In 2019, French swimmer
Benoit Lecomte swam more than 300
nautical miles through the Great Pacific Garbage Patch to raise awareness about
marine plastic pollution.
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As he swam, he
was often surprised to find that he was not alone.
“Every time I
saw plastic debris floating, there was life all around it,” Lecomte said.
The patch was
less a garbage island than a garbage soup of plastic bottles, fishing nets,
tires and toothbrushes. And floating at its surface were blue dragon
nudibranchs, Portuguese man-o-wars and other small surface-dwelling animals,
which are collectively known as neuston.
Scientists
aboard the ship supporting Lecomte’s swim systematically sampled the patch’s
surface waters. The team found that there were much higher concentrations of
neuston within the patch than outside it. In some parts of the patch, there
were nearly as many neuston as pieces of plastic.
A photo provided by Denis Rieck shows the blue button Porpita species, viewed from above.
“I had this
hypothesis that gyres concentrate life and plastic in similar ways, but it was
still really surprising to see just how much we found out there,” said Rebecca
Helm, an assistant professor at the University of North Carolina and co-author
of the study. “The density was really staggering. To see them in that
concentration was like, wow.”
The findings
were posted last month on bioRxiv and have not yet been subjected to peer
review. But if they hold up, Helm and other scientists say, it may complicate
efforts by conservationists to remove the immense and ever-growing amount of
plastic in the patch.
The world’s
oceans contain five gyres, large systems of circular currents powered by global
wind patterns and forces created by
Earth’s rotation. They act like enormous
whirlpools, so anything floating within one will eventually be pulled into its
center. For nearly a century, floating plastic waste has been pouring into the
gyres, creating an assortment of garbage patches. The largest, the Great
Pacific Patch, is halfway between Hawaii and California and contains at least
79,000 tons of plastic, according to the Ocean Cleanup Foundation. All that
trash turns out to be a great foothold for living things.
Helm and her
colleagues pulled many individual creatures out of the sea with their nets:
by-the-wind sailors, free-floating hydrozoans that travel on ocean breezes;
blue buttons, quarter-sized cousins of the jellyfish; and violet sea-snails,
which build “rafts” to stay afloat by trapping air bubbles in a soaplike mucus
they secrete from a gland in their foot. They also found potential evidence
that these creatures may be reproducing within the patch.
A photo provided by Denis Rieck shows the snail Recluzia species, viewed from the side oral end.
“I wasn’t surprised,”
said Andre Boustany, a researcher with the Monterey Bay Aquarium in California.
“We know this place is an aggregation area for drifting plastics, so why would
it not be an aggregation area for these drifting animals as well?”
Little is known
about neuston, especially those found far from land in the heart of ocean
gyres.
“They are very
difficult to study because they occur in the open ocean and you cannot collect
them unless you go on marine expeditions, which cost a lot of money,” said
Lanna Cheng, a research scientist at the University of California, San Diego.
Because so
little is known about the life history and ecology of these creatures, this
study, though severely limited in size and scope, offers valuable insights to
scientists.
But Helm said
there is another implication of the study: Organizations working to remove
plastic waste from the patch may also need to consider what the study means for
their efforts.
There are
several nonprofit organizations working to remove floating plastic from the
Great Pacific Patch. The largest, the
Ocean Cleanup Foundation in the
Netherlands, developed a net specifically to collect and concentrate marine
debris as it is pulled across the sea’s surface by winds and currents. Once the
net is full, a ship takes its contents to land for proper disposal.
A photo provided by Denis Rieck shows a buoy barnacle, Dosima fascicularis, viewed from the side, with aboral white float at the water’s surface.
Helm and other
scientists warn that such nets threaten sea life, including neuston. Although
adjustments to the net’s design have been made to reduce bycatch, Helm believes
any large-scale removal of plastic from the patch could pose a threat to its
neuston inhabitants.
“When it comes
to figuring out what to do about the plastic that’s already in the ocean, I
think we need to be really careful,” she said. The results of her study “really
emphasize the need to study the open ocean before we try to manipulate it,
modify it, clean it up or extract minerals from it.”
Laurent
Lebreton, an oceanographer with the Ocean Cleanup Foundation, disagreed with
Helm.
“It’s too early
to reach any conclusions on how we should react to that study,” he said. “You
have to take into account the effects of plastic pollution on other species. We
are collecting several tons of plastic every week with our system — plastic
that is affecting the environment.”
Plastic in the
ocean poses a threat to marine life, killing more than 1 million seabirds every
year, as well as more than 100,000 marine mammals, according to
UNESCO.
Everything from fish to whales can become entangled, and animals often mistake
it for food and end up starving to death with stomachs full of plastic.
Ocean plastics
that do not end up asphyxiating an albatross or entangling an elephant seal
eventually break down into microplastics, which penetrate every branch of the
food web and are nearly impossible to remove from the environment.
One thing
everyone agrees on is that we need to stop the flow of plastic into the ocean.
“We need to turn
off the tap,” Lecomte said.
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