Scientists Find Post-Tsunami Radiation in Sea Kelp, Seek to Expand Research

Scientists found radioactive kelp locally following Japan nuclear disaster

Two scientists who found radiation in sea kelp along the Southern California coast after Japan’s 2011 tsunami-induced nuclear disaster now hope to study whether contamination may be present in fish such as opaleye and other ocean creatures, including lobster and sea urchin.

The two researchers – from California State University, Long Beach – are hoping to expand on their recently published study showing that giant kelp contained up to 250 times the normal levels of a radioisotope of iodine in the weeks after last year's earthquake and resulting tsunami severely damaged Japan’s Fukushima Dai-ichi Nuclear Power Plant.

Kelp is the tall, wavy, brown algae that provides near-shore habitat for many marine species, some of which eat the plant.

Tests showed that contamination in the kelp was gone within a month, and there’s no risk to humans from the Iodine-131 radiation. Still, the research indicates that radiation from the damaged Japanese nuclear facility reached California.

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“Of course it’s cause for concern – because you don’t find this naturally in kelp or fish. It can’t be a positive thing. It also tells you that what happens half a world away can be detected,” said Cal State biology professor Steven Manley, a co-author of the study.

Manley and his co-author, marine biology professor Chris Lowe, hope next to find out whether other kinds of nuclear contamination – two radioisotopes of cesium that break down much more slowly than the Iodine-131 – are found in California marine life, including kelp and fish.

Those two cesium radioisotopes were found to contaminate waters around Japan, according to preliminary results of a study published this week by an international team of scientists.

“Our coastal environment is pretty complex. We get a lot of our food out there,” Manley said. “We should be monitoring it for these radioisotopes.”


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Lowe wants to trace the concentration of radioactive cesium up the food chain in Southern California.

“Our question is: How much gets into the ocean? Kelp is really kind of the basis for the food web and is important habitat for many of our coastal marine animals,” Lowe said. “The next step is to look at organisms that eat kelp. “

Kelp is consumed by sea urchin and some fish, including opaleye, halfmoon and senorita, according to the study. Urchin are in turn eaten by lobster and some large fish species that could be consumed by humans.

Getting funding for the future research shouldn’t be a problem, given the attention that Lowe and Manley have gotten for their recent study, which was published last month in the journal Environmental Science & Technology. The study was first reported by nonprofit Environmental Health News and on Scientific American’s website.

A month after the earthquake after Japan, the Long Beach pair obtained kelp samples from seven sites along the coast: the Palos Verdes Peninsula in Los Angeles County; Crystal Cove, Laguna Beach and Corona del Mar in Orange County; and farther north in Santa Barbara, Pacific Grove and Santa Cruz.

Kelp from Corona del Mar had the highest concentration of radioactive iodine, up to 250 times the amount found in kelp before the Japanese nuclear reactor spewed radiation in the atmosphere.

Lowe said they believe the Corona del Mar site was more contaminated because a lot of urban runoff goes through the area – meaning radiation-contaminated rain would have accumulated there.

The scientists chose to study kelp – which grows from the ocean floor up to the surface, where it floats – because it is especially good at absorbing iodine from both the water and the atmosphere.

Lowe compared kelp to the badge that X-ray technicians where to show how much radiation they’ve been exposed to.

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