A beach in Sydney’s eastern suburbs has been closed as a precautionary measure after schools of dead fish washed up this morning leaving thousands of carcasses rotting in the warm water.
When The Southern Courier inspected Malabar Beach this morning, dead fish were strewn across the sand, rocks and in the ocean pool.
The NSW Environmental Protection Agency has confirmed it has collected samples of both the fish and water in response to the scale of the problem.
These will be sent for laboratory testing to determine the cause of death, a NSW EPA spokeswoman said.
UNSW water quality expert Stuart Khan said among the possible explanations was a possible leak from the nearby sewage treatment plant, an illegal dumping or the latest wet weather event.
Sydney Water has since confirmed there have been no recent incidents at the Malabar Wastewater Treatment Plant.
It could be a poison or the result of a build up of organic matter, Professor Khan said.
If you have a very dry period you get a lot of build up and then a big weather event washes all that organic matter into the stormwater network, he said.
Subsequent warmer weather then leads to biodegradation which causes oxygen depletion in the water.
It’s called a black water event, he said.
We’ve had the perfect circumstances for that event. It’s a well known phenomenon in rivers but it’s not so common in a marine environment but Malabar is unusual as it’s a very enclosed bay.
But he said proactive measures could be taken to avoid such environmental incidents.
When there’s a build up of leaves and you know that when a big rainfall is coming, the way to manage is to proactively clean the streets prior to the rainfall.
This month Malabar Beach was downgraded from good to poor in the latest new State Of The Beaches report.
A poor rating means the beach is susceptible to faecal pollution and microbial water quality is not always suitable for swimming, usually after heavy rainfall.
Maroubra local Shane said he saw thousands washed up along the Malabar coastline.
When I first went down I was going to have a swim in the pool but it was full of dead leatherjacket fish, he said.
They were also all along the rocks on the southern side of the bay. I’ve never seen that before and I’ve been swimming there since I was a kid.
I went to the other side of the bay but when I was in the water it was quite murky, like a brown sediment.
Obviously something’s been dumped.
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