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Va study to focus on plastic debris, marine life

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News,Science and Technology

NEWPORT NEWS, Va. (AP) — A seabird snared by plastic six-pack rings, plastic pellets filling up a fish's stomach — such images isn't new.

But what happens when tons of plastic debris slowly break down in the open ocean and leach toxic chemicals, furnish an unnatural reef for microbes or get gobbled up by marine life, from plankton on up the food chain, is far less understood.

We also don't know what plastics — broken into tiny brittle bits or pulverized to powder — wreak on the marine ecosystem when they settle into Chesapeake Bay sediment or mingle with beach sand.

Rob Hale at the Virginia Institute of Marine Science in Gloucester Point hopes to rectify that.

"I'm interested in the stuff that might reside in sediments and up in coastal sediments (or) end up on the shoreline, which gives greater potential exposure to whatever lives there," said Hale, an environmental chemist.

"Local filter feeders would be potentially exposed to these elevated levels of particles and be more vulnerable. Oysters, which filter feed, zooplankton, which support the food chain, could potentially be affected. The interesting thing is, no one's really looked at that."

Hale is seeking funding to do so, perhaps in collaboration with Tracy Mincer at the Woods Hole Oceanographic Institution in Massachusetts. Mincer just launched a three-year research project to study the role of microbes on larger plastic debris caught in the currents and gyres of the open sea. Hale invited Mincer to speak at VIMS recently on that work.

But it's the smaller plastics — half a millimeter or less — and the chemical additives they contain that most interest Hale. Those additives include high levels of flame retardants, bisphenol A and phthalates.

"We're trying to understand what kinds of contaminants can be released from the plastics," Mincer said, "and understand also how these pollutants are affecting the population of higher animals."

Contrary to conventional wisdom, plastic isn't forever. Many plastics grow brittle when exposed to light. They're digested by microbes or get ground up on beaches.

"It lasts for potentially a long time, but not forever," Hale said. "We ignore it long enough, it will eventually break into little pieces. And people say, 'Good, it's gone,' but it's not gone.

"You may pick up a big plastic bag off the beach," he said, "but don't even notice the little stuff intermingling with sand grains. You can go in and clean up everything you see, but most of the plastic may still be there in the form of a powder.

"To me, the sediments and the intertidal and the beach may even be more interesting because perhaps more plastic is concentrated there, and the processes that break plastic into little pieces are accelerated in those environments."

Those little pieces are more easily gobbled up by small sea creatures, which are eaten by bigger creatures, which end up ingesting not only the plastics but the chemical additives they contain. Many of those creatures also end up on a dinner plate.

Mincer is a marine biochemist whose work is being funded by the National Science Foundation in conjunction with the Sea Education Association. His primary focus is on microbes multiplying on plastic debris in open water, but his findings would also apply to estuaries like the Chesapeake Bay.

"The critters — worms and crabs — they're interacting with it, possibly eating it," said Mincer. "You've got a thousand times more abundant microbes per gram or per millimeter than you do in the water column. These things are multiplying in high numbers. We're not sure of the impact that they're making at the microbial level, and it all adds up. We don't know what kind of impact they're making on the higher system."

About 245 million tons of plastic are produced every year, rivaling the biomass of all 7 billion men, women and children on the planet, according to Mincer.

It's been forbidden by international treaty since 1988 to dump plastics in the open ocean, yet plastic debris still manages to migrate there.

Much of it comes from storm water runoff, sewer overflows, plastic trash discarded in a "haphazard way," said Hale, to get washed downriver to the coast.

Some of it gets pitched by accident from cargo ships. "It happens quite often," said Mincer.

Plastic debris that casts off from Virginia or some other Atlantic state and makes it to the open sea will likely get carried off by the currents and within six weeks end up in the North Atlantic Subtropical Gyre, Mincer said.

This gyre, or giant whirlpool, is one of five around the world created by the spin of the earth and thermal forces in the atmosphere to form the biggest biomes, or habitats, on our planet, Mincer said.

These are also delicate habitats being inundated with plastic debris; a huge debris field dubbed the Pacific Garbage Patch stretches five times the size of Texas.

Plastics provide a substrate, or a home, for microbes to anchor on and multiply; plastics last far longer than most natural floating substrates, said Mincer. They can also transport harmful algal species, pathogens and pollutants.

The risk isn't limited to marine species living in and around the gyres.

"Anything that has part of its life cycle out in the open ocean would be affected," said Mincer. In his own area, for instance, a native river eel travels to the Sargasso Sea to spawn, then returns.

"They can be easily threatened," Mincer said, "through a virus and other stuff that can be transported (by microbes)."

Thousands of wildlife species are sustained by the Chesapeake Bay; many of them are migratory species.

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Information from: Daily Press, http://www.dailypress.com

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