Scientists find coastal marine species living among trash in open ocean

Marine creatures and plants typically found in coastal regions have found new ways to survive in the open ocean by colonizing plastic pollution, scientists say.

A new study, published on Thursday in the journal Nature Communications, has found coastal marine species inhabiting floating trash after catching a ride to the North Pacific Subtropical Gyre, also known as the “Great Pacific Garbage Patch,” hundreds of miles out to sea.

"The issues of plastic go beyond just ingestion and entanglement," Linsey Haram, lead author of the article and fellow at the American Association for the Advancement of Science, said in a news release. "It’s creating opportunities for coastal species’ biogeography to greatly expand beyond what we previously thought was possible."

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Gyres of plastic form when currents deliver plastic pollution from the coasts into regions where rotating currents trap the floating objects in place and they can accumulate over time. There are at least five plastic-infested gyres around the globe. The North Pacific Subtropical Gyre, located between California and Hawaii, has the most floating plastic with an estimated 79 million kilograms floating in a region over 1.5 million square kilometres.

Until now, confirmed sightings of coastal species on plastic in the open ocean were rare. Scientists first began suspecting these species could use plastic to survive out in the ocean for long periods of time after the 2011 tsunami in Japan when they discovered that nearly 300 species had rafted all the way across the Pacific on debris over the course of several years.

"The open ocean has not been habitable for coastal organisms until now," Greg Ruiz, a senior scientist with the Smithsonian Environmental Research Center and co-author of the study. "Partly because of habitat limitation—there wasn’t plastic there in the past—and partly, we thought, because it was a food desert."

Plastic is providing the habitat, but Ruiz says scientists are still trying to figure out the species are finding food, such as whether they drift into hot spots or if the plastic acts like a reef and attracts nutrition sources.

Now that they know coastal species can exist far into the ocean, scientists are wondering how their presence could impact an environment already inhabited by sea creatures who also use the plastic as a habitat.

"Coastal species are directly competing with these oceanic rafters," Haram said. "They’re competing for space. They’re competing for resources. Those interactions are very poorly understood."

The discovery also raises questions about the possibility of coastal species invading regions where they are foreign. This has already been seen with tsunami debris from 2011 that carried organisms from Japan to North America.

"Those other coastlines are not just urban centres,” Ruiz said. “That opportunity extends to more remote areas, protected areas, Hawaiian Islands, national parks, marine protected areas."

The study authors say they still don’t know how common these ocean communities of coastal species are, if they can continue to sustain themselves or if they exist outside of the North Pacific Subtropical Gyre. But with the world’s increasing dependence on plastic and more frequent storms as a result of climate change, they expect more plastic will be pushed out into the sea and for colonies of coastal species in the ocean to grow.