A vessel carried by the Japanese tsunami washed ashore in Oregon, coated in gooseneck barnacles that colonized the boat as it floated across the North Pacific. Several Japanese species also survived the voyage, in the crevices inside and underneath the boat. Credit: John Chapman

The 2011 Japanese tsunami set the stage for something unprecedented. For the first time in recorded history, scientists have detected entire communities of coastal species crossing the ocean by floating on makeshift rafts. Nearly 300 species have appeared on the shores of Hawaii and the U.S. West Coast attached to tsunami debris, marine biologists from the Smithsonian Environmental Research Center, Williams College and other institutions reported in the journal Science on Thursday.

The tsunami formed March 11, 2011, triggered by an earthquake of 9.0 moment magnitude that struck Japan the same day. At its tallest point, the tsunami towered 125 feet over Japan's T?hoku coast and swept millions of objects out to sea, from small pieces of plastic to fishing boats and docks. These kinds of objects, scientists said, helped the species attached to them complete the transoceanic journey.

"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 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 that opportunity on a large scale."

Scientists began finding tsunami debris washing up in Hawaii and western North America in 2012, with living organisms still attached. From 2012 to 2017, they continued to find debris, including buoys, crates, vessels and docks. In total, they detected 289 living species on tsunami debris originating from Japan, and they suspect there are far more that escaped their notice. While the arrivals have slowed down, they have not stopped. The team was still finding new species when the study period ended in 2017.

An infographic depicting findings from Carlton et al. Credit: Carla Schaffer / AAAS

Mollusks such as mussels occurred most frequently of all invertebrate groups. Worms, hydroids (sea anemone and jellyfish relatives), crustaceans and bryozoans that form branch-like underwater colonies were not far behind. Nearly two-thirds of the species had never been seen on the U.S. West Coast. None of the species were known—or expected—to survive a transoceanic rafting voyage between continents, largely because the open ocean is considered to be a harsher environment for creatures used to more hospitable waters of the coasts. However, the slower speed of ocean rafts (1 or 2 knots, compared to 20 or more knots for commercial ships) may have allowed species to gradually adjust to their new environments. 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.

The increase in marine plastics and other more durable debris also made survival easier, according to the researchers. Much of the debris the scientists found rafted ashore was made of fiberglass or other plastic materials that do not decompose and could easily survive six or more years at sea. These materials started becoming common in the mid-20th century, and their dominance is only expected to rise.

Asian amur sea star (Asterias amurensis) found on the Oregon Coast by Oregon State University scientists following the 2011 Japanese earthquake and tsunami. Credit: Oregon State University

"There is huge potential for the amount of marine debris in the oceans to increase significantly," said lead author James Carlton, an invasive species expert with the Maritime Studies Program of Williams College and Mystic Seaport in Connecticut. According to a 2015 report in Science, over 10 million tons of plastic waste enter the ocean each year, and that figure may increase 10 times by 2025. Hurricanes and typhoons, which scientists also expect to become more frequent due to climate change, also can sweep debris out into the ocean.

So far, no new species are known to have colonized the West Coast directly due to the 2011 tsunami. However, it can take years after a nonnative species first arrives to detect a newly established population. This provides a window of time for action, although the full consequences of the tsunami-driven rafting are still uncertain.

Marine sea slugs from a Japanese vessel from Iwate Prefecture, washed ashore in Oregon in April 2015. Credit: John Chapman

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

However, scientists largely agree that prevention is the most effective way to combat invasive species. Since preventing tsunamis is not an option, Ruiz suggested the main focus should be managing plastic.

Greg Ruiz, a marine invasions biologist with the Smithsonian, samples invertebrates in San Francisco Bay. Credit: Ross Whippo/Smithsonian Environmental Research Center

"There's an increasing load of plastic and microplastics at sea that are thought to have significant consequences for biology and ecology," he said. "This is one other dimension and consequence of plastics and manmade material that deserves attention."

Moss Landing Marine Laboratories, the Oregon Institute of Marine Biology and Portland State University also contributed to this report.

