The researchers at Duke University discovered the concerning situation after the corals in their experiments ate all types of plastics, “but preferred unfouled microplastics by a threefold difference over microplastics covered in bacteria.” The researchers looked at microplastics measuring up to five millimeters, or a fifth of an inch.
The team collected coral samples from the waters off the North Carolina coast and performed two experiments. In the first one, the corals were given eight different types of microplastics mixed with clean sand. They ate every plastic type but mainly ignored the sand.
In the second experiment, they gave the corals clean plastic fragments, and plastic covered in microbes. Over the course of 30 minutes, the corals were three times more likely to eat the clean plastic.
“This suggests the plastic itself contains something that makes it tasty,” said study lead Austin Allen.
Ingesting plastic poses a risk of choking or intestinal blockages which could kill off areas of coral reef. The reef systems are habitats to massive populations of larger marine life like fish, which in turn provide humans with food.
Co-author Seymour added: “When plastic comes from the factory, it has hundreds of chemical additives on it. Any one of these chemicals or a combination of them could be acting as a stimulant that makes plastic appealing to corals.”
This phenomenon especially threatens coral reefs like the Great Barrier Reef off the Australian coast in Queensland. Stretching for 1,400 miles, the largest reef system and biggest living structure on the planet has already sustained damage from other environmental threats over the years.
In a report by The Guardian, the Great Barrier Reef is now at the terminal stage of damage due to a phenomenon known as coral bleaching. The corals lose their color and their white skeletons are exposed (corals turning white or “bleached”) as a result of unusually warm ocean temperatures, overfishing and pollution – which includes plastic waste.
“Ultimately, the hope is that if we can manufacture plastic so it unintentionally tastes good to these animals, we might also be able to manufacture it so it intentionally tastes bad,” said Seymour. “That could significantly help reduce the threat these microplastics pose.”
The study was published in the online edition of the journal Marine Pollution Bulletin.
Major distributors of plastic waste
Research revealed that China, Indonesia, the Philippines, Vietnam, and Sri Lanka are the top five worst marine polluters in 2010. The only industrialized western country on the list of plastic polluters is the U.S. at no. 20.
The top 20 list accounted for a total of 26.5 million tons of mismanaged waste:
- China – 8.8 mt/year
- Indonesia – 3.22
- The Philippines – 1.88
- Vietnam – 1.83
- Sri Lanka – 1.59
- Thailand – 1.03
- Egypt – 0.97
- Malaysia – 0.94
- Nigeria – 0.85
- Bangladesh – 0.79
- South Africa – 0.63
- India – 0.6
- Algeria – 0.52
- Turkey – 0.49
- Pakistan – 0.48
- Brazil – 0.47
- Burma – 0.46
- Morocco – 0.31
- North Korea – 0.3
- United States – 0.28
China is responsible for 2.4 million tons of plastic that makes its way into the ocean, nearly 28 percent of the world total, while the U.S. contributes just 77,000 tons, which is less than one percent, according to the study published in the journal Science. (Related: World's oceans now contain 5 trillion pieces of plastic waste created by humans.)
Read more about environmental threats to these ecosystems at Ecology.news.
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