The unexpected consequences of natural disasters…

West Coast beachcombers have treasured the rare sightings of Japanese glass floats; spherical buoys strung together to aid fishermen in managing their catch. It was once thought that these translucent orbs took nearly a decade to reach the U.S.–traveling up to 8,000 miles of open sea.


Japanese glass floats were among the debris from the 2011 Japanese tsunami that found its way to North America, and along with it, a few unanticipated surprises.

But in 2011, 5 million tons of debris was washed out to sea after the devastating tsunami hit Japan, and reached the Pacific coast of North America only one year later. This massive debris field carried a variety of glass floats, as well as docks, ships, buoys, and parts of buildings. But even more surprising was the fact that along with this debris came hundreds of living plants and animals, like wayward castaways, according to James Carlton, a world-renowned expert on aquatic invasive species.

“There are no records in historical literature, scientific literature or management policy literature of anything rafting in from Japan or China or Russia and landing, alive, on the Pacific coast of North America,” said Carlton during his presentation on February 11 at the Coastal State Discussion Series sponsored by Rhode Island Sea Grant. “Ocean-scale rafting events appear to be so rare that we would not expect to see them within a human lifetime.”

Nearly 400 invasive species, from mussels and crabs to fish and seaweed, have been found on tsunami debris that has landed everywhere from Alaska to California and Hawaii. 

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Carlton explained the reasons to be alarmed by this sudden proliferation of invasives.  “Our concerns about invasive species go to a variety of levels … Is there an economic issue? Will it change your life?” he said, explaining that diseases, such as cholera, and pesky organisms like the zebra mussel have spread around the world, primarily through ballast water. Carlton added that while there are public health and economic issues associated with invasive species, the deeper environmental issues include the long-term ramifications in the food web, and the ability of the environment to adapt. “The world is biologically expanding.”

Carlton and other researchers are still collecting and counting as debris continues to arrive, even years later.

“We are now in year five, and the picture is a very wide dispersal field of debris,” he said, explaining that the variety of open-ocean current patterns jettisoned material in westerly directions at a variety of speeds, both north and south of Japan.

Such a wide dispersal has allowed for the successful open-ocean rafting of species – either by hitchhiking on tree trunks or drifting docks – that were once thought to only survive within the shallow waters of the Japanese coast. This has given marine biologists like Carlton the opportunity to observe the dispersal of species on a scale that would normally take a lifetime to witness.

“The concept here is that we’ve changed the boats,” said Carlton, explaining that many of the boats constructed today are mostly made with plastic and fiberglass materials, which are non-biodegradable. This material makes up the majority of ocean debris and provides a much longer-lasting platform for all varieties of life to thrive. “If the thing you are floating on does not dissolve from under you within a short period of time, it becomes a test of how long you can survive on the open ocean.”

“It’s a symptom of modern times,” said Sam Chan, extension specialist at Oregon Sea Grant, in an article published last August. Chan, who has been working with Carlton on this project, explained that as coastal development continues to increase more debris like this can be expected in the future.

Carlton said that while there may be tons of debris washing ashore, getting to it is not always easy. Sometimes debris washes ashore in very remote places that are difficult to access, and sometimes local officials move quickly to remove the debris before scientists have had a chance to investigate. In Newport, Oregon, officials hacked, burned, and buried the flora and fauna that had arrived along a 66-foot harbor dock from the port of Misawa to prevent the spread of invasive species. In remote areas such as Olympia National Park in Washington State, federal authorities and the U.S. Coast Guard completed similar actions in hopes of eradicating the potential for alien growth.

Species found on one of three docks from the Port of Misawa.

Species found on one of three docks from the Port of Misawa.

“The biology of the debris is one thing we haven’t been studying,” said Carlton, noting ongoing efforts by citizens, conservation groups, beach rangers, and private institutions in wide-scale mapping and collection of debris across to help document what’s being found. “What’s on the debris could tell us a lot more about its history, its origin, and its potential to move species, which is one of the invasive species issues.”

Carlton and other researchers have worked together to establish protocols and procedures for the wide-scale mapping and collection of debris across the Pacific. “Everyone you can imagine, from citizens and beach rangers to conservation groups and private institutions, contributed to the process of collection,” he said. Other groups have been established and continue to operate with similar on-going objectives to collect and sample species that survived the year-long voyage.

While the full impact of the tsunami debris and the organisms clinging to it is still being studied, Carlton says the episode draws attention to how coastal development and natural disasters may increase the rate at which invasive species travel, speeding up the biological expansion of the world, for better or worse.  “If we can prevent future invasions by understanding their vectors (debris, ballast water, etc.), we won’t have to worry about future alterations for which we might not have any control.”

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