By environment reporter Nick Kilvert
Updated Friday at 08:44
First posted Friday at 06:02
Oceanic plastic pollution is helping to spread colonising microbes to coral reefs, greatly increasing the risk of a group of coral diseases known as white syndromes, according to a new study.
The finding comes after scientists last year discovered marine animals washed out to sea during the Japan tsunami in 2011 had been surviving for up to seven years at sea on plastic rafts before washing up on the US coast.
Where plastic had come into contact with coral, the likelihood of the presence of disease rose from 4 per cent to 89 per cent — a 20-fold increase — according to the paper published in the journal Science today.
(Supplied: Jeff Tyson)
Plastic flotsam is known be used as stable vessels for algae and other organisms, including some which may carry coral-killing pathogens, study author Dr Joleah Lamb said.
"There's a disease called black-band disease — it's a thick black band that can move across the coral and cause tissue damage. It's made up of a consortia of different types of organisms, and they really like a low-oxygen, low-light environment," Dr Lamb said.
"So the plastic sitting on top of the coral can cause these micro-climates that are really wonderful for these types of bacteria to proliferate."
Dr Lamb's team ran a series of 20-metre transects, examining each piece of coral that fell along each transect line. They positively identified the presence of six different types of coral diseases.
"What's troubling about coral disease is that once the coral tissue loss occurs, it's not coming back," Dr Lamb said.
"It's like getting gangrene on your foot and there's nothing you can do to stop it from affecting your whole body."
Nearly 125,000 reef-building corals on 159 coral reef systems from Australia, Indonesia, Myanmar and Thailand were examined by Dr Lamb and her team.
They found Indonesian reefs typically contained around 25 items of plastic per 100 square metres, compared to 0.4 items over the same area on reefs in Australia.
Plastic pollution will get worse before it gets better
The researchers estimate based on current trends there will be more than 15 billion items of plastic on coral reefs by 2020.
(Supplied: Jeff Tyson)
As of 2015, more than 6.3 billion tonnes of plastic had been generated worldwide, with almost 80 per cent of that making its way into landfill or the environment.
Out of the top 10 worst plastic polluters in the world, nine are in the Asia-Pacific, according to the researchers, who say poor waste management is to blame for much of the plastics that enter the ocean.
More than 55 per cent of the world's coral reefs are also found in the Asia-Pacific.
In a move that has been applauded by environmental groups, British Prime Minister Theresa May has pledged to ban all "avoidable" plastic waste by 2042, to counter what she described as "one of the biggest environmental scourges of all time".
Greenpeace spokeswoman Alix Foster Vander Elst says more can be done by governments and corporations to combat oceanic plastics.
"Coca-Cola sells over 100 billion single-use plastic bottles a year and they're lining their pockets from creating this problem," she said.
"We can reduce, we can reuse, we can recycle, but the most powerful thing we can do is put pressure on corporations and on governments to be taking responsibility, because ultimately it ends with them."
In Australia last year, volunteers were astounded to find more than seven tonnes of rubbish on a single seven-kilometre stretch of beach on the east coast of Cape York just a year after it had previously been cleaned up.
Coral reefs are predicted to become more susceptible to disease as climate change continues to bring rising sea temperatures.
And although plastic pollution presents a huge problem for coral environments, Dr Lamb believes climate change is still the number one issue of concern.