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Environmental Sciences: General
Chernobyl and Fukushima: Differences and Similarities, a Biological Perspective
Timothy A. Mousseau1 and Anders P. Møller2
1: Department of Biological Sciences, University of South Carolina, Columbia, SC USA, 29208; email:Mousseau@sc.edu

2: Laboratoire d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F91405, Orsay Cedex, France; email: anders.moller@u-psud.fr

INTRODUCTION
Until very recently, the environmental, and to alesser extent, the health hazards related to nuclear
accidents have been very difficult to assess. In fact,
it has been suggested that the plant and animal life of
the Chernobyl Exclusion Zone is thriving in theabsence of human activity in the region and thatmuch of the human morbidity linked to Chernobyl
fallout was largely related to stress and other selfdestructive
behaviors(e.g.
smokingandalcoholism)[1]. Unfortunately, these conclusions
were based primarily on an absence of information
related to these issues rather than any rigorous
supporting data, and many recent reports have called
into question the validity of these conclusions as wellas the motives for their presentation[2].
In direct response to the optimistic forecasts of
the Chernobyl Forum[1] concerning wildlife, a seriesof basic ecological, genetic, and evolutionary studies
were initiated in 2005 by an international team ofbiologists (the Chernobyl Research Initiative, CRI, at
the University of South Carolina)[3] to rigorously
assess the impacts of the disaster on animalabundances and biodiversity within the Chernobyl
Exclusion Zone. This initiative was expanded in2011 to include the impacts of the Fukushimadisaster on wildlife in contaminated areas of Japan.
Although the Fukushima accident is a terrible
disaster, it has offered an opportunity for replicationof studies conducted at Chernobyl. Because both
Chernobyl and Fukushima are located in the same
zoogeographic zone, numerous species co-occur inboth regions implying that the effects of radiation onabundance,morphology,physiology
anddevelopment can be investigated with the same
techniques, and even by the same scientists. We haveexploited this unique situation in an attempt todevelop a rigorous understanding of the scope, scale,and time frame for biological responses tocontamination by radionuclides. Of particular
relevance is that these studies have been conductedunder otherwise natural settings in a manner that
permits assessing effects for wild, free livingorganisms. This is significant given that it is now

widely appreciated that natural populations often
respond very differently to stress than either
laboratory or mesocosm study animals[4,5]. To date,
the CRI research team has generated more than 40
peer-reviewed scientific publications related to thistopic. Most of these papers can be viewed on theCRI website [3].
RESULTSThe overwhelming conclusion from this recent
series of studies is that there is no evidence to suggestthat animals are doing better inside the Chernobyl
Exclusion zone. In fact, most of the organisms
surveyed have shown large drops in abundance witha consequent drop in overall biodiversity incontaminated regions of the exclusion zone. It is notknown if animal abundances in “clean” parts of theexclusion zone are higher than surrounding areas
outside of the zone but this has little bearing on theprimary question of interest which is whether or notthere is any evidence for injury to any components ofthe ecosystem that are related in to exposure toradionuclides. The evidence from replicated andrepeated independent observations is that abundancesand biodiversity drop in relation to contaminationlevels. For example, the forest bird community
showed a two-thirds drop in total abundance and a
50% drop in species richness in the morecontaminated areas when compared to clean areas
within the zone [6-8]. These patterns are consistentfrom year to year [8], although overall abundances
show annual changes largely reflecting climaticeffects in both Ukraine and in overwintering areasthat could mask local patterns of variation if studies
were not conducted with care over multiple years.
Similar patterns of decline have also been seen forbirds of prey, although there is a suggestion that
numbers are rising for this group in the relatively“clean” areas outside the Exclusion Zone [9].
Bird communities were also surveyed in
Fukushima prefecture in July, 2011, roughly fourmonths following the disaster at the Fukushima
Daiichi Nuclear Power Plant [10]. Significant
declines in abundances were noted for many species