Explore further Invasive species danger from tsunami may not be known for years

More information: J.T. Carlton el al., "Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography," Science (2017). Journal information: Science J.T. Carlton el al., "Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography,"(2017). science.sciencemag.org/cgi/doi … 1126/science.aao1498</s>When a magnitude 9 earthquake shook the western Pacific Ocean floor and sent a tsunami crashing into Japan in 2011, millions of pieces of debris — from docks and fishing boats to plastic pollution — were swept out to sea. Now, a new study finds that nearly 300 species hitchhiked aboard that debris across the Pacific and were scattered along the west coast of North America.

The findings, published in the journal Science, conclude that 268 species of macro- and micro-invertebrates, two fish species, and 19 species of microscopic organisms called protists made their way across the Pacific in what the scientists called a “megarafting” event. They included barnacles, mussels, limpets, the Japanese barred knifejaw fish, and Japanese shipworm. The study was led by marine scientist James Carlton of Williams College.

Species catching a ride on debris across oceans isn’t a new phenomenon. In fact, most scientists believe that is how islands were colonized by new flora and fauna. But previously this “rafting” happened aboard natural debris, things like fallen trees or kelp. Man-made objects, particularly plastics, last much longer, enabling species to travel farther than ever before. This increases the chance of foreign species reaching new ecosystems and spurring an invasive species takeover.

The study authors warn that because of climate change, sea level rise, and worsening, more frequent extreme weather events, there is likely to be more debris washing into our oceans from coastal communities. The result could be a surge in megarafting events and species movement.</s>WATCH: They are alien hitchhikers. The debris swept out to sea as a result of the 2011 Japanese tsunami also transported hundreds of marine passengers. As Mary Griffin tells us, for the first time in history, nearly 300 species of these sea creatures appeared on our coast.

Henry Choong is the curator of Invertebrate Zoology at the Royal BC Museum.

On Friday, he showed CHEK News jars containing sea creatures called hydroids. They are related to jellyfish and coral. Choong is researching how they hitched a ride to the west coast on debris swept into the ocean as a result of the 2011 Japan tsunami.

"It's really allowed us to to to track this material from essentially the start of when it was deposited," Choong said.

Using a high-powered microscope, he was able to determine the origins of the hydroids.

"And here we are looking at the close-up of the essentially the skeleton of the hydroid where the polyp would have been," Choong said.

In 2011, the tsunami tore apart buildings and homes in Japan. Then the retreating waters pulled the floating debris into the Pacific Ocean. These animals attached themselves to the debris floating by and made the journey across the Pacific Ocean. Now, it's a potential threat to our eco-systems.

"You have organisms that are arriving alive. And capable of reproducing," Choong said. "So whenever you have a situation like that if you have species that are alien and potentially invasive.

 Then yes, there is that ecological concern."

Since 2012, 20 different Japanese species washed up on Vancouver Island beaches.

"We are very much part of the Pacific. And, things don't happen in isolation," Choong said. "Because when something happens, it could potentially affect us as well."

Later this year, the entire collection of 289 animals will be transported to Victoria and stored at the Royal BC Museum where researchers will spend years studying them.</s>March 11, 2011, had started like any other for thousands of mussels along the Japanese coastline, another busy day clinging to docks and straining snacks out of the water. Until 2:46 p.m. local time, that is, when two warring chunks of the Earth’s crust set off six minutes of ground-shattering quakes, then a series of gigantic waves powerful enough to crush three-story buildings and rip docks off their coastlines.

That’s when those mussels set off on an incredible adventure across the Pacific Ocean. In the six years since the tsunami, debris has landed all along the western coast of North America and on the beaches of Hawaii. And according to a new study of the tsunami’s aftermath published today in Science, just a small sample of that debris—much of it plastic—has carried living individuals of almost 300 species.

"What we report is really sort of a minimum picture of what may have arrived," James Carlton, lead author on the project and a marine ecologist at Williams College, told Newsweek. And the debris is still arriving, even today. "We had no idea it would last until 2017 and beyond, as we now expect."

