An unidentified substance has killed or injured hundreds of birds so far.
Radiation from the Fukushima nuclear power plant in Japan has not reached the California coastline. Scientists monitoring kelp forests on the West Coast announced their results on Wednesday.
Scientists are testing samples and using models to try to zero in on when it will reach the California coast and how much there will be when it does.
Researchers are launching a new project to monitor California's kelp forests for radiation from the Fukushima nuclear power plant in Japan. Scientists will fan out along the California coast to collect kelp and find out if it has absorbed any radiation from the 2011 meltdown.