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Tuesday, May 29, 2012

Connectivity

This morning there was an article in the San Francisco Chronicle describing a research paper that found Cesium-137 from the Fukushima Dai-ichi nuclear disaster in Pacific Bluefin Tuna (Thunnus orientalis) off the California coast. 

Adult Pacific Bluefin Tuna spawn in the western Pacific off Japan, then juveniles migrate to the eastern Pacific off California.  Scientists sampled muscle tissue from bluefin tuna caught near San Diego in August 2011 (three months after the earthquake and tsunami).  They found Cesium-137 levels ten times higher than in previous years.  (Note that although elevated, these levels were far below the safety limits for human consumption.)

Although I have yet to see a Pacific Bluefin Tuna, they occur off the central California coast, especially in fall.

Here's a photo of me with an Atlantic Bluefin Tuna (Thunnus thynnus) on South Monomoy Island in Chatham, MA,  in 1993.



In March, Claudia sent me an article about radioactive kelp.  Researchers sampled Giant Kelp (Macrocystis pyrifera) in southern and central California in April 2011, one month after the nuclear accident.  They found elevated levels of Iodine-131 (radioiodine).  In this case, the Iodine-131 was released into the atmosphere and then deposited in surface waters with precipitation.  (Kelps accumulate iodine and store it as iodide which functions as an antioxidant.)  Four weeks after the initial collection and measurement, Iodine-131 was no longer detectable.

Giant Kelp grows near the entrance to Bodega Harbor and also washes up as drift algae on local beaches.  Here are a few photos (taken along the Big Sur and Monterey coasts).


The presence of radioactivity from a nuclear disaster in Japan in animals and algae off the California coast is testament to connectivity across the entire Pacific Ocean basin.  


Madigan, D.J., Z. Baumann, and N.S. Fisher.  2012.  Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California.  PNAS Early Edition, 29 May 2012: 1-4.

Manley, S.L. and C. Lowe.  2012.  Canopy-forming kelps as California’s coastal dosimeter: Iodine-131 from damaged Japanese reactor measured in Macrocystis pyrifera.  Environmental Science and Technology 46: 3731-3736.

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