Balloons and balloon fragments are the deadliest kinds of marine pollution for seabirds, killing almost one in five birds that ingest the soft plastic, according to a new study published in the journal Scientific Reports.

The research, conducted by scientists at the University of Tasmania, examined the cause of death of 1,733 seabirds, 32 percent of which had ingested marine debris. Hard plastics — items like LEGO bricks or straws — accounted for 92 percent of all items ingested. Soft plastics — including packaging, rubber, foam, rope, and balloon fragments — accounted for just over 5 percent of items ingested, but were responsible for 42 percent of seabird deaths. Balloon fragments, specifically, composed just 2 percent of ingested plastic, yet the scientists found that if a bird ingests a balloon or balloon fragment, it is 32 times more likely to die than if it ingests a hard plastic fragment.

“A hard piece of plastic has to be the absolute wrong shape and size to block a region in the birds’ gut, whereas soft rubber items can contort to get stuck,” Lauren Roman, a marine scientist at the University of Tasmania and lead author of the new study, told ABC News in Australia.

Some scientists have predicted that by 2025, the cumulative amount of plastic in the ocean could reach 250 million tons. Some 180 marine animals — including mammals, birds, reptiles, crustaceans, and fish — have been found to ingest plastic. Even some of the smallest creatures in the deepest parts of the ocean have plastic in their stomachs.

Seabirds, which represent a shrinking portion of bird species around the globe, have been shown to consume large amounts of plastic waste, mistaking it for prey such as squid and small fish. Roman and her colleagues say their research could be used to shape future waste management strategies, as well as seabird conservation programs.

—Emma Johnson