The long trail of rafting debris means that hundreds of species are getting the chance to stake out a foothold in new ecosystems. Scientists have known for a long time that species hitch rides on logs, but it’s usually incredibly difficult to actually track a piece of debris from take-off to landing. "Nobody has ever witnessed these events," says Martin Thiel, an ecologist who studies species movement at the Universidad Catolica del Norte in Chile and who wasn’t involved with the study. "This is really the first large-scale event that we are basically witnessing as it unfolds."

That’s because the tsunami debris has generally been relatively easy to identify. In many cases, an entire dock or boat washed ashore, complete with registration numbers or other identifying information the scientists were able to verify with the Japanese government. The team examined 634 pieces of debris, all believed to stem from the tsunami.

Then, they tallied the animals each piece was carrying, aided by a network of 80 scientists from around the globe who identified species. The team also noted which were alive—critters from 289 species, all told. Those aren’t necessarily creatures that made the whole journey, they may also be descendents born on the voyage.

But whether long-haul travelers or newborns, that’s 289 species (and likely many more on unstudied debris) with the opportunity to try to build a new life for themselves where they landed. Most won’t make it, but several could settle down—and a couple of those could in theory become the next headline-making invasive species, able to thrive so well they make species that have been there for centuries suffer. Unfortunately, beyond species that have already invaded elsewhere, like the Mediterranean mussel, invaders don’t carry red flags—Carlton compares the process to "ecological roulette." "It's very difficult to predict what species will blossom in the absence of predators or competitors that really could be eyebrow-raisers," he says. That’s why scientists monitor coastal habitats, on the lookout for early signs of an invasion. "Should something novel show up we expect that we would hear something on a fairly timely basis." But what’s been particularly striking to scientists is how much and what kinds of debris are still washing ashore six years later. Natural debris like wood petered out after the first few years, since it breaks down en route. But thanks to our modern reliance on plastic, the debris keeps coming. "We have basically a huge armada of plastics, and those are the ones that have been making it along this very long trip," Thiel says. And tsunami debris is just one tiny portion of all the plastic in Earth’s oceans, which means the same odysseys being documented here could be more regular than we realize. "We know that plastic in the ocean is not a good thing for many different reasons, and this is one of the reasons," Thiel adds. The shift from natural debris to plastic aside, Carlton says that much of what the scientists saw wasn’t predictable. "Just when you think you've seen everything here comes something else new," he says—like a sudden rush of debris covered in sometimes hundreds of orange-spotted sea anemones that came ashore during the spring of 2016, the first time the anemone was spotted. "The tsunami event was this obviously human tragedy, but the phenomenon that [Carlton] and others were able to document gave us insight into the way that species move around in our world," says Cathryn Clarke Murray, a marine ecologist at the North Pacific Marine Science Organization in Canada, which has been supporting Carlton’s research and other projects studying the impact of tsunami debris. "It really changed our perception of coastal ecology." Carlton and Thiel both note that the study is particularly timely given the paths of Hurricanes Irma and Maria across Florida and the Caribbean, knocking plastic and other debris into the ocean as they go. That’s perfectly positioned to hitch a ride on the Gulf Stream and land in Europe. And if current trends continue, more and more of that debris will be long-floating plastic. "Really, it's a story about what the future could hold," Carlton says.
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• Fukushima Cleanup: Highly Radioactive Nuclear Fuel Will Remain in Reactors Until at Least 2023</s>WASHINGTON (AP) — Nearly 300 species of fish, mussels and other sea critters hitchhiked across the Pacific Ocean on debris from the 2011 Japanese tsunami, washing ashore alive in the United States, researchers reported Thursday.

It is the largest and longest marine migration ever documented, outside experts and the researchers said. The scientists and colleagues combed the beaches of Washington, Oregon, California, British Columbia, Alaska and Hawaii and tracked the species to their Japanese origins.

Their arrival could be a problem if the critters take root, pushing out native species, the study authors said in Thursday’s journal Science.

