California Coast & Ocean

Far out in the Pacific Ocean, about halfway between California and Hawaii, air and ocean move together in a huge clockwise spiral known as the North Pacific subtropical gyre. A phenomenon caused by the heating and subsequent cooling of air as it moves from the equator toward the polar regions, the gyre (one of five major subtropical gyres in the world) has been avoided by sailors for centuries because there is very little wind within it. It contains one of the regions known as "horse latitudes," reputedly named by Spanish sailors who were frequently becalmed there and forced to throw their livestock overboard. Gyres are also known for having few fish, particularly top predators, because of their low levels of nutrients--they are sometimes referred to as "ocean deserts."

One thing the North Pacific subtropical gyre has plenty of, though, is plastic. Plastic debris swirls with the current for miles and miles, brought here from around the Pacific Rim. In 1999, researchers from the Long Beach--based Algalita Marine Research Foundation discovered six pounds of plastic for every pound of zooplankton floating in the surface waters of the gyre. This included not only such ubiquitous debris as plastic bottles and bags, but also hundreds of tiny plastic fragments floating in what Algalita founder Charles Moore describes as a "plastic-plankton soup." Plastics don't biodegrade, but in the ocean they do break down from exposure to sunlight and wave action into "microplastic debris"--what one scientist describes as "plastic powder."

Many people understand the damage that larger pieces of plastic trash can do to ocean life, having seen countless pictures of turtles trapped in abandoned fishing nets, fish maimed by six-pack rings, and birds asphyxiated by plastic bags. But in the long run, it may be small bits of plastic that do the most harm. Seabirds often mistake smaller plastic bits for food and eat them, or feed them to their chicks. The plastic takes up space in the chicks' stomachs and can cause them to starve to death. A 1994--95 study of 251 dead or injured albatross chicks on Midway Atoll, near the northwestern end of the Hawaiian archipelago, found only six that did not contain plastic.

Microplastic debris is small enough to be ingested by a wide variety of marine life, including barnacles, lugworms, and zooplankton, a key link in the food chain. Japanese researchers recently found that these tiny fragments floating through the ocean act as sponges for toxic chemicals that are not water-soluble, such as PCBs, DDE, and PAHs--known or suspected carcinogens and endocrine disruptors (substances that may have adverse affects on the developmental and reproductive systems). Very little research has been done on what effects, if any, microplastic debris has on marine organisms, but its potential for introducing endocrine disruptors and other toxins into the food chain--which ultimately includes humans--is disturbing.