Thousands of mysterious, spherical black balls have washed up on beaches in Sydney’s eastern suburbs – and preliminary test results suggest they are tar balls.
Randwick council closed Coogee beach on Tuesday afternoon after lifeguards discovered the golf ball-sized objects. The council also closed nearby Gordons Bay on Wednesday afternoon, stating “more mysterious, sphere-shaped debris” had been found washed up.
On Thursday, authorities said they had closed five more beaches, including Bondi, Tamarama, Bronte, Clovelly and the northern end of Maroubra, bringing the total number of beaches closed to seven.
According to Randwick council, preliminary testing shows the balls are a hydrocarbon-based pollutant, consistent with the makeup of tar balls.
Here is everything you need to know.
What is a tar ball?
A tar ball is a blob of a petroleum which has travelled through the ocean and collected debris, says Louise Morris, the oil and gas campaign manager at the Australian Marine Conservation Society.
“It is a fossil fuel pollution which has attached itself, because it is super sticky, to whatever it comes in contact with that is floating in the ocean.”
After a spill from a rig, for example, petroleum is often washed in waves and currents, making it condense and coagulate, Morris says. “The more it keeps gripping on to other substances, it solidifies and condenses.
“Part of that process of washing through the ocean means that they form a spherical shape.”
Some tar balls fall to the bottom of the ocean, while others containing more air will float.
It is not unusual for tar balls to end up on shores. The Gulf of Mexico, which has natural oil seeps, commonly has tar balls – “which often look a little bit more like pancakes” – wash up on beaches, says Dr Sharon Hook, CSIRO principal research scientist.
“The thing is, you don’t normally get hundreds of them all at once.”
Is this case unusual?
Some experts were initially uncertain about whether the objects were tar balls.
One of the unusual things was that “we got so many all of a sudden”, Hook says. Because the balls are so uniform and round, andhave only been deposited in a small environment, it “may mean it probably happened close”.
“But anything could happen,” she says.
Oil spills usually stain sand and leave a sheen on the surface of water, Hook adds.
Port authorities said no oil spills have been self-reported by any vessel operators.
“It’s not impossible that it happened without this, but it is unusual,” Hook says.
What impact could the balls have on the environment?
For the hundreds of tar balls found on the shore, there would be “at least half of that again in the ocean”, Morris says.
That could be a problem for marine life. Coogee is home to various shark species and is a humpback whale migration zone.
“If there are tar balls floating around below the ocean surface, or some of them have just sunk to the bottom, all of our marine life and a whole food ecosystem is impacted.”
“Tar can be sticky,” Hook says. “We’ve all seen the heartbreaking pictures of birds and other animals coated in oil after a spill; we wouldn’t want them to come in contract with this and be coated with a substance that is either toxic or destroys the weatherproofing of their feathers.”
If animals ingest the debris, that could block their stomach and stop them digesting food.
Morris’s concern is less about the volume of debris but how long tar balls last.
“Because it is a petroleum product, and it is probably attached to a lot of plastic, this is decades if not hundreds of years of pollutants that can be existing and disintegrating and changing shape in our marine environment.”
What about the risk to humans?
Hook says authorities were right to close the beaches.
Tar balls are full of carcinogenic chemicals, she says. “You certainly would not want your kid to be planted making a sand castle next to it.”
Morris says this mystery deposit is a reminder to government.
“We need to stop all new fossil fuel developments and … clean up the existing rigs and oil ships that are in our ocean already,” she says.
“We know the pollution is happening. It’s turned up on our beach, which is rare, and it’s a good reminder that urgent action is needed to clean up our climate and our oceans.”
