The Dangers Of ‘Biofouled’ Ocean Plastic
The amount of plastic debris in our oceans is rising. These bags, bottles, produce containers, and the like threaten all manner of marine life. Fishes, along with animals such as turtles, dolphins, and whales eat the plastic or become entangled in it. How they become entangled is obvious, but why do they eat plastic? This study teases out a potential answer to this puzzling phenomenon.
One of the ways marine animals seek out food or prey is by smell. When plastic in the oceans becomes “marine conditioned” or “biofouled,” it gives off similar odors. To test the theory that the scent of biofouled plastic was fooling marine animals into thinking it was food, researchers tested a group of 15 captive-reared turtles for their response to various odors. Each turtle was placed in an arena and exposed to deionized water, turtle food, clean plastic, and biofouled plastic. All turtles were exposed to all the scents in random order, and each trial was video recorded.
When loggerhead turtles smell something of interest, they spend more time with their nares, or nose-beaks, out of the water. This is often the start of foraging behavior. In this experiment, the turtles’ responses to food and biofouled plastic were indistinguishable. Turtles kept their nares out of the water more than three times longer for these two substances than for the deionized water or clean plastic. These results might explain why turtles are attracted to biofouled plastic. Exactly what odors the turtles are responding to remains unknown, but it seems clear that marine-conditioned plastic becomes a dangerous attractant.
Animal advocates are well aware of the dangers of plastic waste in our oceans. Stories about animals washing up dead on beaches with stomachs full of plastic are all too common. This study offers a plausible explanation as to why marine animals seek out plastic. While Faunalytics never endorses the use of captive animals in experiments, this study offers some conclusions that can also serve as further evidence of why ocean plastic is so deadly.