Ocean Debris: Habitat for Some, Havoc for Environment, Experts Say
for National Geographic News
|April 23, 2007|
Look under a chunk of plastic afloat in the ocean and you're likely to spot a fish or two. But look inside the stomach of a dead albatross or sea turtle and you're likely to find chunks of plastic.
So goes the paradoxical legacy of plastic debris in the ocean.
Carl Safina is a marine conservationist who has traveled the world's oceans and documented the effects of plastic on marine life.
This past fall, on a research cruise in the remote Pacific Ocean off the coast of Central America, he and his colleagues encountered floating trash serving as habitat for small fish and other marine organisms.
"For reasons not clearly understood, almost any floating object attracts fish that are using it either as cover or some way of being oriented or staying in certain drift lines," said Safina, who co-founded the Blue Ocean Institute in Cold Springs Harbor, New York.
The animals, he noted, likely treat the floating debris as driftwood.
"There's a whole bunch of animals who are evolved to use, and in some cases rely on, driftwood," he said.
Floating trash is as common today as driftwood, and fish and barnacles have adapted to it, he noted.
Charles Moore is the founder of the Algalita Marine Research Foundation in Long Beach, California, and an expert on the accumulation of plastic debris in the ocean.
He said the habitat that plastic debris offers some marine organisms is far outweighed by the negative, and growing, consequences of the trash.
Moore explained that, unlike driftwood, plastic doesn't degrade as it slowly drifts around the ocean.
He added that research conducted by David Barnes, a marine scientist with the British Antarctic Survey, has found that floating plastic has more than doubled the spread of invasive species.
"It's becoming more effective than bilge water and ships as a mechanism of bringing exotics to foreign locations," Moore said.
Packed with Plastic
Safina said plastic is also nothing but trouble for a host of marine organisms.
For example, seabirds like the North Pacific albatross are often found dead with innards full of plastic.
"I'm talking about chunks of plastic. I'm talking about being packed with cigarette lighters. I'm talking about toothbrushes," Safina said. "Horrific things that you can't believe are inside of birds."
Safina is unsure why the birds eat the plastic, but he suggests they may be attracted to it for the same reason that they are drawn to pumice stones and driftwood: Fish eggs and fleshy barnacles are often attached to such floating items.
Once the seabirds digest the food on the stones and driftwood, they cough up the debris.
"I think they probably transferred that to plastics," Safina said. "I don't think they are mistakenly thinking that plastic is food, although that's possible."
He once saw an albatross unsuccessfully try to cough up a toothbrush.
Sea turtles, however, do mistake plastic bags for food, most likely jellyfish, Safina added. Sea turtles are often found dead with their intestines clogged by plastic bags. (See photos of sea turtles.)
"It probably looks enough and feels enough like jellyfish that, even though it doesn't taste like much of anything, they just think they should eat it," Safina said.
(Read related story: "Are Plastic Grocery Bags Sacking the Environment?" [September 2, 2003].)
Moore, of the Algalita Marine Research Foundation, estimates that over the past 50 years, more than a hundred million tons of plastic debris have accumulated in the world's oceans.
"It's not just on the surface or the bottom; it's throughout the water column. And it's in all parts of the ocean. There's no part of the ocean in which plastic debris has not permeated," he said.
(Learn more about pollution and other threats to the world's oceans.)
What's more, he added, the problem is getting worse, increasing by a factor of ten every two to three years.
Fortunately, he added, the issue is gaining recognition. For example, San Francisco's Board of Supervisors last month voted to ban large supermarkets from using plastic bags.
"It's all coming to a head," Moore said. "People are just fed up with living in a soup of toxic trash."
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