Seabirds like albatrosses belong to the most threatened bird group in the world. Coincidentally, this group of birds (Procellariiformes) also ingests the highest amount of human garbage found in oceans around the world.
At this very moment, 250,000 tonnes of garbage is drifting through the world’s oceans and threatening marine wildlife who mistake it for food. The discarded balloons in the mix are 32 times more likely to kill a seabird than hard plastics. With nearly half of all seabirds experiencing population declines and more than one-quarter threatened around the world, it’s predicted that in the next three decades, 99 percent of all seabird species will have ingested trash drifting in the ocean.
"Marine debris ingestion is now a globally recognized threat," said study author Lauren Roman in a statement. "However, the relationship between the amount or type of debris that a seabird ingests and mortality remains poorly understood.
To analyze this relationship between the amount or type of plastic debris that a seabird eats and how likely it is to die from it, researchers conducted autopsies on more than 1,700 seabirds belonging to 51 different species. They found that one in five seabirds eating just one piece of plastic will die, but that number jumps up to half for those eating nine pieces and 100 percent for those who eat 93 pieces of plastic. In total, researchers collected more than 2,600 plastic items. Hard plastic accounted for 92 percent of all items collected, followed by soft plastics, such as those used in packaging (2.1 percent), and balloon fragments (2 percent).
“Although soft plastics accounted for just 5 percent of the items ingested, they were responsible for more than 40 percent of the mortalities," said Roman. “Balloons or balloon fragments were the marine debris most likely to cause mortality, and they killed almost one in five of the seabirds that ingested them.”
Roman says soft plastics are more likely to become compacted, unlike hard plastics that can pass “quickly through the gut.” Once stuck in the gastrointestinal tract, these plastics create blockages that can lead to infections and other complications caused by such obstructions.
“These findings have significant implications for quantifying seabird mortality due to debris ingestion, and provide identifiable policy targets aimed to reduce mortality for threatened species worldwide,” wrote the authors in Scientific Reports.