Traces of the banned pesticide DDT and the man-made PCB chemicals have been found in dolphins in Gladstone Harbour, in the Whitsundays,Townsville and the Fitzroy River near Rockhampton, a long-time dolphin researcher said.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
Daniele Cagnazzi, a post-doctoral researcher with Southern Cross University's Marine Ecology Research Centre, has published his findings on contaminants found in dolphins.
Dr Cagnazzi said his findings suggest the chemicals were washed from fertilised fields and have been slowly absorbed by dolphins at the other end of the food chain.
"During the floods, all the sediment gets washed from the grazing land and the agricultural land and ends up in the coastal waters," he said.
"And it is likely to still have some herbicides and pesticides inside and they become available for other animals to absorb further up the food chain."
"This is a widespread issue that needs to be further investigated," he said.
His findings are part of one of Australia's longest-running dolphin research projects, the Capricorn Cetaceans Project (CCP).
The project has been looking at the long-term conservation and management of inshore dolphins – the humpback and snubfin dolphins - from Central Queensland in Central Queensland since 2006.
Dr Cagnazzi – speaking while collecting further biopsies from dolphins in Gladstone Harbour on Wednesday – said biopsies on 240 dolphins had provided the data.
"We've found high levels of PCB's for example and we still found – at lower levels – we found some DDT," Dr Cagnazzi said.
"For PCBs some animals were at very high levels, potentially dangerous for their health," he said.
Dr Cagnazzi said DDT levels in the dolphins varied widely.
"For DDT, it was mostly at low levels - not dangerous for the animals - but some animals were at high levels," he said.
PCBs, or poly-chlorintaed bi-phenyls, are man-made chemicals that comes from lubrication fluids and insulation. Sale of PCBs was "severely restricted" in the 1970s.
DDT is a synthetic pesticide that was banned from sale in 1987.
Biopsies were taken from 155 humpback and 85 snubfin dolphins from Central Queensland, Moreton Bay, Great Sandy Strait, Whitsundays, the Fitzroy River near Rockhampton and Townsville.
In 2006 DDT was also been found in crabs in the Burnett River catchment near Bundaberg and Bargara.
Dr Cagnazzi said researchers also found high levels of hydrocarbons in dolphin biopsies.
The researchers have also found evidence of viruses washed downstream impacting the dolphins after the 2011 floods.
Viruses – including taxoplasmosis - are washed down from the upper river into the bays after floodwaters drain from the fields, Dr Cagnozzi said.
Toxoplasmosis is a parasitic disease and begins with mild flu-like symptoms.
"Sometimes the viruses just weaken the dolphins enough to make the dolphin unable to feed," he said.
The project is investigating the reasons behind a drop – and subsequent slow recovery - in the populations of the two species; the humpback and snubfin dolphins.
Dr Cagnazzi said there were around 150 humpback and 150 snubfin dolphins before the 2011 floods around Central Queensland.
Their populations dropped to around 100 after the 2011 floods and have now increased to around 120.
Humpback and snubfin dolphins have a small gene pool, meaning they rely on their own populations for breeding, Dr Cagnazzi said.
He said this made these Central Queensland populations ever more vulnerable.
The research is partly funded by the Gladstone Ports Corporation and Southern Cross University.
