Trash Free Seas

Tsunami Debris 101

While oceanographers are monitoring the Japanese tsunami debris, there are many questions and misconceptions about it that need to be addressed.

Ocean debris from the Japanese Tsunami - Debris from the Japanese Tsunami spotted in the Pacific Ocean. Photo: NOAA

The earthquake and subsequent tsunami that occurred last March in Japan swept approximately 5 million tons of debris into the Pacific Ocean, according to the Japanese Ministry of the Environment. While uncertainty remains on how much of this debris will reach the United States, the potential impact on our ocean's health from tsunami debris is huge.

While oceanographers are monitoring the tsunami debris, there are many questions and misconceptions about it that need to be addressed.

Where's the floating island of trash?

The fact is, there is no floating island of trash. Despite common misconceptions, marine debris fields are not usually dense patches that can be easily spotted and tracked from plans and other monitoring equipment. Rather, they are dispersed over large areas of the ocean -- debris can be miles apart and even at wide-ranging depths.

NOAA and NASA have been tracking this debris field since shortly after the tsunami hit. However, five weeks after the disaster, the debris was so dispersed that it could no longer be tracked by satellite.

In addition, the variety of debris—which includes objects like homes, fishing vessels and small freighters—makes it impossible to know how much debris is still afloat, has sunk or has degraded.

Tsunami debris is a danger to wildlife

The tsunami debris could have significant impacts on wildlife throughout the Pacific.

Debris washing ashore around the Northwest Hawaiian Islands could damage reefs, introduce invasive species and impact the Laysan and black-footed albatross, Hawaiian monk seal, green sea turtle, and other threatened and endangered species.

Derelict fishing gear could threaten seabirds and migratory Pacific species like bluefin tuna, green and leatherback sea turtles, mako and blue sharks, and whales that use North Pacific waters to forage, breed and migrate.

Projecting landfall

While predicting landfall for marine debris is difficult, researchers are working on projections for where and when the tsunami debris could wash ashore.

Drs. Nikolai Maximenko and Jan Hafner of the University of Hawaii International Pacific Research Center are using computer models and at-sea reporting from ships to project the trajectory of the tsunami debris field.

Their most recent models, which account for various magnitudes of wind, show that while some debris will wash onto Hawaiian beaches, much will slip between the islands and settle in the North Pacific Gyre. Once the debris oscillates around the Gyre—approximately 5 years from now—it is safe to assume Hawaii will be the main coastline impacted by the debris.

California may be protected to some degree by coastal upwelling, but Drs. Maximenko and Hafner believe some significant amounts will wash onto the coasts of Washington, British Columbia and Alaska. It is possible that some debris may reach beaches as far south as Mexico.

It should be noted that predictions about when more debris will wash ashore are based solely on models. One oceanographer, Curtis Ebbesmeyer from the University of Washington, predicts a faster trajectory for surface-drifting debris—plastic, fiberglass boat hulls, etc.—as debris moves faster when exposed to wind. For instance, it's wind and not currents that usually drives oil on the surface of the water during an oil spill. Models generated by the Japan Ministry of Environment predict a similar model, with predictions of floating debris passing the Hawaiian Islands to the north and reaching the west coast of the United States in October 2012.

What can I do?

While this is the latest high-profile case of ocean debris, it is just a small part of the overall ocean trash problem. A tsunami's worth of ocean trash is created every year simply by the things we buy, use and throw away. But there are some simple things you can do to help keep trash out of the ocean:

  1. Reduce your use of one-time use items like disposable cups, bottles and straws.
  2. Pick up litter and properly dispose of your own trash. No matter how far away the ocean may seem, trash can find a way to the sea.
  3. Participate or organize a beach, waterway or area cleanup to support trash free seas.
  4. Support legislation to address the marine debris problem.

Get more tips at Keep the Coast Clear.

Is the tsunami debris radioactive?

Because tsunami-generated debris washed out to sea before radioactive water was released at the Fukushima nuclear power plant, it is improbable that tsunami-related marine debris is contaminated. This hypothesis was confirmed in early October when the Russian ship STS Pallada found a 20-foot Japanese fishing vessel northwest of Midway Atoll using coordinates informed by Maximenko and Hafner’s model. The boat was tested for radioactivity, and the results came back normal.

Moving forward, macroalgae and crustaceans will be useful for monitoring the presence of radioactive contaminants that would otherwise be difficult to detect.

Invasive species

The Japanese tsunami was a rare natural disaster that was coupled with extensive modern infrastructure and a large amount of already biofouled material launched into sea, becoming an unprecedented event. The dock that washed up on Agate Beach, Ore., on June 3, 2012, was a major wake-up call to the threat of invasive species. Before this, invasive species had not been identified as a major tsunami issue since scientists thought that coastal species would not survive a long time in the oceanic environment.

The arrival of the dock containing many coastal species dispelled this assumption. Scientists were amazed by how many species survived on the dock and that some species were not native to Japan, but they recognize that they do not know how many species were originally on the dock.

Tsunami debris that was originally submerged in the marine environment (e.g. docks, harbor infrastructure, boats, etc.) pose a higher risk of containing coastal aquatic invasive species and therefore a greater threat to the West Coast’s coastal waters than tsunami debris of terrestrial origins (e.g. house, soccer ball, fridge, etc.).

Terrestrial origin debris is not seen as a high risk for coastal invasive species since this material picks up pelagic species as it floats in the oceanic environment and often pelagic species will not survive in coastal environments. The focus of tsunami debris having high invasive species risk should therefore be placed on debris that originated in the marine environment.

Recovery efforts in Japan

For more information about the ongoing recovery efforts in Japan, please watch our video from Nick Mallos' time in the impacted region.

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