Swimming in a sea of plastic

Over five trillion tonnes of plastic particles weighing nearly 260,000 tonnes are afloat in the world’s oceans, according to a new study. Large plastic pieces are often found on coastlines, while microplastics are mostly found in the 5 subtropical gyres. Barbara Barkhausen reports from Sydney.

Over five trillion pieces of plastic are floating in our oceans, damaging marine life and entering the food chain when ingested by fish. (Photo credit: Agustin Rafael Reyes, flickr)

Over five trillion pieces of plastic are floating in our oceans, damaging marine life and entering the food chain when ingested by fish. (Photo credit: Agustin Rafael Reyes, flickr)

The world’s oceans are full of plastic pollution, many of which are pieces smaller than five millimetres. Any form of plastic pollution in the oceans can have dangerous effects on marine animals, water quality and even people. Seals or penguins become entangled in plastic bags or fishing lines and are strangled to death. Fish, turtles and other marine animals mistake the small pieces for food and swallow them along with the toxins found in the plastic. These toxins increasingly land on our plates – and into our stomachs – each time we enjoy a plate of seafood.

Pacific Ocean becoming a dead sea

269,000 tonnes. That’s the total amount of plastic pollution afloat in the world’s oceans as calculated by researchers from the USA, Australia, New Zealand, France and Chile. The results of their six-year study, which consisted of 24 expeditions to the Pacific, Atlantic, Indian Ocean, Australian coast and the Bay of Bengal, are now published in the journal PLOS One.

It’s long been known that a huge amount of garbage is floating on the world’s oceans, much of which is found in ocean gyres. But the extent of the problem was first described just over one year ago, when an Australian sailor wrote about his journey from Australia to Japan to San Francisco and called it a “dead sea”. He caught just two fish during the 28 days from Australia to Japan, Ivan Macfadyen told his local newspaper The Newcastle Herald. But what he did encounter was a huge gyre of rubbish, which grew considerably larger after the Japanese earthquake and tsunami in 2011.

Like a plastic soup

Julia Reisser, an oceanographer at the University of Western Australia, witnessed first-hand the rubbish-strewn gyres during the expeditions that she participated in as part of the study. She told The Guardian that it was like sailing through “plastic soup” when traversing the rubbish-strewn gyres by boat: “You put a net through it for half an hour and there’s more plastic than marine life there,” she said. “It’s hard to visualise the sheer amount.”

According to the researchers, the dangers associated with marine pollution are even greater than previously understood because the problem will only get worse with time. There are two interrelated reasons for this: First, the gyres themselves act as ‘shredders’ by turning larger pieces of plastic into microplastic pieces before dispering them across the ocean. Second, the volume of plastic in our oceans is expected to increase due to the rising production of disposable plastic. Currently, only 5 per cent of the world’s plastic is recycled.

“Our findings show that the garbage patches in the middle of the five subtropical gyres are not the final resting places for the world’s floating plastic trash,” said Marcus Eriksen, another of the report’s co-authors. “The endgame for micro-plastic is interactions with entire ocean ecosystems.”

 

Photo credit: Agustin Rafael Reyes, flickr/Creative Commons

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