The islands of Japan sprawl along the Pacific Rim and earthquakes are a frequent occurrence for the Japanese people. However, the Tohoku earthquake that hit on March 11, 2011 was of a different magnitude entirely. The magnitude 9.0 earthquake was the most powerful ever recorded in Japan and the fourth most powerful ever measured worldwide.

The quake’s epicenter occurred 70 kilometers off the eastern coast of Honshu Island triggering an enormous tsunami that swept miles inland with waves up to 133 feet (40.5 meters) high. Nearly 16,000 deaths were reported with thousands more missing. Over a million buildings were either completely or partially damaged.

For days the horrific event transfixed the world’s media, especially the dramatic situation that unfolded at the Fukushima Daiichi Nuclear Power Plant. Here the tsunami breached seawalls and flooded back-up power systems. Meltdowns and explosions followed in three reactors, with radioactive leakage. In addition to the major loss of life the World Bank estimates the economic loss at US$360 billion, making Japan’s earthquake the world’s costliest natural disaster in history.

Nearly eight years later the destruction caused by the 2011 earthquake and tsunami has left a social and political legacy across Japan. However, a different legacy has been carried across miles of ocean to the other side of the Pacific.

When the giant tsunami waves retreated, they carried a flood full of debris. Broken homes, shattered ships and docks, wood, fiber-glass and plastic, in fact anything that could float. This floating debris, carried by ocean currents started to appear on the shores of Hawaii and North America in 2012 and continues to today.

 

“mega-rafting”

Now a paper in the journal Science reveals that this raft of flotsam, also carried a load of aquatic species hitchhiking at a scale never seen before.

japan tsunami debris on California coast mega-rafting

“an extraordinary transoceanic biological rafting event with no known historical precedent,” researchers wrote.

The authors call the phenomenon “mega-rafting” and so far, they have documented nearly 300 living species carried from Japan across the Pacific. Entire communities of coastal marine species indigenous to Japan have appeared on California’s shores.

Mollusks such as mussels were the most frequently found of all invertebrate groups. “Worms, hydroids (sea anemone and jellyfish relatives), crustaceans and bryozoans that form branch-like underwater colonies were also seen.” “The sluggish pace of these “floating islands” may also have made it easier for some species to reproduce and for their larvae to attach to the debris.” Reports Science Daily.

 

Increasing Invasive Invasions?

“I didn’t think that most of these coastal organisms could survive at sea for long periods of time,” said Greg Ruiz, a co-author of the study and marine biologist at the Smithsonian Environmental Research Center. “But in many ways they just haven’t had much opportunity in the past. Now, plastic can combine with tsunami and storm events to create “mega-rafting” opportunities on a large scale.”

“This has turned out to be one of the biggest, unplanned, natural experiments in marine biology, perhaps in history,” said John Chapman of Oregon State University.

 

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