The
spread of invasive biological species may be the next item on the list of
potential global threats caused by the Japanese tsunami of March 2011.
The spread of invasive biological species may be the
next item on the list of potential global threats caused by the Japanese
tsunami of March 2011.
Prior to this report, the after-effects of the
Japanese earthquake and tsunami disaster on March 16, 2011 had already stirred
up anxiety within the global community over the detrimental effects of
radiation and chemical contamination.
A September
2011 report in PLoS ONE showed that the Fukushima
Dai-ichi reactor accident fallout extended as far as the San Francisco Bay area
in California, although the levels of radioactive material were very low and
posed no health risk to the public.
Now, it seems that part of the debris from the disaster
has arrived at the shores of the West Coast of the United States with new
visitors – invasive species.
When a floating dock was found washed ashore in
Newport two weeks ago, marine biologists traced it back to the Japanese
disaster and unexpectedly found a thriving and dense community of non-native
species on the float.
The team at Oregon State University’s (OSU) Hatfield
Marine Science Center were surprised to discover a dense fouling community on
the flat, averaging about 13 pounds of organisms per square foot.
They collected samples of 4-6 species including
barnacles, starfish, urchins, limpets, algae, amphipods, and mussels. In total,
they estimate that dozens of species have amassed on the float.
What was puzzling to the scientists was how the species
managed to survive on their journey across the Pacific Ocean without food for
months. Possible reasons include species adaptability and milder conditions at
sea than expected.
“Drifting boats lack such dense fouling communities,
and few of these species are already on this coast. Nearly all of the species
we’ve looked at were established on the float before the tsunami; few came
after it was at sea,” said John Chapman, an OSU marine invasive species
specialist.
One species that stood out was brown algae (Undaria
pinnatifida), commonly referred aswakame, which is a popular type of
seaweed consumed by the Japanese. The cement dock was predominantly covered by
the brown algae, which raised alarm bells for the scientists. Prior to the
discovery of algae on the float, the species had not been reported in the north
of Monterey, California.
Marine ecologists regard invasive marine species –
commonly introduced via ballast water from ships – as a bane to the ecosystem
on West Coast. Not only do these species threaten the ecosystem by outcompeting
native marine communities for survival, they also pose a threat to the economy
that thrives on these native marine species, which might disappear as a result.
“We have no evidence so far that anything from this float
has established on our shores,” said Chapman. “That will take time. However, we
are vulnerable. One new introduced species is discovered in Yaquina Bay, only
two miles away, every year. We hope that none of these species we are finding
on this float will be among the new discoveries in years to come.”
According to the team, it is not easy to assess how
much of a threat the species may present. Additional species might be
introduced in the future as more debris wash up ashore.
Interestingly, they noted that the dock might
represent submerged debris in Japan, and therefore contain a uniquely,
well-established subtidal community.
According to Chapman, floating objects from near
Sendai could have drifted from the coast into the Kuroshio current before entering
the eastern Pacific. The team hopes to sample similar floats found in Japan and
compare their findings with those found on the cement dock.
——
Source: OSU
No comments:
Post a Comment