week,” Environment Minister Lucy Hood MP said.
South Australian Research and Development Institute (SARDI) executive director Professor Mike Steer said that the testing results “invite a level of optimism that the bloom is showing signs of clearing up”.
However, he cautioned about drawing any concrete conclusions before other evidence was considered.
Steer said that SARDI was still seeing concentrations of Karenia cells in deep offshore water and was continuing to sample that on a regular basis to see what impact it has on SA’s coastal environment.
He also said that there were some counts that remained moderate to high in the Southern Fleurieu, which SARDI was monitoring with a greater level of frequency.
SARDI would also continue to monitor Gulf St Vincent, where offshore sampling has also detected Karenia in the deeper waters, with levels ranging from about 5200 to 292,000 cells per litre at testing sites.
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The November 4 results show zero or low levels of Karenia across the Eyre Peninsula, Yorke Peninsula and much of the Fleurieu Peninsula.
“So, despite some positive news, particularly along our metropolitan coast, there are a few other areas of interest where we’re ramping up our surveillance and trying to get a greater understanding of the dynamic over the next couple of weeks,” said Steer.
Steer said that SARDI expects there is still a lot of chlorophyll in the water, meaning there were a lot of other non-harmful algal species in SA’s coastal system.
He said that if there were strong onshore winds in November, SA would continue to see foaming events, which would contain non-harmful organic material.
Asked about the new research on Karenia cristata, Steer said that it showed the species could be the main culprit, but said the research still needed to go through a peer-review process before being published.
“We do realise that at the beginning, it was initially considered that Karenia mikimotoi was the predominant species. But, as we learned, we started to see there was a greater level of complexity in that community,” he said.
“What this research has actually done is been able to molecularise, or genetically identify with a greater level of accuracy, that species … and Karenia cristata is the most dominant species and the likely culprit that is producing the brevetoxins that we’ve been detecting in our shellfish production for months.”
It comes as InDaily reported yesterday that the Environment Protection Agency (EPA) missed an entire year of water testing in South Australia because a key staff member was on leave.
The state’s inquiry into the harmful algal bloom heard on Monday that the EPA did not undertake baseline water testing in 2023 after River Murray floodwaters gushed into the sea near Goolwa.
EPA chief executive Jon Gorvett also told the inquiry that bureaucratic hurdles have prevented them from undertaking mitigation trials to protect against future algal bloom events.
“There is a process which we have been going through with the federal bureaucrats,” he said.
“I am confident our team are working as quickly as they can to navigate the various different technical, scientific and bureaucratic hurdles to get to that point.”
