The sea turtles around the world are threatened by waste plastics marine, mainly by ingestion and tangles. Now, researchers have discovered new evidence to explain why all that plastic is so dangerous for turtles: confuse the smell of plastic with food, as published Monday in the journal 'Current Biology'.
"We discovered that loggerhead turtles respond to the odors of plastics embedded in organic matter in the same way that they respond to food odors, suggesting that turtles they can be attracted to plastic waste not only because of its appearance, but also because of its smell", explains Joseph Pfaller of the University of Florida, Gainesville. In this regard, he adds:" This 'olfactory trap' could help explain why sea turtles ingest and become entangled in plastic so often. "
Bioincrustation refers to the accumulation of microbes, algae, plants and small animals on wet surfaces, which occurs with plastics in the ocean.
For a long time it was thought that sea turtles see plastics and visually confuse them with prey, such as jellyfish. But Pfaller and his colleagues realized that little was known about the sensory mechanisms that could attract sea turtles to plastic.
In addition, the co-author of the study, Matt Savoca, from the Stanford Marine Hopkins Station, he had shown that airborne odorants used by marine predators to locate good places to find food also emanate from conditioned plastic waste or biocontaminates. So, they asked, what could that mean for sea turtles?
To find out, they recruited 15 loggerhead turtles bred in captivity. They added a series of odorants in the air through a pipe in an experimental arena and they recorded their reactions on video. The smells they tested included deionized water and clean plastic as controls along with the turtle's food, which contains fishmeal and shrimp and bio-embedded plastic.
Behavioral studies found that sea turtles responded to plastic the same way they responded to their food. "We were surprised that the turtles responded to the smells of bio-embedded plastic with the same intensity as your food"admits Pfaller.
"We expected them to respond to both more than the control treatments, but the turtles know the smell of their food since they have been smelling and eating it in captivity for 5 months I expected his responses to food to be stronger, "he adds.
He believes that future studies are still needed to better understand what chemicals were emitted by plastics to arouse the interest of turtles and how water-based odorants could come into play. But the new findings show that plastics of all kinds will present problems for sea turtles and other marine animals.
"The problem of plastic in the ocean is more complex than plastic bags that look like jellyfish or straws Wandering trapped in the nose of a turtle, 'warns Pfaller. These are important and problematic pieces for the puzzle, and all plastics represent a danger to the turtles. "