A clear white creature drifts lazily in the open ocean. A turtle spots the jellyfish and swims toward it with strong, paddle-like flippers, eyes intent on its prey. Except its prey is actually garbage – a plastic bag floating in its aquatic home. Too late, the sea turtle has already gulped down the debris.
This is the harsh reality for 52% of the world’s sea turtles, according to a new international study. The research, led by Dr. Qamar Schuyler from the University of Queensland, was published in Global Change Biology.
"Currently plastics are being produced at an exponentially increasing rate, but globally our waste disposal technology and capacity is not increasing at the same rate," Schuyler told The Washington Post. An estimated 4-12 million tons of plastic are dumped into our oceans annually.
The threat waste poses to sea turtles isn’t just an upset stomach: Eating plastic can kill or wound turtles by blocking their gut, piercing their intestinal wall, or by releasing toxic chemicals into the creature’s tissues. And even if the plastic doesn’t puncture the stomach, the long-lived creatures still risk death by starvation – some turtles simply stop eating because they feel full after swallowing the indigestible plastic.
To probe this issue further, the team used predictive models in combination with autopsies of dead turtles. Sea turtle population maps were overlaid on marine plastic distributions, and then data from turtle necropsies were included. This, in combination with other factors such as species and stranding observations, gave researchers the information they needed to model the turtles' risk of debris ingestion.
They found that olive ridley sea turtles are the most at-risk species. This is likely due to their open-ocean feeding habits (where debris accumulates) and taste for jellyfish. Currently, olive ridley sea turtles are listed as “vulnerable” by the IUCN Red List, and “endangered” off the coast of Mexico.
In terms of global populations, sea turtles are most at-risk in regions off the east coasts of North America and Australia, South Africa, the east Indian Ocean and Southeast Asia.
This research comes weeks after another study found that more than 60% of seabird species have eaten debris. Just last month, a video of scientists extracting a straw from the nostril of an olive ridley sea turtle went viral.
While sea turtles have swum the Earth’s oceans for more than a 100 million years, these ancient reptiles now face unprecedented dangers from hunting, habitat destruction and, of course, pollution.
Schuyler added: “Unless we take substantial action, the problem is bound to increase.”
Image in text: Camilla Z / Shutterstock