A new study from the University of Tasmania has revealed that balloons pose the biggest threat to seabirds of any type of plastic debris. Although hard plastics are more commonly ingested by marine animals, the researchers found that soft plastics are much more lethal.
The study, which was led by PhD student Lauren Roman, revealed that once a seabird had ingested a single piece of plastic, it had a 20 percent chance of death. The risk of mortality rose to 50 percent for nine pieces of plastic and to 100 percent for 93 items.
“Marine debris ingestion is now a globally recognized threat,” said Roman. “However, the relationship between the amount or type of debris that a seabird ingests and mortality remains poorly understood.”
“Among the birds we studied the leading cause of death was blockage of the gastrointestinal tract, followed by infections or other complications caused by gastrointestinal obstructions.”
Roman explained that while soft plastics accounted for just five percent of the plastic pieces ingested, they were responsible for more than 40 percent of the fatalities.
“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,” said Roman. “As similar research into plastic ingestion by sea turtles has found, it appears that while hard plastic fragments may pass quickly through the gut, soft plastics are more likely to become compacted and cause fatal obstructions.”
Study co-author Dr. Chris Wilcox said the approach taken in the study was originally developed for turtles before it was applied to seabirds.
“These two applications are the first time there has been a robust estimate of the impact of plastic ingestion on free living marine species,” said Dr. Wilcox. “This is a critical step in triggering action to address plastic pollution.”
Roman pointed out that even though soft items like balloons are more deadly, all plastics are serious threats to seabirds.
“If seabirds eat plastic their risk of mortality increases, and even a single piece can be fatal,” said Roman. “While hard plastics are less likely to kill than soft plastics they were still responsible for more than half of the seabird deaths identified in our study.”
“The evidence is clear that if we want to stop seabirds from dying from plastic ingestion we need to reduce or remove marine debris from their environment, particularly balloons.”
The study is published in the journal Scientific Reports.
By Chrissy Sexton, Earth.com Staff Writer
Image Credit: Lauren Roman