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Environment Protection Authority

Algal toxins most likely cause of water bird deaths in Blackwall

Media release: 19 September 2016

The NSW Environment Protection Authority (EPA) has concluded that algal growth and associated toxins in stormwater are the most likely cause of bird deaths at Blackwall, on the Central Coast.

The EPA along with researchers at Taronga Conservation Society Australia, Central Coast Council and other government agencies conducted detailed scientific investigations to understand what caused the deaths of dozens of pelicans and ducks in the Blackwall area after the issue was first raised by a local pelican researcher concerned about bird deaths in the area.

Water sampling undertaken by the EPA and Central Coast Council since 2014 ruled out potential causes of bird deaths, including pesticides and heavy metals. 

Autopsies conducted by Taronga on deceased birds also eliminated viral, parasitic and bacterial infections or avian botulism as possible causes of death. 

Veterinary pathologists from Taronga’s Australian Registry of Wildlife Health identified what appeared to be algae in the gut of deceased birds collected from the Blackwall site. Subsequent testing found high levels of a cyanobacterial toxin, which is associated with blue-green algae.

The EPA also sought expert advice from University of Tasmania’s Professor Gustaaf Hallegraeff, an internationally recognised expert in harmful algal blooms. Professor Hallegraeff concluded that algal toxins were the probable cause of the recent bird deaths and he noted the toxin could be ingested by birds when they come into contact with blue-green algae surface scums.

Based on the evidence available and Professor Hallegraeff’s advice, the EPA has concluded that recent bird deaths at Blackwall are likely to be linked to algae and associated toxins in stormwater, particularly at the stormwater canal directly north of Alpha Road.

NSW EPA Director North Branch Adam Gilligan said the joint efforts from Central Coast Council, Office of Environment and Heritage, Taronga Conservation Society Australia, University of Tasmania, the Department of Primary Industries, National Parks and Wildlife Service and community members, had been invaluable in the investigation.

“The EPA has been involved in this issue since 2014 and now, with co-operation across multiple organisations, steps can be taken towards a remedy,” Mr Gilligan said. 

“Based on this new information, the EPA has advised Central Coast Council to investigate and, with input from relevant experts, implement actions at the Blackwall site in order to minimise  opportunity for algal growth and prevent  birds coming  into contact with algae.”

Contact: Public Affairs

Page last updated: 19 September 2016