Animals ingest plastics in varying forms, and soft plastics often cause more gastrointestinal blockages than hard plastics. These blockages are a leading cause of mortality among seabirds. Balloons that end up in the sea or wash ashore pose a lethal threat that was not fully understood before. Balloons are widely used at festive events, yet they carry significant environmental costs for wildlife.
The most recent findings reinforce a 2019 study conducted by a doctoral student with IMAS-CSIRO and published in Scientific Reports. The study showed that while hard plastics constitute the majority of ingested litter, they are less likely to be fatal than soft plastics, such as balloons.
“Ingestion of marine debris is a recognized threat around the world,” noted the researcher. “However, the connection between the amount or type of plastic litter ingested by seabirds and the deaths it causes remains poorly understood.”
“Among the birds studied, the primary cause of death was obstruction of the gastrointestinal tract, followed by infections or other complications from such blockages.”
A seabird eating one piece of plastic has about a 20% chance of death, increasing to 50% with nine pieces and reaching 100% if 93 pieces are swallowed.
Responsible for more than 40 percent of deaths
“Soft plastics accounted for only about 5 percent of the substances ingested by birds, yet it was responsible for more than 40 percent of deaths,” the researcher explained.
“Balloons or balloon fragments are the marine litter most likely to cause death, and they were linked to nearly a fifth of the seabirds that swallowed them,” the scientist added.
“While hard plastic fragments can pass through the gut relatively quickly, similar research on sea turtles shows soft plastics are more prone to causing deadly blockages,” the researcher said.
CSIRO co-author Chris Wilcox noted that the approach used in the study was first developed for turtles before applying it to seabirds.
“These two applications mark the first robust estimates of the impact of plastic ingestion on marine wildlife,” Wilcox stated. “This is a critical step to trigger action to address plastic pollution.”
The researchers emphasized that soft objects like balloons pose a greater risk, but all plastics present a deadly threat to seabirds.
“The evidence is clear: to prevent seabird deaths from ingesting plastic, efforts must focus on reducing or eliminating marine litter around them, especially balloons,” the researchers concluded.
Reference: Nature Scientific Reports, 2018.
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