“It’s a bit of what we call ecological roulette,” said lead author James Carlton, a marine sciences professor at Williams College, in Williamstown, Massachusetts.

It will be years before scientists know if the 289 Japanese species thrive in their new home and crowd out natives. The researchers roughly estimated that a million creatures traveled 4,800 miles (7,725 kilometers) across the Pacific Ocean to reach the West Coast, including hundreds of thousands of mussels.

Invasive species is a major problem worldwide with plants and animals thriving in areas where they don’t naturally live. Marine invasions in the past have hurt native farmed shellfish, eroded the local ecosystem, caused economic losses and spread disease-carrying species, said Bella Galil, a marine biologist with the Steinhardt Museum of Natural History in Tel Aviv, Israel, who wasn’t part of the study.

A magnitude 9 earthquake off the coast of Japan triggered a tsunami on March 11, 2011, that swept boats, docks, buoys and other man-made materials into the Pacific. The debris drifted east with an armada of living creatures, some that gave birth to new generations while at sea.

“The diversity was somewhat jaw-dropping,” Carlton said. “Mollusks, sea anemones, corals, crabs, just a wide variety of species, really a cross-section of Japanese fauna.”

The researchers collected and analyzed the debris that reached the West Coast and Hawaii over the last five years, with new pieces arriving Wednesday in Washington. The debris flowed across the North Pacific current, as other objects do from time to time, before it moved north with the Alaska current or south with the California current. Most hit Oregon and Washington.

Last year, a small boat from Japan reached Oregon with 20 good-sized fish inside, a kind of yellowtail jack native to the western Pacific, Carlton said. Some of the fish are still alive in an Oregon aquarium. Earlier, an entire fishing ship — the Sai sho-Maru — arrived intact with five of the same 6-inch fish swimming around inside.

Co-author Gregory Ruiz, a Smithsonian marine ecologist, is especially interested in a Japanese parasite in the gills of mussels. Elsewhere in the world, these parasites have taken root and hurt oyster and mussel harvests and they hadn’t been seen before on the West Coast.

The researchers note another huge factor in this flotilla: plastics.

Decades ago, most of the debris would have been wood and that would have degraded over the long ocean trip, but now most of the debris — buoys, boats, crates and pallets — are made of plastic and that survives, Carlton said. And so the hitchhikers survive, too.

“It was the plastic debris that allowed new species to survive far longer than we ever thought they would,” Carlton said.

James Byers, a marine ecologist at the University of Georgia in Athens, who wasn’t part of the study, praised the authors for their detective work. He said in an email that the migration was an odd mix of a natural trigger and human aspects because of the plastics.

“The fact that communities of organisms survived out in the open ocean for long time periods (years in some cases) is amazing,” he wrote.

© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.</s>The 2011 Japanese tsunami set the stage for something unprecedented. For the first time in recorded history, scientists have detected entire communities of coastal species crossing the ocean by floating on makeshift rafts. Nearly 300 species have appeared on the shores of Hawaii and the U.S. West Coast attached to tsunami debris, marine biologists from the Smithsonian Environmental Research Center, Williams College and other institutions reported in the journal Science on Thursday.

The tsunami formed March 11, 2011, triggered by an earthquake of 9.0 moment magnitude that struck Japan the same day. At its tallest point, the tsunami towered 125 feet over Japan's T?hoku coast and swept millions of objects out to sea, from small pieces of plastic to fishing boats and docks. These kinds of objects, scientists said, helped the species attached to them complete the transoceanic journey.

"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 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 that opportunity on a large scale."

Scientists began finding tsunami debris washing up in Hawaii and western North America in 2012, with living organisms still attached. From 2012 to 2017, they continued to find debris, including buoys, crates, vessels and docks. In total, they detected 289 living species on tsunami debris originating from Japan, and they suspect there are far more that escaped their notice. While the arrivals have slowed down, they have not stopped. The team was still finding new species when the study period ended in 2017.

