A few bits of plastic are deadly for sea life

Ocean plastic kills sea creatures. It can obstruct, perforate or twist their airways and gastrointestinal tracts.

- BY SUSANNE RUST

SAND art in Whitby, England, depicts plastic inside a humpback whale and a calf.

Now new research shows it takes just six pieces of ingested rubber the size of a pencil eraser to kill most seabirds.

For marine mammals, 29 pieces of any kind of plastic — hard, soft, rubber or fishing equipment — are often lethal.

It’s the first time researchers have quantified how much and what kind of plastic — soft, hard, rubber or fishing debris — is needed to kill a bird, marine mammal or a turtle.

"Seeing the particularly small thresholds for rubber and seabirds, for example, that just six pieces of rubber, each smaller on average than the size of a pea was enough to kill 90% of seabirds that ingested it. ... That was particularly surprising to me," said Erin Murphy, a researcher with the group Ocean Conservancy and the department of ecology and evolution at the University of Toronto.

The seabirds were less sensitive to hard plastic: It would take 25 pieces of the pea-sized hard plastic pieces to ensure a 90% chance of dying.