Pictures: Surprising Amount of Trash Found on Deep-Sea Floor

Message in a Bottle

Image courtesy MBARI/NOAA  

Captured by a Monterey Bay Aquarium ROV in 2006, this Coke bottle from Asia rested at Davidson Seamount, 60 miles (97 kilometers) off central California and 5,666 feet (1,727 meters) below the ocean surface.

According to the researchers, the largest proportion of the observed deep-sea debris—about a third of the total—consisted of various things made out of plastic. More than half of those were plastic bags, which are known to pose a risk to wildlife because they can smother, choke, or strangle them.

The second most commonly observed objects were made of metal. About two-thirds of those were aluminum, steel, or tin cans. Glass bottles were also commonly found, as were fishing gear, rope, cloth, and even paper.

Published June 6, 2013

Tangled Web

Image courtesy MBARI    

This tangle of rope and fishing gear lies on the seafloor about 3,280 feet (1,000 meters) deep in Monterey Canyon.

The researchers found that instead of being randomly distributed, trash tends to collect on steep, rocky slopes, such as the edges of canyons. They speculate that the debris is dropped when ocean currents are slowed by obstacles, such as outcrops or canyon walls. (Related: "Odd Sea Creatures Found at Volcanoes, Canyons.")

The researchers also noted that trash tended to be more common in the deeper parts of Monterey Canyon, below 6,500 feet (2,000 meters). Schlining said, "I was surprised that we saw so much trash in deeper water."

Schlining added, "I'm sure that there's a lot more debris in the canyon that we're not seeing. A lot of it gets buried by underwater landslides and sediment movement. Some of it may also be carried into deeper water, farther down the canyon."

Published June 6, 2013

Beating the Drum

Image courtesy MBARI    

This 55-gallon drum was recorded at 9,488 feet (2,892 meters) deep in outer Monterey Canyon in 2007.

The researchers concluded that much of the trash they saw originated on land, instead of being tossed from boats, because it was often mixed with bits of wood and other natural debris from land.

"We don't usually think of our daily activities as affecting life two miles deep in the ocean," Schlining said in a statement.

Published June 6, 2013

Shoe Fish

Image courtesy MBARI

A young rockfish explores an old shoe 1,548 feet (472 meters) deep in San Gabriel Canyon, off Southern California, in 2010.

Monterey Bay Aquarium researchers pointed out that old fishing gear seemed to pose the most obvious threat to marine life, since they saw several animals trapped in it. Other effects were more subtle, they reported.

The scientists saw numerous examples of animals making their homes in or on trash. Although that may provide some immediate benefit, it also may result in changes in the ecosystem down the line, the researchers warned.

"To make matters worse, the impacts of deep-sea trash may last for years," the scientists wrote. "Near-freezing water, lack of sunlight, and low oxygen concentrations discourage the growth of bacteria and other organisms that can break down debris. Under these conditions, a plastic bag or soda can might persist for decades."

Published June 6, 2013

Uncertain Future

Image courtesy MBARI

In 2006, an ROV recorded this plastic draped on a deep-sea gorgonian coral, almost 7,000 feet (2,115 meters) below the surface in Astoria Canyon, off the coast of Oregon.

Researchers hope to further study the impacts of trash on ocean life. The scientists are also working with the Monterey Bay National Marine Sanctuary to assess the impact of a shipping container that fell off a ship in 2004. (Related: "Amsterdam's Lean, Green Shipping Container Homes.")

During research, scientists are occasionally able to pick up trash from the deep sea. But currently, cleaning up the ocean on a large scale is prohibitively expensive. The scientists also note that removing some objects could cause more harm than good, if living things have come to rely on them.

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Published June 6, 2013