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<DIV class=article-heading><FONT size=4>Tsunami triggers invasion
concerns</FONT></DIV></HGROUP>
<DIV>Biologists track species on flotsam from Japan to US shores.</DIV>
<DIV><SPAN class=vcard><A class=fn
href="http://www.nature.com/news/tsunami-triggers-invasion-concerns-1.12538?WT.ec_id=NATURE-20130307#auth-1">Virginia
Gewin</A></SPAN></DIV><TIME datetime="2013-03-06" pubdate>
<DIV class=journal-title>Nature Volume:495<SPAN>, </SPAN><ABBR
title="Digital Object Identifier">doi</ABBR>:10.1038/495013a</DIV>
<DIV></SECTION>06 March 2013</DIV>
<DIV><A
href="http://www.nature.com/news/tsunami-triggers-invasion-concerns-1.12538?WT.ec_id=NATURE-20130307">http://www.nature.com/news/tsunami-triggers-invasion-concerns-1.12538?WT.ec_id=NATURE-20130307</A></DIV>
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<DIV style="MAX-WIDTH: 632px" class=caption><FONT size=1>A worker in Newport,
Oregon, burns debris off a Japanese concrete dock that washed across the
Pacific. </FONT><FONT size=1>Oregon Parks and Recreation </FONT></DIV>
<DIV class=caption><FONT size=1>Dept/AP Photo</FONT></DIV>
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<DIV class=article-tools>When a 165-tonne block of concrete and steel crashed
into the central Oregon coast last June, Jessica Miller was shocked to find that
the structure — a dock that had washed across the Pacific from Misawa, Japan —
was teeming with life after 15 months at sea. “It was surreal,” says
Miller, a marine ecologist at Oregon State University’s Hatfield Marine Science
Center in Newport. She found tens of thousands of organisms on the structure in
layers up to 15 centimetres thick, including brown algae, pink barnacles
and shrimp-like creatures called caprellids. In December 2012, a second large
Japanese dock landed in Washington state laden with species. Other debris,
including derelict boats and buoys harbouring live organisms, continues to wash
up on the shores of Oregon, Washington and, most recently, Hawaii.</DIV>
<DIV class="related-stories-box box"> </DIV>
<DIV class="related-stories-box box">Almost two years after the Tohoku
earthquake triggered a devastating tsunami, North American shores are awash in
debris swept from the Japanese coastline some 8,000 kilometres away. The
flotsam constitutes floating islands of species — some of which could
potentially be invasive. According to estimates from the Japanese government,
the tsunami carried about 1.5 million tonnes of debris out to sea. “We
expect to see tsunami debris for years to come,” says Peter Murphy of the
National Oceanic and Atmospheric Administration (NOAA) in Silver Spring,
Maryland, who is the Alaska coordinator for NOAA’s marine debris
programme.</DIV>
<P class="content no-heading cleared main-content">The tsunami has sparked
several unanticipated experiments. Biologists have seized on the
unprecedented opportunity to track a potential species invasion from the
beginning, and oceanographers have used the debris sightings to refine their
models of the effects of winds and currents on debris. Marine ecologists,
meanwhile, are tracing fish migrations using radioisotopes released from the
tsunami-triggered accidents at the Fukushima nuclear reactors.</P>
<P class="content no-heading cleared main-content">“The tsunami debris is an
unparalleled scientific opportunity, specific in time and place,” says Susan
Williams, a marine ecologist at the University of California, Davis.</P>
<P class="content no-heading cleared main-content">The invasion biologists have
perhaps had the most urgent call to action, because no one anticipated that
coastal species would survive such a long journey across the open sea. “This is
an event so rare we simply don’t expect to see it,” says James Carlton, an
invasive-species expert from Williams College in Williamstown,
Massachusetts, who has teamed up with Miller and other colleagues to study the
arrivals.</P>
<P class="content no-heading cleared main-content">Researchers must first
confirm that the debris they are studying really is from the tsunami. Water
bottles with Japanese characters offer a clue. Registration numbers on boats can
be traced back to those that were reported missing. But of the 1,500 or so
reported items that have washed up in recent months, only 21 have been
confirmed by the Japanese consulate, according to Murphy.</P>
<P class="content no-heading cleared main-content">The arrival of potentially
invasive species is not a new concern on the Pacific coast. Organisms can be
transported on transoceanic boats or in their ballast water. But boats do
not typically recruit whole communities, and they move too fast between ports
for many organisms to hang on. The resident coastal communities transported on
slow-moving tsunami debris therefore look very different — and can arrive along
the whole North American coastline rather than just at heavily monitored ports.
