Invasive species cross the sea on a garbage 'Ark' as big as Texas

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The infamous Pacific garbage patch is changing the balance of life in the seas. At least 37 species of coastal creatures — worms, crabs, shellfish and the like — have colonized the Texas-sized plastic tangle, turning it into an unnatural floating habitat.

The findings, reported last week in the journal Nature Ecology and Evolution, show life's tenacity, with a variety of castaway creatures treating our trash as their own Noah's Ark. But it's not something to celebrate. It should be a wake-up call to create stronger, more binding prohibitions against using the oceans as a place to dump plastic.

Scientists worry about the plastic that's infused into the bodies of the animals living in it. That's going to go up the food chain. And they're worried that plastic garbage is becoming a conveyor belt for species that could become invasive in their new homes, wiping out other forms of life.

While it's often described as a giant island of plastic, the garbage patch is not a solid mass but a sprawling collection of plastic items from bottles to toothbrushes to fishing nets. Thanks to a persistent circulating current known as a gyre, they've collected in a single spot in the middle of the north Pacific. Other gyres have collected similar, less-famous garbage patches, including one near Easter Island in the South Pacific.

The one in the North Pacific is by far the biggest. When researcher and activist Marcus Eriksen sailed through it, he saw an endless horizon of water discolored by pollution with plastic particles.

Eriksen, founder of the environmental group 5 Gyres Institute in California, calls it "plastic smog." In a study published last month in the journal PLOS One, he and colleagues estimate that the plastic smog worldwide contains a total of 170 trillion pieces.

The 37 species found riding on the large plastic objects are likely to be just a small sample of the total, said James Carlton, a professor of marine sciences at Williams College and co-author of the paper on the animals living on the garbage patch.

The findings follow from an earlier, equally surprising discovery. Carlton had been studying invasive species along the West Coast of the U.S., when, in 2012 he started seeing giant rafts of debris ferrying coastal sea creatures across the Pacific. He and colleagues realized they were seeing debris from the tsunami that hit Fukushima in 2011.

Never before in the history of the planet has a tsunami knocked a million homes full of plastic stuff into the ocean. Year after year, the artificial rafts kept coming — boats, docks, refrigerators, housing materials, kitchen gadgets. They published their findings in Science in 2017.

Some hit land in the Pacific Northwest, and some may have swirled into the garbage patch.

Over geologic history, floating rafts of natural debris probably brought many living things to islands — lizards and frogs to Haiti, land snails to Hawaii, and even tortoises to the Galapagos. Rafting has had a profound effect on the distribution of life on the planet — and now it's happening on a drastically accelerated time scale, said Carlton. "It was a phenomenon that while classically invoked in ecology and biology and biogeography, we never really expect to see in a human lifetime."

And since the natural rafts were made of biodegradable materials, they couldn't float across vast oceans. "I told my students for 25 years in my marine ecology class that if a coastal species drifted out to sea it was a one-way trip," said Carlton. "There was nothing to eat out there, and it was not an environment in which one could survive." The plastic problem has changed that.

Carlton says the garbage might be creating a sort of hub and spoke system for redistributing species — once they get to Singapore, say, they radiate out, and if they reach Hong Kong, they may radiate to yet more beaches and islands.

Any species can become invasive — it's not something inherent in the organism but a consequence of being moved through some artificial means. Some will die in their new habitat, but others will outcompete the locals and turn a diverse ecosystem into a monoculture. Or they may carry a parasite that wipes out local species — a fate that killed most of the oysters in the Chesapeake Bay. Invasive species tend to be generalists, and wipe out more specialized life-forms, leaving us less seafood to feed the world, and less beauty and variety.

While some groups have tried scooping up the garbage patch, that's futile, said Eriksen of the 5 Gyres Institute. It's more important to stop adding to the mess — that will likely take a new international treaty that imposes penalties for discarding garbage at sea. Much of the plastic we discard goes into landfills, but in some countries, it's been cheaper to put it on barges and dump it.

And about half of the waste is fishing nets and other gear, he said. One way to clean that up would be to offer a reward for fisherman who retrieve gear others have discarded or lost.

We can still admire the tenacity of the little creatures that managed to survive in the garbage patch. But we'd all be better off if they'd stayed where they belonged.