Plastic debris at ‘Garbage Patch’ colonized by coastal species

The Great Pacific Garbage Patch, the large expanse of marine debris in the ocean, is home to new communities of coastal species, researchers have found.

A diverse array of invertebrate species that normally live in coastal waters have taken up residence on floating plastic debris northwest of the Hawaiian Islands.

Researchers found they can not only survive, but reproduce out in the open ocean.

These findings were published Monday in Nature Ecology and Evolution by a team of researchers led by the University of Hawaii at Manoa and the Smithsonian Environmental Research Center.

“This discovery suggests that past biogeographical boundaries among marine ecosystems — established for millions of years — are rapidly changing due to floating plastic pollution accumulating in the subtropical gyres,” said lead author and SERC research associate Linsey Haram in a news release.

It is a game-changer, according to Nikolai Maximenko, a senior researcher at the UH Manoa School of Ocean and Earth Science and Technology.

It means the debris washing up along mostly windward shorelines of Hawaii potentially could bring more invasive species to the isles, with unknown impacts. Historically, the isles’ fragile marine ecosystems were protected by the long distances from Asia and North America, he said.

But now there are potentially invasive coastal species living and reproducing on debris in the North Pacific Subtropical Gyre near Hawaii. A multidisciplinary team of researchers, with help from citizen scientists, analyzed 105 plastic samples from the North Pacific Gyre collected by The Ocean Cleanup during its 2018 and 2019 expeditions.

They were inspired to take a closer look at what was living in the gyre after tracking the movement of millions of objects swept into the ocean during the 2011 tsunami in Japan.

In the following years, tsunami debris with living Japanese species began washing ashore in North America and Hawaii, mostly on plastics.

In its analysis, Haram said the “FloatEco” team was surprised to identify at least 37 different invertebrate coastal species on more than 70% of the samples, which was more than triple the number of species that live in open waters.

They were not only surviving on the plastic, he said, but reproducing after colonizing new floating items, including the team’s scientific instruments.

“Our results suggest coastal organisms now are able to reproduce, grow, and persist in the open ocean — creating a novel community that did not previously exist, being sustained by the vast and expanding sea of plastic debris,” said SERC senior scientist Gregory Ruiz in the release.

“This is a paradigm shift in what we consider to be barriers to the distribution and dispersal of coastal invertebrates.”

Scientists already knew that organisms, including some coastal species, could live on marine plastic debris and “hitchhike” to another shoreline, according to Maximenko.

But they were unaware that so many coastal species, including Japanese crustaceans and sea anemones, have established communities on plastic debris in the open ocean.

“Now we are dealing with a different situation because now we have this garbage patch where new items are added continuously,” Maximenko said.

“What we discovered is inside this garbage patch, the concentration is so high that all species can spread to new items,” he said.

This only adds to the stressors on Hawaii’s ecosystem on top of others that already exist, such as global warming, sea level rise and coral bleaching.

Researchers said these findings “identify a new human-caused impact” on the ocean and document “the scale and potential consequences that were not previously understood.”

As Earth Day draws near, it also highlights the urgent need to reduce plastic pollution from getting into the ocean.

Unfortunately, other studies have found plastic pollution and its impacts on the marine environment are only expected to grow.

Plastic production and waste are predicted to exponentially increase and to reach an estimated 25,000 million metric tons of waste generation by 2050.