Why do sea turtles eat ocean plastics? New research points to smell

March 09, 2020

One week is all it takes for a piece of plastic floating in the ocean to begin to smell like turtle food.

New research from the University of North Carolina at Chapel Hill shows that plastics floating in the ocean build a coating of algae and microorganisms that smells edible to turtles. The study, "Odors from marine plastic debris elicit foraging behavior in sea turtles," was published March 9 in the journal Current Biology. The Carolina team worked on the study with lead author Joe Pfaller from the Caretta Research Project in Savannah, Georgia.

"This finding is important because it's the first demonstration that the odor of ocean plastics causes animals to eat them," said Kenneth J. Lohmann, Charles P. Postelle, Jr. Distinguished Professor of Biology at Carolina. "It's common to find loggerhead turtles with their digestive systems fully or partially blocked because they've eaten plastic materials. There also are increasing reports of sea turtles that have become ill and stranded on the beach due to their ingestion of plastic."

The most important thing people can do to help is to prevent plastics from going into the ocean in the first place. Some practical steps include recycling, properly disposing of trash and recyclables after a trip to the beach or after a boat trip, using reusable or paper shopping bags, and buying larger containers of drinks instead of numerous small drink containers held together with plastic rings.

To understand sea turtle behavior around ocean plastics, the research team compared how sea turtles in a lab setting reacted to smelling odors of turtle food, ocean-soaked plastic, clean plastic and water. The turtles ignored the scents of clean plastic and water, but responded to the odors of food and ocean-soaked plastics by showing foraging behavior. This included poking their noses out of the water repeatedly as they tried to smell the food source, and increasing their activity as they searched. The turtles did not ingest plastics during the experiments and were released into the ocean after the study.

"Very young turtles feed at the surface, and plastics that float on the surface of the ocean affect them," said Kayla M. Goforth, a Carolina biology doctoral student who worked on the study. "Older turtles feed further down in the water column, sometimes on the ocean bottom. Regardless of where plastics are distributed in the ocean, turtles are likely to eat them."

The study raises questions about a number of long-term impacts plastics may have on all ocean species, the researchers said.

"In parts of the Pacific Ocean there are huge areas covered with floating plastic debris," Lohmann said. "One concern this study raises is that dense concentrations of plastics may make turtles - or other species - think the area is an abundant source of food. These areas may draw in marine mammals, fish and birds because the area smells like a good foraging ground. Once these plastics are in the ocean, we don't have a good way to remove them or prevent them from smelling like food. The best thing we can do is to keep plastic from getting into the ocean at all."
-end-
The National Science Foundation funded the study, which also had support from the Bald Head Island Conservancy and University of Georgia Marine Extension on Skidway Island.

University of North Carolina at Chapel Hill

Related Sea Turtles Articles from Brightsurf:

Wonders of animal migration: How sea turtles find small, isolated islands
One of Charles Darwin's long-standing questions on how turtles find their way to islands has been answered thanks to a pioneering study by scientists.

Sea turtles' impressive navigation feats rely on surprisingly crude 'map'
Since the time of Charles Darwin, scientists have marvelled at sea turtles' impressive ability to make their way--often over thousands of kilometers--through the open ocean and back to the very places where they themselves hatched years before.

Study evaluates stress level of rehabilitated sea turtles during transport
A new study co-authored by six scientists with the New England Aquarium has found that rehabilitated Kemp's ridley and loggerhead sea turtles experience a substantial stress response when transported to release locations in the southern United States but that the turtles remained physically stable and ready for release.

World's most complete health analysis of nesting sea turtles conducted in Florida
The most comprehensive health assessment for a green turtle rookery in the world to date is providing critical insights into various aspects of physiology, biology, and herpesvirus epidemiology of this nesting population.

Loggerhead sea turtles host diverse community of miniature organisms
An international team led by Florida State University researchers found that more than double the number of organisms than previously observed live on the shells of these oceanic reptiles, raising important questions about loggerhead sea turtle ecology and conservation.

Sea otters, opossums and the surprising ways pathogens move from land to sea
A parasite known only to be hosted in North America by the Virginia opossum is infecting sea otters along the West Coast.

Sea turtles have a deadly attraction to stinky plastic
Sea turtles around the world are threatened by marine plastic debris, mostly through ingestion and entanglement.

Why do sea turtles eat ocean plastics? New research points to smell
The findings are the first demonstration that the smell of ocean plastics causes animals to eat them.

UCF study: Sea level rise impacts to Canaveral sea turtle nests will be substantial
The study examined loggerhead and green sea turtle nests to predict beach habitat loss at four national seashores by the year 2100.

Monogamous female sea turtles? Yes, thanks to sperm storage
Female sea turtles mate multiply to ensure fertilization. A study of nesting loggerhead female sea turtles in southwest Florida used genotyping to uncover how many fathers were represented in their nests.

Read More: Sea Turtles News and Sea Turtles Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.