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Species adapt to a plastic-supported life on the ocean waves

It is a vast monument to human carelessness: a floating layer of plastic debris more than three times the size of France. But for a growing number of organisms, the ‘‘Great Pacific garbage patch’’ is something else – their home.

A new study describes how the rubbish, which covers 1.58 million square kilometres of ocean, has been colonised by animals and plants that would normally be found on the coast. They include crabs, Asian anemones, marine worms, sea stars and sponges.

Evidence that these creatures are thriving thousands of kilometres from their usual habitats has upended the long-standing assumption that the open ocean is an impassable marine desert.

‘‘Suitable habitat now exists in the open ocean, and coastal organisms can both survive at sea for years and reproduce, leading to selfsustaining coastal communities on the high seas,’’ the researchers wrote in the journal Nature Communications.

The authors of the study have called these communities ‘‘neopelagic’’ – ‘‘neo’’ for new, and ‘‘pelagic’’ referring to the open ocean.

They exist on gyres of waste that form when surface currents drive plastic pollution from the coasts into regions of the ocean where rotating currents trap it.

There are at least five places where large amounts of plastic debris have accumulated, but the biggest is the North Pacific subtropical gyre, between California and Hawaii, with an estimated 79,000 tonnes. Much of it consists of microplastic fragments less than five millimetres wide. But it also includes larger pieces of debris such as nets, buoys and bottles.

The ability of coastal species to ride on pieces of plastic and survive in the open ocean for long periods was highlighted after the 2011 Japanese tsunami. Nearly 300 species made it across the Pacific to be washed up on the west coast of North America. Many survived on their rafts for several years.

In the latest research, computer models were used to locate and collect more than 100 tonnes of plastics and other debris. This rubbish was passed on to a team of biologists, who found coastal species not only surviving but thriving.

The results have triggered more questions: not least, what are these animals eating?

‘‘The open ocean has not been habitable for coastal organisms until now ... partly, we thought, because it was a food desert,’’ said Greg Ruiz, of the Smithsonian Environmental Research Centre.

World

en-nz

2021-12-04T08:00:00.0000000Z

2021-12-04T08:00:00.0000000Z

https://fairfaxmedia.pressreader.com/article/282286733551010

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