Mollusks such as mussels occurred most frequently of all invertebrate groups. Worms, hydroids (sea anemone and jellyfish relatives), crustaceans and bryozoans that form branch-like underwater colonies were not far behind. Nearly two-thirds of the species had never been seen on the U.S. West Coast. None of the species were known--or expected--to survive a transoceanic rafting voyage between continents, largely because the open ocean is considered to be a harsher environment for creatures used to more hospitable waters of the coasts. However, the slower speed of ocean rafts (1 or 2 knots, compared to 20 or more knots for commercial ships) may have allowed species to gradually adjust to their new environments. 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.

The increase in marine plastics and other more durable debris also made survival easier, according to the researchers. Much of the debris the scientists found rafted ashore was made of fiberglass or other plastic materials that do not decompose and could easily survive six or more years at sea. These materials started becoming common in the mid-20th century, and their dominance is only expected to rise.

"There is huge potential for the amount of marine debris in the oceans to increase significantly," said lead author James Carlton, an invasive species expert with the Maritime Studies Program of Williams College and Mystic Seaport in Connecticut. According to a 2015 report in Science, over 10 million tons of plastic waste enter the ocean each year, and that figure may increase 10 times by 2025. Hurricanes and typhoons, which scientists also expect to become more frequent due to climate change, also can sweep debris out into the ocean.

So far, no new species are known to have colonized the West Coast directly due to the 2011 tsunami. However, it can take years after a nonnative species first arrives to detect a newly established population. This provides a window of time for action, although the full consequences of the tsunami-driven rafting are still uncertain.

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

However, scientists largely agree that prevention is the most effective way to combat invasive species. Since preventing tsunamis is not an option, Ruiz suggested the main focus should be managing plastic.

"There's an increasing load of plastic and microplastics at sea that are thought to have significant consequences for biology and ecology," he said. "This is one other dimension and consequence of plastics and manmade material that deserves attention."

Moss Landing Marine Laboratories, the Oregon Institute of Marine Biology and Portland State University also contributed to this report.

Images are available at the Smithsonian Newsdesk (http://newdesk. ). The abstract will be available after publication at http://science. . For a full copy of the paper, images or to speak with the authors, contact Kristen Minogue at 443-482-2325 or minoguek@si.edu, or Monaca Noble at 443-482-2467 or noblem@si.edu.</s>The 2011 tsunami that struck Japan was one of the most powerful in recorded history. Now, scientists have found it sent hundreds of marine species across a transoceanic voyage from Japan to the US.

Entire communities of marine coastal organisms which originated in Japan have been detected across the beaches of Hawaii and the west coast of the US. In total, almost 300 species have been documented on the foreign shores, all attached to debris from the tsunami.

The 2011 tsunami was triggered by a M 9.0 earthquake just off the coast of Japan. The earthquake caused significant offset in the nearby seafloor, which triggered a tsunami. The earthquake was the fourth most powerful ever recorded in the world and produced a tsunami wave that reached up to 133 feet in height.

This tsunami wave caused objects across coastal Japan to be swept out to sea. Many of these objects were once in Japanese harbors: fishing boats, parts of docks, fishing equipment, etc. These makeshift rafts were used by margine species to travel across the Pacific.

The first appearance of Japanese marine organisms on America's shores was in 2012 when buoys, fishing crates, parts of docks, etc. started washing ashore. The research team collected and documented the species which travelled across the Pacific, identifying 289 in total.

Most of the species were types of marine invertebrates such as mussels, worms, sea anemones, and crustaceans. The majority of the species are not native to Hawaii or the west coast of the US, introducing new species into those ecosystems.

Surprisingly, the marine organisms which live in calm coastal waters were able to survive the treacherous multi-year journey across the Pacific. This could be due to the slow pace of the rafts, allowing the invertebrates to adjust to the new enviroment and reproduce on the debris. Most of the pieces that appeared more recently, 5+ years after the tsunami, were plastic in origin since plastic does not decompose as quickly as organic materials such as wood.

