Sea Turtles Mistake Plastic for Food: Study
Wed, April 21, 2021

Sea Turtles Mistake Plastic for Food: Study


Oceans are turning into dumpsites due to the plastics being thrown at them every day. Previous reports have shown that approximately 14 billion pounds of tires, cardboard, plastic cups and bottles, and other trash are dumped into the ocean annually. While some of these sink or float, many are eaten by marine animals. What makes plastic useful for people, like its durability and being lightweight, are the same things that increase the threat to marine animals. 

National Wildlife Federation, the United States' largest private, nonprofit conservation education and advocacy organization, reported that of all ocean debris, 65% of plastics came from the shoreline and recreational activities; 25% from smoking-related activities; 8% from ocean and waterway activities, and 1% from dumping activities and medical/personal hygiene. While humans save themselves from this debris, it only puts the world’s oceans and the organisms living in it at risk. It’s estimated that 800 species worldwide are affected by marine debris -- as much as 80% of that litter is plastic. 

“The really sad thing about this is that they’re eating plastic thinking it’s food. Imagine you ate lunch and then just felt weak and lethargic and hungry all day. That would be very confusing,”  Matthew Savoca, a marine biologist from the National Oceanic and Atmospheric Administration, said. 

Due to the increasing amount of plastics dumped into our oceans, marine animals can become entangled in or ingest plastic debris, causing suffocation, starvation, and drowning. Even humans are not immune to this threat because some plastics could break down much quicker into tiny particles, which in turn end up in the seafood we eat. But, among all marine life, sea turtles have become some of the most affected by this pollution. 



How Sea Turtles Are Affected by Plastics

Multiple studies show the devastating impact of plastic on sea turtles. Research suggests that 52% of the world’s turtles have eaten plastic waste. Some subspecies of sea turtles such as the plant-eating green turtle and carnivorous loggerhead were shown to be consuming plastic in alarming quantities. Loggerheads, as reports have shown, ate plastic 17% of the time they encountered it, likely mistaking it for jellyfish. The rate is higher for green turtles with 62%. 

A 2018 study suggests that ingesting even a single piece of plastic can be deadly for sea turtles and younger turtles are at a higher risk of dying from exposure to plastic than adults. "Because of their digestive tract, they don't regurgitate anything. If it ends up in the wrong place, even one little thin, filmy piece of plastic can block that canal and mean that nothing can pass and ultimately the blockage can result in death,” lead author Dr. Britta Denise Hardesty from Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) said.

According to the BBC, an operational business division of the British Broadcasting Corporation responsible for the gathering and broadcasting of news and current affairs, findings only show that the surge of plastic into the world's oceans is taking an increasing toll on iconic marine species. The researchers also discovered that younger turtles were taking in far more plastic than adults. It was reported that 54% of post-hatchling turtles and 23% of juveniles have ingested plastic compared to 16% of adults. "We think that small turtles are less selective in what they eat than large adults who eat seagrass and crustaceans, the young turtles are out in the oceanic area offshore and the older animals are feeding in closer to shore,” Dr. Hardesty said.

Another 2018 study published in the journal Global Change Biology reported that more than 800 synthetic particles were found in the turtles living across the Atlantic, Pacific, and Mediterranean. The researchers examined more than 100 sea turtles of all seven species and conducted necropsies or animal autopsies on turtles that had died either by stranding or by being accidentally caught by fishermen. According to CNN, an American news-based pay television channel owned by AT&T's WarnerMedia, they found synthetic particles that were made up of tires, cigarettes, clothing and marine equipment, including ropes and fishing nets.

"The ubiquity of the presence of the particles and fibers underlines the gravity of the situation in the oceans and our need to proceed with firm and decisive action on the misuse of plastics," senior study author Brendan Godley, professor of conservation science at the University of Exeter, said.

Unfortunately, ingesting plastics is not the only problem sea turtles are facing. Entanglement in abandoned fishing nets can easily kill them through drowning or preventing individuals from escaping predators or hunting. 



Why Sea Turtles Are Ingesting Plastics

Experts have already explained that the reasons why the world’s turtles are eating plastic waste are simple: a floating plastic bag can look like a lot of jellyfish, algae, or other species, encouraging them to eat these. However, a recent study investigated it deeper and discovered that the animals are mistaking plastics for food due to their smell. 

The study conducted by scientists from the University of North Carolina at Chapel Hill examined 15 loggerhead turtles that were in captivity for five months. They delivered a series of airborne smells through a pipe, including clean plastic, ionized water, their usual food and plastics coated with microbes, algae, plants, and animals, as they are in the ocean. They aimed to know how the turtles acted with their nares out of the water as well as how many breaths they took to determine their attraction to the different smells.

The results shocked the researchers. According to EcoWatch, a leading environmental news site engaging millions of concerned individuals every month, the turtles showed an "indistinguishable" interest in their food and the ocean-like plastic. They responded to the smell of food and ocean-soaked plastics while ignoring the scents of clean plastic and water. This reveals the deeper implications of the increasing amounts of plastic in our oceans. 

"We were surprised that turtles responded to odors from biofouled plastic with the same intensity as their food. We expected them to respond to both to a greater extent than the control treatments, but the turtles know the smell of their food since they've been smelling and eating it in captivity for 5 months. I expected their responses to food to be stronger,” Joseph Pfaller of the University of Florida, Gainesville said.