No invasions have yet been detected from the tsunami debris, but it is unlikely
that Carlton, Miller and their team are aware of every single landfall, so a
potentially invasive species could well have been missed.</P>
<P class="content no-heading cleared main-content">The team’s next step is to
determine which organisms survived the journey across the Pacific, and how. In
the nine months since the first dock made landfall, the team has identified
roughly half of the 175 species found so far on all debris items. John Chapman,
a marine biologist also at Hatfield Marine Science Center, will go to Misawa
later this month to document which species reside on docks there in early
spring, the season when the tsunami struck.</P>
<P class="content no-heading cleared main-content">The results so far suggest a
real risk of invasion. For example, three of the best-known algal invaders have
been among the debris, says Gayle Hansen, a marine-algae expert at Oregon State
University who is based in Newport. She says that 75% of the 46 algal species
she has collected from the debris so far have been reproductively active,
dropping spores. That gives them a good chance of getting established and
possibly displacing native species in the Pacific Northwest.</P>
<P class="content no-heading cleared main-content">State officials, who are
usually first on the scene, are often quick to destroy any organisms clinging to
debris to avert potential invasions. That can make it challenging for Carlton’s
team to get samples. But the problem is easing, Carlton says, as more responders
become aware of the need to sample the arrivals. He adds that there have been
few reports of debris with living Japanese species from Alaska, British Columbia
and California, which could represent a lack of reporting, or an artefact of
oceanography.<A name=map></A></P>
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<DIV class=lightbox-icon><A class="lightbox-link hide-text" title=Expand
href="javascript:;">Expand</A></DIV>
<P style="PADDING-RIGHT: 25px" class=credit>SOURCE: NOAA</P></DIV></DIV>
<P class="content no-heading cleared main-content">The recent spike in debris
landings is to be expected during winter and spring, owing to large-scale
patterns of currents and winds. The path of debris flows north of Hawaii (see <A
href="http://www.nature.com/news/tsunami-triggers-invasion-concerns-1.12538?WT.ec_id=NATURE-20130307#map">‘Tsunami
invasion’</A>) and was predicted by NOAA models, which have incorporated
sightings from mariners. But Nikolai Maximenko, an oceanographer at the
University of Hawaii in Honolulu, says that the exact landfall for the concrete
docks was difficult to predict because they are buoyant enough that the effects
of winds and currents are comparable in strength.</P>
<P class="content no-heading cleared main-content">Maximenko is also helping to
sample the plume of Fukushima radioisotopes, which lags behind the debris and is
slowly moving east. The radioisotopes are assisting ecologists. In February,
Nicholas Fisher, a marine scientist at Stony Brook University in New York, and
his colleagues showed that two radioisotopes, caesium-134 and caesium-137, could
be used to trace the past movements of bluefin tuna between Japan and California
(<A href="http://doi.org/kn9">D. J. Madigan <I>et al. Environ.
Sci. Technol. </I>http://doi.org/kn9; 2013</A>). Fisher’s team confirmed the
presence of both caesium isotopes in bluefin tuna arriving from Japan — although
the levels pose no health risk to humans. “We see evidence that fish might cross
the Pacific in about one month, which we found amazing,” says Fisher.</P>
<P class="content no-heading cleared main-content">Other researchers from Oregon
State University in Corvallis and NOAA are using the technique to determine
whether there are two different stocks of North Pacific albacore tuna, which
would be reflected in each population’s isotopic profile. Fisher’s team also
wants to use this method to track the migratory patterns of other large marine
animals, such as albatrosses, loggerhead turtles and salmon sharks.</P>
<P class="content no-heading cleared main-content">Even as researchers track
species using radioisotopes and count them on debris, they bear in mind the
tsunami’s staggering human toll. “This is the experiment that never should have
taken place,” says Chapman.</P></FONT></DIV></BODY></HTML>