Methods for controlling harmful algal blooms have only been used on a small scale and a devastating Australian outbreak is likely to continue, a top US expert has warned.
Scientist Donald Anderson, who runs the US National Office for Harmful Algal Blooms, visited South Australia in August and gave evidence to a senate inquiry on the state's algal bloom in Canberra on Wednesday.
There was a possibility the bloom might disappear, but it had extended through winter and spring and that suggested it would continue for a while, Dr Anderson said.
Monitoring and awareness was one thing "but it's another thing entirely to try to suppress it or to actually kill the cells", he said.
The inquiry is taking evidence from scientists, environmentalists, government representatives, tourism and fishing industry figures and recreational bodies.
It is seeking solutions to the bloom, which has spread to an area covering 4500sq km since being identified off the Fleurieu Peninsula in March.
The most widely used method for controlling blooms in other parts of the world involved the spraying of a clay solution, but the biggest area that had been treated was only 100sq km, Dr Anderson said.
"Your bloom is many, many, many times bigger than that already, so if you tried to do something, you would be doing something no one else in the world has ever done," he said.
Dr Anderson had seen an "impressive array" of monitoring and event response programs initiated by the SA government, but he noted that virtually all of the monitoring was on beaches.
"I know you want to know if people go to beaches, but you also want to know: where is this bloom out in the gulf, where is it most dense, where is it going?
"And that involves a very different kind of monitoring with vessels, and we're proposing special new equipment that can be used on a vessel as it's moving through the water."
Since it was identified off the Fleurieu Peninsula in March, the bloom has impacted marine, estuarine and coastal waterways, killing hundreds of marine species, discolouring water and disrupting ecosystems.
The SA and federal governments have so far committed a $28 million package to respond to the bloom, including support for affected industries.
The state's algal bloom co-ordinator, Chris Beattie, told the inquiry that significant progress had been made in delivering initiatives under the package.
A beach clean-up program was fully operational, with daily operations on Adelaide beaches and targeted operations in regional areas, $1.4 million in fee relief had been given to impacted businesses and a "bubble curtain" had been installed to help protect giant cuttlefish in the Upper Spencer Gulf.
Authorities were also developing a plan for summer and details were expected to be released in early October.
The committee's report is due October 28.
