Choking plastics and deafening noise in the world’s oceans may be harming wildlife in more ways than scientists previously thought.
In two new studies published Monday, researchers found stinky plastics may be luring sea turtles while ship noise may be damaging crabs’ ability to protect themselves from prey. Both studies, from the University of Florida and University of Exeter in England, were published in the journal Current Biology.
In the UF study, lead author Joe Pfaller said sea turtles responded to smelly plastic picking up ocean odors with the same intensity as they did to their own food.
"This 'olfactory trap' might help explain why sea turtles ingest and become entangled in plastic so frequently,” he said in a statement.
Researchers have previously thought turtles and other wildlife relied mostly on sight, mistaking plastic bags, jugs and other objects as jellyfish or their typical food, the study said. But the research found that smell may play an equally important role for loggerhead sea turtles.
As plastic floats through the ocean, it can pick up algae, plants, small animals and other microbes that mask the plastic and trick turtles.
For the experiment, the researchers tested 15 different loggerhead turtles. Each was exposed, in random order, to water, turtle food, clean plastic and plastic that had floated in the ocean for five weeks. When the turtles encountered food and the fouled plastics, they responded and sniffed them in the same ways.
Pfaller said this may also explain why turtles often become trapped in rafts of plastic that don’t look like food.
Just as plastics have taken their toll on turtles, whales and hundreds of other species, researchers believe noiser oceans are increasingly harming marine life. In 2016, the National Oceanic and Atmospheric Administration adopted a 10-year plan to deal with the noise interfering with dolphins and other marine life’s ability to hunt and reproduce. University of Miami researchers looking at reseach fish during the 2018 Ultra concert on Virginia Key also found the loud music caused the fish to react like they were being chased by predators.
For the recent University of Exeter study, researchers looked at shore crabs that gradually change their shell color to blend in with their surroundings when they hear prey approaching.
Crabs exposed to ship noise lost the ability to camouflage themselves, the study found. After eight weeks of exposure to the noise, they altered their colors only half as much. Those exposed to simulated shore bird attacks also failed to scramble for cover as they normally would, the study found.
The authors say the study suggests researchers should consider looking more closely at how ocean noise affects survival skills, not just how it interferes with communications like sonar or other functions more obviously related to noise.