Using animals as environmental indicators is not a new idea, particularly when it involves studying the after effects of radiation. The flora and fauna in and around the site of the 1986 Chernobyl disaster have been studied for years.
Now it is Fukushima's turn to be studied. Starting a few months after March 11, 2011, when the Fukushima Daiichi Nuclear Power plant disaster occurred, University of South Carolina biologist Tim Mousseau and his colleagues have been monitoring the avian population
in and around the Fukushima plant.
Lasting three years, and studying the populations of bird species at over 400 sites around Fukushima, Dr. Mousseau's team found that half the populations of 57 species of birds had suffered declines. But what they discovered is very interesting. The populations have continued to decline, even though the radiation threat has dropped.
"There are dramatic reductions in the number of birds that should be there based on the overall patterns," Mousseau told CBS News
. "In terms of barn swallows in Fukushima, there had been hundreds if not thousands in many of these towns where we were working. Now we are seeing a few dozen of them left. It's just an enormous decline."
Not only have barn swallows been hit hard, but so have the great reed warbler, Japanese bush warbler, and the meadow bunting. Researchers are working to pinpoint the exact cause of the continuing decline.
Earlier field work by Dr. Mousseau showed the nuclear disaster had severe effects on a wide range of species, causing genetic damage to butterflies, monkeys, and other creatures.
Disputing the results of Mousseau study
In 2000, Robert Baker and Ron Chesser of Texas Tech University published a paper
saying the Chernobyl nuclear disaster site had turned into a marvelous "game preserve," thanks to the absence of humans.
Both men assert that in the long term, biodiversity and the abundance of species at Chernobyl and Fukushima are not being affected by radiation. “Despite our best efforts, post-accident field studies aren’t sufficient to give us a clear picture,” says Chesser. “They offer no good controls because we aren’t working with data from before the accident.”
Mousseau found patches of bleached-white feathers on many of the birds he captured at Fukushima, and this told an important story. “The first time I went to Chernobyl in 2000 to collect birds, 20 percent of the birds [we captured] at one particularly contaminated farm had little patches of white feathers here and there—some large, some small, sometimes in a pattern and other times just irregular,” said Mousseau.
The white patches
are believed to be due to radiation-induced oxidative stress. This stress depletes the bird's reserves of the antioxidants that control the color of feathers and other body parts. It was also found and documented that birds suffered other abnormalities
from radiation exposure, including cataracts, tumors, asymmetries, developmental abnormalities, reduced fertility and smaller brain size.
Mousseau thinks the studies at both Chernobyl and Fukushima are evidence of the cumulative effects of prolonged radiation exposure on wildlife at different stages after a nuclear disaster. Jim Smith, the editor and lead author of Chernobyl: Catastrophe and Consequences,
says he doesn't believe the white patches have anything to do with radiation because the levels are considered "low-dose." He remarks, " This would mean the white feather patches—and perhaps the overall bird declines—are being caused by something other than radiation."
But Mousseau is sticking to his belief that something is, indeed going on
. He says, "The relationship between radiation and numbers started off negative the first summer, but the strength of the relationship has actually increased each year. So now we see this really striking drop-off in numbers of birds as well as numbers of species of birds. So both the biodiversity and the abundance are showing dramatic impacts in these areas with higher radiation levels, even as the levels are declining."
The question on many people's minds is this: If radiation isn't causing the decline in the bird populations at Fukushima, then what is causing the decline?
Dr. Tim Mousseau's paper was published in the Journal of Ornithology
, March 17, 2015, under the title: Cumulative effects of radioactivity from Fukushima on the abundance and biodiversity of birds