Tsunami Debris From Japan Carries Biological Species To California

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.

AsianScientist (Jun. 19, 2012) – 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.

Cement dock washed ashore in California (Source: OSU).

One species that stood out was brown algae (Undaria pinnatifida), commonly referred as wakame, 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; Photos: OSU/Flickr.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Yuka graduated with a BSc (Hons) in life sciences from the National University of Singapore (NUS), Singapore, and received her MSc in cancer biology at University College London, UK.

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