There are no currently documented new species that have colonized the west coast or Hawaii. However, researchers admit it is likely they did not capture all raft pieces and that it could take years for a new species to colonize. Thus, we will have to wait and study the coastlines for establishment of new species that once called Japan their home.</s>WASHINGTON (AP) — Nearly 300 species of fish, mussels and other sea critters hitchhiked across the Pacific Ocean on debris from the 2011 Japanese tsunami, washing ashore alive in the United States, researchers reported Thursday.

It is the largest and longest marine migration ever documented, outside experts and the researchers said. The scientists and colleagues combed the beaches of Washington, Oregon, California, British Columbia, Alaska and Hawaii and tracked the species to their Japanese origins CBS SFBayArea reported.

Their arrival could be a problem if the critters take root, pushing out native species, the study authors said in Thursday’s journal Science.

“It’s a bit of what we call ecological roulette,” said lead author James Carlton, a marine sciences professor at Williams College, in Williamstown, Massachusetts.

It will be years before scientists know if the 289 Japanese species thrive in their new home and crowd out natives. The researchers roughly estimated that a million creatures traveled 4,800 miles (7,725 kilometers) across the Pacific Ocean to reach the West Coast, including hundreds of thousands of mussels.

Invasive species is a major problem worldwide with plants and animals thriving in areas where they don’t naturally live. Marine invasions in the past have hurt native farmed shellfish, eroded the local ecosystem, caused economic losses and spread disease-carrying species, said Bella Galil, a marine biologist with the Steinhardt Museum of Natural History in Tel Aviv, Israel, who wasn’t part of the study.

A magnitude 9 earthquake off the coast of Japan triggered a tsunami on March 11, 2011, that swept boats, docks, buoys and other man-made materials into the Pacific. The debris drifted east with an armada of living creatures, some that gave birth to new generations while at sea.

“The diversity was somewhat jaw-dropping,” Carlton said. “Mollusks, sea anemones, corals, crabs, just a wide variety of species, really a cross-section of Japanese fauna.”</s>While the number of introductions which eventually lead to such invasions is rising across the globe, most accidental introduction events involve small numbers of individuals and species showing up in a new area.

But new research published today in Science has found that hundreds of marine species travelled from Japan to North America in the wake of the 2011 Tōhoku earthquake and tsunami (which struck the east coast of Japan with devastating consequences).

Marine introductions result from biofouling, the process by which organisms start growing on virtually any submerged surface. Within days a slimy bacterial film develops. After months to a few years (depending on the water temperature) fully formed communities may be found, including algae, molluscs such as mussels, bryozoans, crustaceans, and other animals.

Current biosecurity measures, such as antifouling on ships and border surveillance, are designed to deal with a steady stream of potential invaders. But they are ill-equipped to deal with an introduction event of the scale recorded along most of the North American coast. This would be just as true for Australia, with its extensive coastlines, as it is for North America.

This research, led by James Carlton of Williams College, shows that over a few years after the 2011 earthquake and tsunami, many marine organisms arrived along the west coast of North America on debris derived from human activity. The debris ranged from small pieces of plastic to buoys, to floating docks and damaged marine vessels. All of these items harboured organisms. Across the full range of debris surveyed, scores of individuals from roughly 300 species of marine creatures arrived alive. Most of them were new to North America.

The tsunami swept coastal infrastructure and many human artefacts out to sea. Items that had already been in the water before the tsunami carried their marine communities along with them. The North Pacific Current then transported these living communities across the Pacific to Alaska, British Columbia, Oregon, Washington and California.

What makes this process unusual is the way a natural extreme event – the earthquake and associated tsunami – gave rise to an extraordinarily large introduction event because of its impact on coastal infrastructure. The researchers argue that this event is of unprecedented magnitude, constituting what they call "tsunami-driven megarafting": rafting being the process by which organisms may travel across oceans on debris – natural or otherwise.

It's not known how many of these new species will establish themselves and spread in their new environment. But, given what we know about the invasion process, it's certain at least some will. Often, establishment and initial population growth is hidden, especially in marine species. Only once it is either costly or impossible to do something about a new species, is it detected.

