Plastic waste: Balloons are the deadliest

Sea birds often die when swallowing soft plastic parts

This petrel has perished from swallowed balloon remains. © Lauren Roman
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Deadly Food: Even a single swallowed piece of plastic can kill a bird, reducing its chance of survival by 20 percent, a study reveals. Soft plastic parts, such as foils or balloons, are particularly dangerous: they clog the bowels of the seabirds and kill every five of them, according to researchers.

Our plastic waste now lapses the entire marine environment - from the Arctic to the South Seas and from the garbage swirls on the sea surface to the deep sea. For marine animals and birds looking for food in the ocean, this is a deadly danger. Because the plastic can clog their guts and also often contains toxins. Biologists estimate that 90 percent of all seabirds have ever had plastic in their stomach. After all, many plastics in the sea evidently produce an almost irresistible fragrance for birds.

But how big is the danger for the affected birds? And which plastic parts are particularly deadly for those? To find out, Lauren Roman from the University of Tasmania in Hobart and her team evaluated the records of 1, 733 dead seabirds from 51 species. They examined whether the animals had swallowed plastic and what shape and texture these plastic parts had.

Even a swallowed part can be fatal

The result: 32 percent of seabirds had at least one piece of plastic in their digestive tract at the time of death. "The amount ranged from one to 40 parts per bird, " the researchers report. However, the plastic was not always the clear cause of death: 27 percent of the birds had died as a result of the swallowed plastic parts - mostly due to a blockage of the digestive tract, as Roman and her team noted.

From the data, the researchers determined the specific threat to the sea birds. According to this, mortality increases by only 20 percent with just one swallowed plastic part. "Every single part can therefore be deadly for the birds, " says Roman. On the other hand, if the birds have nine parts in their digestive tract - which is quite likely - then their risk of death increases to 50%. display

Balloon remains often lead to deadly blockages, here in a gray-headed albatross. Lauren Roman

Soft plastic is the deadliest

Interestingly, although nearly 95 percent of the chipped waste consisted of hard plastic, only half of it was fatal. Instead, soft plastic remnants such as foils, balloons, rubber bands or foams proved to be a particular danger. "Although this soft plastic accounted for only five percent of the choked-off parts, it accounted for 40 percent of deaths, " says Roman.

Especially deadly are apparently balloon bladders: "They killed about one of seagulls that had taken these parts, " said the researcher. Similar investigations in sea turtles suggest that this is due to the poorer passage of soft plastic through the intestine: "Hard plastic fragments pass it relatively smoothly, while soft plastic tends to clump together and then fatal clogs causes, "explains Roman. "Death by a soft plastic part is therefore 32 times more likely than by a hard plastic part."

Confusion with squid

The problem here: Just the water-wafting films and balloon scraps are similar to a popular prey of many sea birds: the squid. Due to this likelihood of confusion, the soft plastic poses a particularly great danger to the animals, as the study also showed: Among the sea birds studied, there were particularly many species of birds that have squid as their main food.

"The situation is clear: If we want to prevent sea birds from dying on swallowed plastic parts, then we have to remove the waste from the marine environment or at least prevent another Vermülllung - especially what balloons and Films, "says Roman. (Scientific Reports, 2019; doi: 10.1038 / s41598-018-36585-9)

Source: University of Tasmania

- Nadja Podbregar