The risk posed by plastic pollution to the world's declining sea turtle populations has been quantified for the first time.
Does plastic pollution impact turtles?
Sea turtles were among the first marine animals recorded to eat plastic debris, a phenomenon that occurs in most regions of the world and in all seven marine turtle species.
With millions of tonnes of plastic debris entering our world's oceans on a yearly basis, it is estimated that approximately 52 per cent of all sea turtles have eaten plastic.
However, previously, it was unclear as to whether the plastic in our oceans was actually killing sea turtles, or whether they were simply eating it without harm.
Quantifying the impacts of plastic on turtles
To determine how deadly plastic is for turtles, we applied combined research approaches to understand the impact of plastic ingestion, not just on individual turtles, but whole populations of other endangered marine species.
Analysis of nearly 1000 turtles found dead and washed up on beaches around Australia showed that the more plastic a turtle consumes the greater the likelihood that it was killed by that plastic.
Our research shows that a turtle had a 22 per cent chance of dying if it eats just one piece of plastic. Some of the turtles we studied had eaten only one piece of plastic, which was enough to kill it. In one case, the gut was punctured, and in another, the soft plastic clogged the gut.
Solutions to protect marine wildlife
Determining the effect of plastic pollution is having on turtle mortality is a huge step forward for understanding the impact of plastic pollution on global sea turtle populations.
Our scientists found that once a turtle had 14 plastic items in its gut, there was a 50 per cent likelihood that it would cause death. However, that's not to say that a turtle won't die if they consume less than 14 pieces of plastic.
This information is vital so we can better understand the impacts of plastic pollution on marine life, be better equipped to address the problem and work towards viable, and scalable solutions.