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Environmental Sciences: Generalwith the magnitude of effect approximately double inFukushima when compared to the same species
inhabiting the Chernobyl region, pointing either tostrong effects of acute exposure, some level ofadaption to radionuclides in the Chernobyl
populations, or differing effects of the different
mixtures of radioactive chemicals that the animals
were exposed to. For example, in Fukushima, birds
were likely initially exposed to high levels ofradioactive iodine (I-131)[11] and noble gases (e.g.
Xenon-133) in addition to radioactive cesium
isotopes (Cs-134 and Cs-137)[12]. The cesium
isotopes will likely persist at high levels in the region
for many years because of their longer half-lives (2and 30 years, respectively). In contrast, radioactiveiodine (I-131) and noble gasses have long sincedisappeared from the Chernobyl region, althoughstrontium-90 and several isotopes of plutonium (e.g.
Pu-238, Pu-239, Pu-240 and Pu-241) persist andamericium-241 is increasing in the environment [13].
These differences in the present radioactive
environments between Fukushima and Chernobyl
reflect the different time periods since the disasters(1986 vs. 2011) and characteristics of the accidents.
The insect communities have also been
intensely investigated with surveys of diversity andabundances conducted in 2006-2009 in Ukraine andBelarus and in 2011 in Japan. In the Chernobylcontaminated regions of Ukraine and Belarus, wheremore than 20 generations of exposure had passed at
the time of these surveys, almost all insect groups
showed dramatic declines in areas of significant
contamination. Bees, grasshoppers, dragonflies,moths and butterflies all showed reduced numbers inareas of high contamination [8,14] with consequent
ecosystem-level effects on fruit trees [15]. Spiders
also showed major declines proportional to the levelof contamination in Chernobyl[14]. However, inFukushima, as of July 2011, only butterflies, and to alesser extent, cicadas, showed significant and obvious
declines in areas of contamination, with noimmediate effects detectable using simple survey
methods for grasshoppers, bees, or dragonflies [16].
Curiously, spiders showed a significant rise in
numbers, perhaps reflecting an absence of predators(e.g. birds) or an increased facility for capturing prey(e.g. moths and butterflies) that may have been
incapacitatedby
exposure
toradioactive
contaminants [16]. These surveys of animalabundance and biodiversity were repeated during thesummer of 2012 to assess repeatability of patterns
among years for Fukushima populations.
Many of the likely causes of the observed
declines in animals in Chernobyl have been
documented and include reduced survival andlongevity [17,18], high rates of developmental

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abnormalities (including tumors)[19], reduced
fertility [20,21], reduced cognitive abilities (perhaps
caused by smaller brains in Chernobyl birds)[22],among other likely mechanisms. Many of theseeffects can be attributed to the significantly elevatedmutation rates that have been reported for many
Chernobyl populations [23,24] It seems possible thatmany of the effects that have been observed in
Chernobyl but not yet seen in Fukushima are theproduct of multiple generations of exposure andconsequent mutation-accumulation rather than theeffects of acute exposure [25] although a recent studyof butterflies from Fukushima [26] has foundconclusive evidence of genetically based mutations
that have increased over time.
It has been sometimes suggested that thecontamination levels currently observed in Chernobyl
and Fukushima are generally quite low and lower
than many of the naturally radioactive locations in
the world (e.g. parts of Iran, India, Brazil andsouthern France). However, this is not accurate.
Although maximum background radiation levels ofalmost 30 μSv/h have been reported for Ramsar, Iran,most other “hot” regions are considerably lower (e.g.
4.0 μSv/h in Kerala, India)[27,28]. Radiation levels
inside the Chernobyl and Fukushima zones have vast
areas greatly exceeding these levels [13,16,23]. In
addition, a recent meta-analysis of studies of thesenaturally radioactive regions provides compelling
evidence that these low levels are associated withdeleterious effects for their plant and animal
inhabitants [28]. Also, it has long been known thatnaturally occurring radon is the second leading causeof lung cancer in the US [29].
There have been many reports, mostly in thepopular media, that the Chernobyl Zone is filled withanimals as a consequence of reduced humanpopulation sizes, and this has by extension been used
to suggest that humans have larger effects on
biological conservation than do the effects ofradiation even at the site of the world’s largest
nuclear catastrophe. This allegory, however, is notsupported by any weight of evidence and its origin
was largely anecdotal and can be traced back to aletter to an editor by two observers who weresurprised to see physical evidence for more animals
inside the zone than they had seen on the outside (theletter is available upon request from the authors).
After all, almost everyone is surprised to see any
signs of life at all in the highly contaminated regionsof the Chernobyl Zone. Indeed, it is perhaps
surprising that as many animals as are seen continue
to be found in these areas. However, all of therigorously conducted studies of abundance andbiodiversity suggest that there are very significant

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Environmental Sciences: General

dose-related negative impacts on all groups ofanimals studied to date (although there is significant
heterogeneity among species in their responses), andthat many species are likely only sustained via
immigration from outside the zone. This is a matterof fact, not opinion.
To conclude, despite all that we have learned
from these recent studies of animal populations living
in Chernobyl and Fukushima [30], too little is known
concerning the mechanisms underlying effects in thetwo regions and this very clearly underlines theurgent need for significant and sustained investments
in research concerning the biological consequencesof acute and chronic exposure to radioactive
contaminants in the environment. Such research will
not only be relevant for the wildlife inhabiting theseregions but also for the large human populations
living in contaminated areas of these countries.
Given unlimited funding, we would propose asustained biological monitoring program of theecology, genetics, physiology and evolution of theorganisms living in Fukushima and Chernobyl. It isonly through such research that policy makers andsociety as a whole can judge the financial, health andenvironmental risks and hazards of nuclear accidents.
Clearly, recent developments in our broader
understanding of the biological consequences ofnuclear accidents point to many previously ignored or
misunderstood costs that have not been a part ofearlier discussions. Such shortcomings can easily be
addressed through a sustained research effort.

ACKNOWLEDGEMENTS
The authors thank our colleagues in Ukraine,
Belarus and Japan for help in the field, and theSamuel Freeman Charitable Trust, CNRS, QIAGEN
GmbH, the Fulbright Program, NATO, NSF, theNational Geographic Society, CRDF, and the
University of South Carolina for financial support
related to the research reported here.

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