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For hungry young sea turtles, plastic at ocean's surface is 'evolutionary trap'

By Kyle Barnett
For hungry young sea turtles, plastic at ocean's surface is 'evolutionary trap'
Juvenile sea turtles are particularly at risk of eating plastic waste due to the amount in the world's oceans and spending their early lives feeding near the surface -- where plastic gathers. File Photo by Bill Greenblatt/UPI | License Photo

Aug. 2 (UPI) -- After hatching, young sea turtles spend their early years traveling currents in open ocean and feeding near the surface -- where new research shows they inadvertently eat plastic waste.

Researchers from the University of Exeter reported Monday in the journal Frontiers in Marine Science that they found plastic inside small, young sea turtles on the Pacific and Indian ocean coasts of Australia.

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"Juvenile turtles have evolved to develop in the open ocean, where predators are relatively scarce. Our results suggest that this evolved behavior now leads them into a 'trap,' bringing them into highly polluted areas such as the Great Pacific Garbage Patch," study lead author Emily Duncan said in a press release.

"Juvenile sea turtles generally have no specialized diet -- they eat anything, and our study suggests this includes plastic," said Duncan, a postdoctoral researcher at Exeter's Center for Ecology and Conservation in Cornwall, England.

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For the study, researchers examined 121 juvenile sea turtles -- from hatchlings to a shell measurement of about 20 inches -- that washed up or were caught by accident by fishers on the east and west coasts of Australia.

Five of the seven known species of sea turtle were represented in the study -- green, loggerhead, hawksbill, olive ridley and flatback -- the researchers said.

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Overall, more turtles caught on the east, or Pacific, coast of Australia had eaten plastic -- 86% of loggerheads, 83% of greens, 80% of flatbacks and 29% of olive ridleys.

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On the west, or Indian, coast of Australia, researchers found 28% of flatbacks, 21% of loggerheads and 9% of green turtles had eaten plastic.

None of the hawksbills caught on either coast had eaten plastic, though researchers said they didn't catch many of them.

"We frame the high occurrence of ingested plastic present in this marine turtle life stage as a potential evolutionary trap as they undertake their development in what are now some of the most polluted areas of the global oceans," researchers wrote in the study.

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Some portion of the higher amount of plastic found in turtles on the Pacific coast, the researchers said, could be linked to the Great Pacific Garbage Patch.

The Patch, consisting of 160 million pounds of mainly plastic waste, covers about 600,000 square miles. In 2018, scientists estimated the patch has 1.8 trillion pieces of trash floating in it.

Marine turtles have notably been more prone to plastic pollution than other animals. A study released earlier this year found they were more likely to mistake dirty, smelly plastic for food.

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Another study found plastics in the ocean may look like sea grass to turtles.

The flotilla of trash has been growing in recent years. Earlier this year, scientists created a water flow model to predict how likely it is something blown into the ocean ends up in one of the world's garbage patches.

"These polymers are so widely used in plastic products that it's impossible to pin down the likely sources of the fragments we found," Duncan said.

"The next stage of our research is to find out if and how plastic ingestion affects the health and survival of these turtles," Duncan said.

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