July 17, 2013 — Many whales, albatrosses, and turtles have been found with plastic junk in their stomachs, while others have become entangled in packaging. These large animals have come to symbolize the growing problem of oceanic pollution. But a number of new studies suggest that floating plastics are also providing a new habitat—the “plastisphere”—for smaller marine residents, from insects to microbes.
Plastics have become the most common type of debris in the seas. Contrary to popular depictions of floating garbage islands, most of this junk consists of tiny fragments no bigger than a fingernail. Although they are small, these pieces can become trapped in large concentrations within circular ocean currents called gyres. Parts of the North Atlantic Gyre, for example, hold more than 50,000 plastic pieces per square kilometre.
“The open ocean is low in nutrients and often likened to a desert. Now, we have these microbial reefs—pieces of confetti-like plastic that are their own ecosystem,” said Linda Amaral-Zettler from the Marine Biological Laboratory in Woods Hole. “We’re concerned about how these pieces are changing the nature of this large body of water.”
Along with Erik Zettler from the Sea Education Association and Tracy Mincer from the Woods Hole Oceanographic Institution, Amaral-Zettler has been trawling the North Atlantic gyre with nets for 25 years, to collect samples of this debris. Focusing on microbes, they found that these fragments harbor a very different community of bacteria than the surrounding water. “There’s evidence for predation, symbiosis… everything you see in a normal ecosystem but shrunk down to this tiny sphere of life,” she said.
Earlier studies have shown that microbe communities can vary considerably between different parts of the ocean, depending on environmental factors like temperature and salinity. Nevertheless, Amaral-Zettler said, “it was still really striking how different the community we found in plastic was.” For example, the genus Vibrio accounted for a quarter of the microbes on the plastics, but less than 1 percent of seawater communities.
Read the full story at The Scientist