We’ve seen enough videos and pictures of sea turtles with straws sticking out of their noses or trapped in plastic to know that plastic waste has a detrimental impact on marine life. It has long been believed that sea turtles are especially susceptible to waste because it so closely resembles their natural prey, that being jellyfish.
New research suggests that plastic waste not only resembles their food, but it smells like it as well.
According to Joseph Pfaller of the University of Florida, “We found that loggerhead sea turtles respond to odours from biofouled plastics in the same way they respond to food odorants, suggesting that turtles may be attracted to plastic debris not only by the way it looks but by the way it smells.”
To test this theory, Pfaller and his team of researchers examined the reaction of 15 loggerhead turtles to odours sprayed into their holding tank. Each turtle was exposed to four different odours, turtle food containing fish and shrimp, “biofouled” plastic that mirror’s how it smelled in the ocean, and two controls: clean plastic and deionized water.
All 15 of the turtles were bred in captivity, having only ever eaten one kind of food, leading scientists to believe that the loggerhead turtles would be more attracted to the food they’re used to. This was not the case.
They found that the turtles responded to the smells of biofouled plastic and turtle food in much the same way, strongly suggesting that turtles often mistake plastic in the ocean for a tasty, but fatal treat.
The reason as to why exactly the turtles are attracted to the smell of plastic is still has to be determined. However, researchers believe it could be because something called dimethyl sulfide, a substance with a particular smell that emanates from the algae and microbes that accumulates on marine plastic when they’ve been submerged for a prolonged period of time.
“Plastics that have spent time in the ocean develop smells that turtles are attracted to and this is an evolutionary adaptation for finding food, but it has now become a problem for turtles because they’re attracted to the smells from the plastics,” said Pfaller.
According to Green Peace, upwards of 12 million tonnes of plastic enters the ocean a year, that equates to a rubbish truck emptying its entire load into the ocean every minute.
Featured image: Joseph Pfaller