Scientists aboard the 'Robert C. Seamans' study colonies of microbes that thrive in the synthetic ocean 'plastisphere' 10 miles off the coast of San Diego. The plastisphere, a marine ecosystem that starts with bacteria on particles of discarded plastic, is drawing increasing attention. Scientists fear it might host pathogens and leach dangerous chemicals. Photo: Bob Chamberlin

By Louis Sahagun
26 December 2013 (Los Angeles Times) – Elizabeth Lopez maneuvered a massive steel claw over the side of a 134-foot sailboat and guided its descent through swaying kelp and schools of fish 10 miles off the coast of San Diego. She was hoping to catch pieces of a mysterious marine ecosystem that scientists are calling the plastisphere. This biological community starts with particles of degraded plastic no bigger than grains of salt. Bacteria take up residence on those tiny pieces of trash. Then single-celled animals feed on the bacteria, and larger predators feed on them. “We’ve created a new man-made ecosystem of plastic debris,” said Lopez, a graduate student at the University of San Diego, during the recent expedition. The plastisphere was six decades in the making. It’s a product of the discarded plastic — flip-flops, margarine tubs, toys, toothbrushes — that gets swept from urban sewer systems and river channels into the sea. When that debris washes into the ocean, it breaks down into bits that are colonized by microscopic organisms, many of them new to science. Researchers suspect that some of the denizens may be pathogens hitching long-distance rides on floating junk. Scientists also fear that creatures in the plastisphere break down chunks of polyethylene and polypropylene so completely that dangerous chemicals are leached into the environment. “This is an issue of great concern,” said Tracy Mincer, a marine geochemist at the Woods Hole Oceanographic Institution in Massachusetts. “Microbes may be greatly accelerating the weathering of plastic debris into finer bits. If so, we aren’t sure how zooplankton and other small creatures are responding to that, or whether harmful additives, pigments, plasticizers, flame retardants and other toxic compounds are leaching into the water.” About 245 million tons of plastic is produced annually around the world, according to industry estimates. That represents 70 pounds of plastic annually for each of the 7.1 billion people on the planet, scientists say. The waste gathers in vast oval-shaped ocean “garbage patches” formed by converging currents and winds. Once trapped in these cyclonic dead zones, plastic particles may persist for centuries. The physiological effects of plastic debris on the fish, birds, turtles and marine mammals that ingest it are well-documented: clogged intestines, restricted movement, suffocation, loss of vital nutrients, starvation. The effects of the plastisphere are only beginning to be understood. Edward Carpenter, a professor of microbial ecology at San Francisco State University, first reported that microbes could attach themselves to plastic particles adrift at sea in 1972. He observed that these particles enabled the growth of algae and probably bacteria and speculated that hazardous chemicals showing up in ocean animals may have leached out of bits of plastic. […] “We’re changing the basic rhythms of life in the world’s oceans, and we need to understand the consequences of that,” said marine biologist Miriam Goldstein, who earned her doctorate at UC San Diego’s Scripps Institution of Oceanography by studying plastic debris in the Great Pacific Garbage Patch between Hawaii and California. [more]

An ecosystem of our own making could pose a threat