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Help from Kelp

Measuring radioactivity from the Fukushima Plant in California’s coastal waters

By Charlotte Stevenson, University of Southern California Sea Grant

Toothpaste. Ice cream. Radioactivity dosimeter. What could these three things possibly have in common? The answer: kelp.

Kelp? The name refers to a group of large brown seaweeds, which are known for the gorgeous underwater forests and canopies they form along California and the rest of the temperate Pacific coastline. You may know that extracts from kelp are found in dozens of products and foods upon which we depend, but did you know that kelp is helping scientists measure radioactivity from the Fukushima Daiichi Nuclear Plant in our coastal waters?

University of Southern California (USC) Sea Grant is helping to fund Kelp Watch 2014, a research initiative started by Dr. Steven Manley of California State University Long Beach in collaboration with Dr. Kai Vetter, Professor of Nuclear Engineering at UC Berkeley and Head of Applied Physics Program at Lawrence Berkeley National Laboratories (LBNL). The project is using fast growing kelp forest species (Macrocystis pyrifera aka Giant kelp and Nereocystis luetkeana aka bull kelp) as living dosimeters of the Fukushima released radioisotopes (primarily 134‐Cesium and 137‐Cesium), predicted to arrive along the North American coast via ocean currents by mid‐2014.

USC Sea Grant initially funded an emergency pilot study for Dr. Manley in 2011, which detected radioactive iodine (I-131) in kelp when the atmospheric plume from the damaged Fukushima plant deposited these radioisotopes on California coastal waters via atmospheric transport and rainfall just 10 days after the March 2011 Japanese earthquake and subsequent tsunami (Manley & Lowe, 2013).

Understandably, the word “radioactivity” quickly raises important red flags for Californians: Is it safe? Should we be worried? Since 2011, Dr. Manley has fielded hundreds of emails and phone calls from the concerned general public. “When the public is clearly so concerned, it is important to provide people with quick, scientifically accurate information,” said USC Sea Grant’s Associate Director, Phyllis Grifman.  And that is one of the primary goals of Kelp Watch 2014.

Now, with predictions of radiation reaching the California coast via ocean currents, Dr. Manley hopes Kelp Watch 2014 will provide the public with immediate data as to whether there are any direct human health risks to the small amounts of radioactivity in the ocean. However, Dr. Manley and his colleagues are also interested in the extent to which these radioisotopes have entered the highly productive and complex kelp forest ecosystem.

This is not the first time that radioactive isotopes have been detected in seaweed. In fact, marine brown seaweeds are known for their rapid growth rate and rapid concentration of Cesium (Cs), Strontium (Sr) and Iodine (I) in their tissues, among many other elements. Radioactive cesium (Cs-137) from nuclear weapons testing during the 1950s and Chinese nuclear tests in the late 1970s were detected many years later in Asian kelp species. Two months after the Chernobyl nuclear disaster in April 1986 in Ukraine, 137-Cesium was detected in non-kelp seaweeds throughout the coastal northern hemisphere waters; a detailed study showed the levels were detectable in the seaweeds for 40 days. For Kelp Watch 2014, Dr. Vetter with LBNL is using unprecedented, state-of-the-art, low-detection-limit analysis of the collected kelp.

In the space of a few months, this project has impressively gone from being the idea of a single scientist in Long Beach, California to being an international, collaborative, research project with over 40 scientists, institutions, federal agencies (NOAA, National Park Service), small educational foundations, and even a private seaweed harvesting company. At distinct time points in 2014, this collaboration will collect kelp from sites in the Aleutian Islands, down through Mexico and even in Chile. Two tropical locations, Hawaii and Guam, have been added, and although kelps are not found there, a related brown seaweed will be sampled to try to track the movement of the radiation currents across the Pacific. “I haven’t been this enthusiastic for a project in many years,” says Dr. Manley. “I do not know if there has been such a large unified scientific effort of this kind ever, especially involving kelp!”

USC Sea Grant is proud to be a financial supporter and kelp collection participant in such a collaborative, scientific project with incredible public transparency and interaction. Dr. Vetter’s group is hosting a public website where all data and updates are posted. Look for the first release of results from the first round of collection this May 2014 on and @KelpWatch2014 on Twitter.

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