On Saturday the 11th Feb, the West Australian Seabird Rescue (WASR) received their first call about a paralysed bird with suspected Avian Botulism at Tomato Lake. Then the calls kept coming in the following days.
The City of Belmont and Department of Biodiversity, Conservation and Attractions had been notified prior to this, and said they were collecting deceased birds every morning and monitoring the lake.
Avian botulism is a naturally occurring paralytic disease, caused by a specific bacteria. It's most often seen in water birds, as the bacteria occurs mostly in wetland environments with little or no oxygen.
Birds with botulism show progressive weakness and paralysis, and results in death when untreated.
"Oxygenating and aerating the water is important to mitigate botulism outbreaks. Removing affected dead birds is important too, because the maggots eat the affected birds, then pass the paralysing bacteria onto birds again in the food chain", said Angela Radalj, who is a manager with the Western Australian Seabird Rescue.
Botulism outbreaks aren't new in Western Australia. This summer Erskine, in the City of Mandurah, have had a large avian botulism event. Their council committed to running pumps 24/7 to aerate the lake there until the weather cools, which will improve water quality.
These events often occur when water temperatures are high in Summer and Autumn, and where the water quality is poor with a lack of oxygen. Other risk factors are increased organic material in the sediment, low water levels and a high water pH.
What can you do to help?
Keep an eye out for any birds that appear weak or lame by the water's edge, and call WASR on 6102 8464, as birds don't survive without assistance.
Advocate for healthy and bio-diverse wetlands, as they support so many animals and birds.
The health of Tomato Lake can be improved by us: judicious use of fertilisers, garden and household chemicals, disposal of green waste and animal droppings to ensure they are not washed down our gutters and drains into Tomato Lake. These things affect the quality of the water, especially in the dry season when there is little rain to fill and flush the lake, improving water quality naturally.