South Australia's primary industries department is investigating the deaths of thousands of bees and freshwater crayfish at a farm south of Adelaide.
It is the second time thousands of animals have died at the site, but the Department of Primary Industries and Regions in SA (PIRSA) says there are several potential causes.
Farmer John Luckens first contacted PIRSA on December 2, when he noticed thousands of bees seemed to be dropping dead on his property near Kuitpo, south of Adelaide.
"Literally bees were falling out of the sky and the driveway was covered in dead and dying bees," he said.
"I did a quick calculation and worked out there's probably at least a thousand bees on that driveway and then in the grass beside there was probably 8,000 or 10,000 bees and I thought that was pretty unusual."
He feared that if insects were dying, his marron — a type of freshwater crayfish — would be next.
"I also then thought that then – because we had a [suspected] poisoning event from farm chemicals here a few years ago, that there might be an impact on the marron, and there was," he said.
Mr Luckens believes his marron were poisoned by aerial spraying in 2019, but neither he nor the department were able to confirm the cause.
He said in this latest incident the crayfish in two of his 30 ponds — the most elevated on his block — were affected.
"We've probably got upwards of half a ton of marron dead. That's relatively significant for us," he said.
Primary industries officers have taken water, bee and marron samples for testing and have also notified the Environment Protection Authority.
"The department … is aware of a mortality event involving marron on a farm in Kuitpo area and is currently investigating the cause including testing for infectious disease, harmful algae and chemical contaminants," a spokesperson said in a statement to the ABC.
"The results of the chemical contaminant testing might also be relevant with PIRSA's investigations into bee mortalities occurring on the same property."
'Concerned' neighbours
Mr Luckens wants the government to investigate whether chemicals from spraying of nearby vineyards may have drifted into his ponds.
The neighbouring properties have sprayed the fungicide combination Top Wettable Sulphur and Tri-Base Blue and the surfactant Viti-Wet recently, but farm managers told the ABC they used advanced equipment that limited spray drift and had not sprayed insecticides.
"We're disappointed to hear what's happened and we want to work closely with John to find out what's happened and find a solution," Mark Vella, who manages the neighbouring Hersey Wines vineyard said.
Other properties were waiting to hear more about PIRSA's investigation.
"We were concerned to hear from PIRSA today about the marron deaths on our neighbour's property," the owners of Top Note winery, Cate and Nick Foskett told the ABC via email.
"Environmental safety is something we take very seriously … however we no longer operate the vineyard and have leased it out since May 2021.
"We understand that PIRSA is conducting an investigation, so we will not be commenting further."
'May just be a coincidence'
University of Adelaide pharmacology lecturer Ian Musgrave said authorities may not be able to determine what killed the bees and the marron, especially given there were several days between nearby spraying and the testing of samples from Mr Luckens's farm.
"It's going to be quite difficult," he said.
"One of the problems is the chemicals involved will degrade in the environment.
"For example, if we're talking about lakes or ponds, the materials will be absorbed into the water, then can quite often be absorbed into the sediments in the water, drop out into the sediment, then not be detectable in the water itself."
Dr Musgrave said the culprit may also be something occurring naturally in the surrounding environment.
"The environment is pretty nasty and it kills lots of things normally. So it may just be a coincidence that we see this bee die-off at the same time as you're seeing a marron die-off," he said.
PIRSA's Rural Chemicals Operations section investigated 39 "chemical trespass" incidents in the past financial year and issued formal warnings for five.
It found more than 60 per cent of the complaints received in 2021/22 were considered to be low risks of various types, or not chemical trespass.
Mr Luckens said the state government needed to do more to protect new industries like marron farming and ensure chemical use did not affect other types of farming.
"I think most people want to do best practice and have good regulation," he said.
"Some of the processes for managing these events are not appropriate.
"We need to have new industries, particularly food industries for the future … sometimes things happen beyond the farmer's control. The government needs to have a process in place to protect their back."