Biosecurity surveillance systems are designed to overcome this problem, but surveillance of an entire coast for multiple species is a significant challenge.

Perhaps one of the largest questions the study raises is whether this was a once off event. Might similar future occurrences be expected? Given the rapid rate of coastal infrastructure development, the answer is clear: this adds a new dimension to coastal biosecurity that will have to be considered.

Investment in coastal planning and early warning systems will help, as will reductions in plastic pollution. But such investment may be of little value if action is not taken to adhere to, and then exceed, nationally determined contributions to the Paris Agreement. Without doing so, a climate change-driven sea level rise of more than 1 m by the end of the century may be expected. This will add significantly to the risks posed by the interactions between natural extreme events and the continued development of coastal infrastructure. In other words, this research has uncovered what might be an increasingly common new ecological process in the Anthropocene – the era of human-driven global change.

Explore further: Tsunami enabled hundreds of aquatic species to raft across Pacific</s>Well after the massive 2011 tsunami that swept across the Japanese coast, reminders of the event started appearing on the US-side of the Pacific. Various forms of debris, ranging from small hunks of plastic up to entire boats, made appearances on the US West Coast. Now, a team of researchers has found that the floating debris carried hundreds of potentially invasive species across the vast ocean with it, including a couple of species of fish.

While large tsunamis have occurred frequently, even in historic times, there's no indication of anything like this before. The difference, according to the researchers, is humanity's ability to make materials that can remain afloat in the open ocean for years.

It may seem a bit surprising that marine species couldn't just introduce themselves, given that they already live in the ocean. But coastal habitats are very distinct from those of the open ocean, and many species couldn't survive an ocean crossing on their own even if currents were favorable. While there are coastal environments across the Pacific Rim, they occur at very different latitudes, meaning the temperature conditions and nutrient availability can provide barriers to any species that might migrate around the edges of the open ocean.

The clearest indication that the Pacific poses a major barrier is the fact that similar environments, like the coasts of Japan and the Pacific Northwest, have distinct species.

But that barrier broke down a bit in the wake of the 2011 tsunami. The ocean carried off all sorts of floating debris, from small objects like buoys and wooden beams to entire docks and boats. Since 2012, a group of biologists has been monitoring the debris, tracking the organisms it carries. All told, they found 289 species. Most of these were invertebrates, like mollusks, worms, and crustaceans. But there were at least two species of fish that hitched a ride (one floating inside a flooded portion of a ship hull). And as of late last year, new debris was still arriving—including new boats, although the frequency was going down. "It is surprising that living species from Japan continue to arrive after nearly six years at sea," the authors write, "four or more years longer than previous documented instances of the survival of coastal species rafting in the ocean."

Most of these ended up in Washington and Oregon, but Alaska, California, and Hawaii have also seen species-rich debris.

In some cases, the species have a short enough life span that they had to have gone through multiple generations during the time they were floating across the Pacific, and the population on the debris contained individuals at various ages. So, they've been breeding during their travels, which means they are arriving on US shores in good shape to colonize these areas. Half the species the team identified were only seen on a single piece of debris, which suggests that even more species have made the trip but gone undetected.

The aspect that makes this unique is the fact that many of the materials that made the trip successfully were artificial. Some wooden beams managed it, but their presence dropped off quickly in part because the species that colonized them included worms that feed on the wood. By contrast, a lot of the material that's continuing to arrive is plastic or floats because of the presence of extruded polystyrene. Most of the boat hulls were fiberglass.

None of these materials were common at the time of earlier Japanese tsunamis of this size, so the authors conclude that this is a species exchange without any historic precedent.

Right now, it's too soon to tell if any of the species that made the trip have settled into their new environment. But lag times for new species introductions can be years or decades, as it takes time for populations to become established enough to be detectable. But these results indicate we should definitely be on the lookout for new arrivals—and any ecological challenges they might bring with them.
Aquatic species from Japan hitched a ride on debris from the 2011 Tōhoku earthquake and tsunami and were able to reach the West Coast of the United States alive.