Coastal shellfish 'colonise' ocean plastic

Scientists found coastal species of shellfish and anemones living and breeding on floating islands of garbage in the Pacific thousands of miles from home, a study revealed Monday.

Environmentalists have for years been eyeing what they call the "Great Pacific Garbage Patch" -- masses of plastic rubbish combining bottles, fishing nets and much more.

US researchers who sampled rubbish from the northeastern Pacific between California and Hawaii said they found 37 kinds of invertebrates that originated from coastal areas, mostly from countries such as Japan on the other side of the ocean.

"The high seas are colonised by a diverse array of coastal species, which survive and reproduce in the open ocean," they wrote in the study, published in Nature Ecology and Evolution.

"Coastal species persist now in the open ocean as a substantial component of a neopelagic (new, sea-dwelling) community sustained by the vast and expanding sea of plastic debris," the study said.

More than two-thirds of the items examined had coastal species on them, including crustaceans, sea anemones and moss-like creatures called bryozoans.

Scientists had not often tracked creatures surviving dispersal across entire oceans. The researchers noted that in one rare event in 2012, debris from the previous year's tsunami in Japan washed ashore in North America bearing living species.

Creatures can spread quickly by feeding on the layers of slime formed on floating plastics by bacteria and algae, the study said. Scientists must now investigate how these coastal colonists will fit into the ocean food chain.

"We found that coastal species are commonly observed on the same plastics as the native pelagic species (dwelling far out at sea), suggesting that these two communities are interacting with one another," the study's lead author Linsey Haram told AFP.

"These interactions could include competition for food and space as well as predation. More research is needed to understand whether the implications are positive or negative."

In a 2021 article, members of the same research team warned that the influx of invasive coastal species "might portend significant ecological shifts in the marine environment".

A study published in 2017 in the journal Science Advances calculated that if current production and waste-management trends continued, there would be 12 billion tonnes of plastic waste in landfills or the natural environment by 2050.

G7 energy and environment ministers declared at the end of talks in Japan on Sunday their "ambition to reduce additional plastic pollution to zero by 2040".

They said they hoped to draw up an "international legally binding instrument on plastic pollution" by the end of 2024.