[Coral-List] Surprise

Vassil Zlatarski vzlatarski at gmail.com
Mon Nov 6 20:12:25 EST 2017

 <https://www.smithsonianmag.com/smart-news/> Dear Coral-Listers,Yesterday
with same subject was posted very long link.  Sorry for the inconvenience,
down is the text without  the picture.Cheers,

Corals Seem to Like the “Taste” of Plastic Corals are attracted to the
material not for its coloring, but for one of its many chemicalsA coral
polyp chowing down on a flake of white plastic (Alex Seymour, Duke
University )
By Jason Daley <https://www.smithsonianmag.com/author/jason-daley/>
November 3, 2017

One of the problems with plastic in the oceans is that when it breaks down
into tiny bits of microplastic, it looks like fish food. Then, marine
creatures swallow it, thinking it is prey. But as Ben Guarino at *The
Washington Post*
reports, researchers have discovered that, at least when it comes to coral,
the animals may eat plastic for another reason: They think it tastes

Researchers at Duke University hand fed corals in a saltwater tank
collected off the Carolina coast, feeding them tiny grains of sand and
plastic. During the study, when the bits of sand came near a coral polyp’s
mouth, it would close the orifice and use the cilia on its body to brush
the sand way. When a bit of plastic floated by, however, they brought it to
their mouth using their tentacles. While the coral ate 80 percent of the
six varieties of plastic grains dropped on them, they only ate sand 1 in 10

The researchers performed a second experiment, offering the coral bits of
plastic covered with a biofilm. It turned out, the corals preferred the raw
plastic to the bio-contaminated bits, suggesting that there’s something in
the plain plastic bits they find appealing. The study appears in the
journal *Marine Pollution Bulletin

“Corals in our experiments ate all types of plastics but preferred unfouled
microplastics by a threefold difference over microplastics covered in
bacteria,” study co-leader Austin S. Allen, a Duke Ph.D. candidate says in
a press release <http://phys.org/news/2017-10-corals-plastics.html>. “This
suggests the plastic itself contains something that makes it tasty.”

The researchers aren’t sure yet what that substance is. “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,” Duke GIS analyst and study co-lead
Alexander C. Seymour adds.

This is just one more wrinkle in the complicated relationship between ocean
life and plastics. As Veronique Greenwood at *The New York Times*
reports, over 200 species of sea life—including turtles (who mistake bags
as jellyfish), birds, and now corals—have been recorded eating plastic.
Researchers are just beginning to understand how plastic consumption is
impacting creatures. These plastics can enter into the food chain—possibly
even working their way up to humans. And there is still many unknowns about
what those plastic compounds do to different animals. One recent study
suggests that nanoparticles of plastic can make it into the brains of fish
<https://www.sciencedaily.com/releases/2017/09/170925104730.htm>, causing
behavioral changes.

Plastic in the ocean is a massive problem. A study from 2015
estimated there are between 15 and 51 trillion bits of plastic in the
oceans, creating a plastic soup. There’s so much plastic it’s even making
it to pristine areas of the Arctic
once believed to be free from pollution.

While the coral might find the plastic bits tasty, their guts do not.
Within 24 hours, most of the corals had expelled the indigestible plastic
grains, but 8 percent got stuck in their intestines, which could lead to
fatal blockages and the leaching of chemicals from the plastic, which could
have hormonal effects.

As Guarino reports, it’s possible that the situation at sea may be
different—coral in the wild may avoid tiny plastic pieces. The lab is
currently working to find out if other marine invertebrates also find the
plastic bits appealing, according to Greenwood. If it turns out that coral
and other creatures are being impacted in the wild because of plastic’s
tasty chemicals, it could lead to calls to change the way the stuff is
made. “If we could manufacture plastic to taste attractive, maybe we can
manufacture plastic to taste repulsive,” Seymour tells Greenwood. “Maybe we
can prevent critters from eating plastic in the first place.”

The best solution, of course, is keeping plastic out of the ocean. But
that’s easier said than done: 9 million tons of plastic
enter the ocean each year. And human trash has made it all the way to the
bottom of Earth’s
spots in the Mariana Trench.

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