Coastal life finds a way in ‘Great Pacific Garbage Patch’
Image credit: Smithsonian Institution
Researchers from the Smithsonian Environmental Research Centre have discovered coastal organisms finding a new way of life amid floating plastic debris, by colonising plastic pollution.
Gyres of ocean plastic accumulate when surface currents drive floating plastic pollution from coasts towards regions of the ocean, rotate and trap the floating objects. There are at least five plastic-infested gyres, the largest of which is the 79,000-tonne North Pacific Subtropical Gyre between California and Hawai’i, commonly known as the “Great Pacific Garbage Patch”. This contains microplastics and floating debris such as nets, bottles, and buoys – and now coastal species.
“The issues of plastic go beyond just ingestion and entanglement,” said Dr Linsey Haram, lead author of the Nature Communications study on the adaptive coastal species. “It’s creating opportunities for coastal species’ biogeography to greatly expand beyond what we previously thought was possible.”
Haram and her colleagues call these communities “neopelagic”, referring to new communities in the open ocean. Scientists first suspected that coastal species may use plastic to survive hundreds of miles from their usual habitat after the 2011 Japanese tsunami, when almost 300 species had been found rafted all the way across the Pacific on tsunami debris.
To study the possibility of coastal life living in the open ocean, Haram worked with non-profit the Ocean Voyages Institute and oceanographers from the University of Hawai’i at Manoa. The oceanographers created models to predict location where plastic was most likely to pile up in the North Pacific Subtropical Gyre, which the Ocean Voyages Institute used to collect approximately 100 tonnes of plastic and other debris from the gyre.
Haram shipped some samples to her centre’s Marine Invasions Lab to analyse the colonial species. She discovered many coastal species – including anemones, hydroids, and shrimp-like amphipods – not only surviving but thriving on ocean plastic.
Greg Ruiz, who heads the Marine Invasions Lab, explained: “The open ocean has not been habitable for coastal organisms until now. Partly because of habitat limitation – there wasn’t plastic there in the past – and partly, we thought, because it was a food desert.”
The discovery shows that these ideas are not always true; plastic is providing a habitat and – somehow – these coastal species are finding food. Ruiz said that scientists do not yet know how, although food may be accessible when debris floats into existing “hot spots” in the gyre or because the plastic itself is a rich enough ecosystem to attract more food sources.
Now, scientists have another change to reckon with: how these “coastal rafters” could shake up their new environment. The open ocean has plenty of its own native species which also colonise floating debris; the arrival of unfamiliar species could disrupt ocean ecosystems that have remained undisturbed for millennia. There is also the question of whether these coastal species could be carried to new coastlines and become invasive species elsewhere.
“Coastal species are directly competing with these oceanic rafters,” said Haram. “They’re competing for space. They’re competing for resources. And those interactions are very poorly understood.”
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