While we know that a huge amount of plastic waste is building up in the oceans, what we don’t know a lot about is where it ends up, and what exactly it means for marine ecosystems. After studying the stomach contents of thousands of animals, scientists at Cardiff University have come up with a way of predicting the size of the biggest pieces of plastic different creatures can consume, which could inform the risks different types of waste pose to species around the globe.
While the effects of plastic waste on marine animals are largely unknown, scientists in the field are uncovering more details around why they consume it and the risks it might pose. A 2016 study, for example, found that seabirds gobble up plastic because it smells much like dinner. A paper published earlier this month, meanwhile, found that microplastics can cause aneurysms and reproductive changes in fish.
The new study by scientists at Cardiff University’s Water Research Institute fills in a few more of the blanks. Through existing published data, the researchers examined the gut contents of more than 2,000 mammals, reptiles, fish and invertebrates, ranging from fish just 9 mm (0.35 in) long to 10-meter-long (33-ft) humpback whales.
This enabled them to unearth a relationship between their size and the largest pieces of plastic waste they could consume, which they calculated to be a ratio of around 20:1. The plastic samples studied include all kinds of materials, ranging from hosepipes in a sperm whale to plastic banana bags inside green turtles, but overall the largest pieces an animal could eat was around five percent of its size.
“All of us will have seen distressing, often heart-breaking, images of animals affected by plastic, but a great many more interactions between animals and plastic are never witnessed,” says Project leader Professor Isabelle Durance. “This study gives us a new way of visualizing those many, many unseen events. While we understand increasingly where concentrations of plastic in the world’s aquatic ecosystems are greatest, it’s only through work like this that we can know which animals are likely to be in danger from ingesting it.”
The research was published in the journal Nature Communications.
Source: Cardiff University