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Dozens of dead, paralysed or strangely acting kangaroos have been observed near a beach in South Australia where a microalgal bloom has killed sea life and made surfers feel sick.
An expert in wildlife disease has called for the state government to investigate the deaths since the only animals that appeared affected were near the algal bloom.
Victor Harbor surfer Anthony Rowlands visited Tunkalilla Beach, west of the town, late on Thursday evening and saw at least eight dead kangaroos on and near the path to the beach.
He said there were probably many more in the grassy areas above the beach.
"There were a couple of joeys standing by themselves and a couple more standing near the corpses," he said.
A man on a beach holding a dead weedy seadragon
Anthony Rowlands has spent much of the past two weeks monitoring Fleurieu beaches. (ABC South East SA: Caroline Horn)
Mr Rowland said he also saw between 10 and 15 kangaroos in severe distress, unable to stand and only able to move their heads or paws.
He also observed a mob of approximately 30 kangaroos surrounding the worst-affected animals and said many of them also seemed to be acting strangely and did not immediately move away when approached, as he would normally expect wild kangaroos to do.
"I approached the group and then two or three just stacked it and couldn't get up and so I stopped walking towards the group because I didn't want them to all stress out,"
he said.
A dead kangaroo on the sand
One of the dead kangaroos seen at Tunkalilla Beach on the Fleurieu Peninsula. (Supplied: Anthony Rowlands)
The Environment Protection Authority said on Monday that it had identified the species Karenia mikimotoi as the cause of a microalgal bloom on the south coast of the Fleurieu Peninsula that had killed fish and other marine life and had left surfers feeling sick since March 15.
Previous deaths blamed on grass
The presence of a smaller number of dead and sick kangaroos and two dead seals in the area near Tunkalilla Beach was reported by ABC Radio Adelaide a week ago.
Following the report, National Parks and Wildlife (NPWS) rangers were sent to the area.
A large number of dead sea dragons arranged in lines on brick pavers
Mr Rowlands has collected nearly 50 dead woody and leafy sea dragons from affected beaches.
A spokesman for the Department for Environment and Water told the ABC later that day that early indications were that the kangaroos may have succumbed to phalaris grass toxicity, after eating the pasture because of low food availability and the ongoing dry conditions.
Kangaroos that eat the grass — also known as canary grass — can develop a condition known as the "phalaris staggers", which causes head tremors, a loss of co-ordination and collapse.
the carcass of a dead kangaroo laying on yellow grass
A kangaroo found dead inland from Tunkalilla Beach last week. (Supplied)
Call for investigation
Wayne Boardman lectures in wildlife and conservation medicine and veterinary biosecurity at the University of Adelaide.
Dr Boardman said the government needed to investigate the deaths of the kangaroos thoroughly and that his university could be called on to perform necropsies if necessary.
"You're seeing deaths of fish and you're seeing clinical signs in humans associated with going down there, coughing and sneezing and so on. And you're then seeing animals down there that are not doing well.
"It points to the fact that you should be investigating it and you can't just dismiss it by doing a cursory view of it and saying: 'Oh, it could be phalaris staggers.'"
A man with glasses smiles. Behind him is a bush setting.
Wayne Boardman has previously researched plants and toxicity in kangaroos and other wildlife. (ABC South East SA: Caroline Horn)
Dr Boardman said the Department of Primary Industries and Regions should be mapping the location of the sick and dead kangaroos and investigating if any other deaths were occurring on the Fleurieu Peninsula.
"It does not make any sense to me that if they've not seen any phalaris staggers across the rest of the Fleurieu, or indeed in South Australia, you would be hard pressed to say it was phalaris staggers when it's not been seen elsewhere," he said.
"There's a lot of pressure being put on our environment from climate, from degradation of lands, run-offs, toxins and so on, and we need to know what is going on.
"It's important to find out for the future."
The Department of Primary Industries and Regions said its animal biosecurity team had attended Tunkalilla Beach to investigate reports of sick and dead kangaroos.
It said the team humanely euthanased about 50 kangaroos that were showing severe neurological symptoms and were in distress.
Samples have been collected from the kangaroos for a disease investigation.
Water samples were also collected from the creek, a brackish lagoon and the ocean for testing.
The department has not received any other reports of large numbers of sick or dead kangaroos.
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