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30 years ago, during the early hours of the 26th April 1986, the reactor number 4 at the Chernobyl nuclear power plant in the North of Ukraine (then part of the USSR) suffered a thermal destruction and exploded during a technical test, causing the largest accidental release of radioactive material into the environment as a consequence of human activity. After the initial release of radiation, the liberation of radionuclides to the environment continued for ten more days. Radioactive material was deposited over vast areas of Ukraine, Belarus and Russia, but fallout also happened all across Northern and Central Europe, Scandinavia and Austria in particular, due the predominant winds and rain patterns of the days following the reactor explosion.


Photos from Flickr by Timm Suess and Trey Ratcliff

After the accident, an Exclusion Zone of 30km was created around the nuclear plant and the vast majority of the population was moved out (e.g. the entire city of Pripyat, ca. 50.000 people living at 3km of the reactor, was evacuated after the explosion). This area has remained virtually unoccupied by humans and controlled by the Army since then.

On the 8th May 2016 I will be flying to Chernobyl, to conduct field work in the Exclusion Zone (also known as Alienation Zone) during a week.

But, Why I am going to Chernobyl?

The immediate impact of the release of vast amounts of radioactive products to humans to the environment is clear 1,2. However, the long-term effects of the chronic exposure to low-dose radiation after these accidents are still matter of debate. Studies conducted in the Chernobyl area have frequently detected detrimental effects of radiation in wildlife, ranging from population declines and reduction in bird survival, to an increase in the frequency of albinism, tumors and other physiological and developmental anomalies 2-4. However, 30 years have passed since the Chernobyl accident, and more recent studies have started to suggest patterns of adaptation to the chronic exposure to low-dose radiation levels in wildlife. Abundance of large mammals has increased in the zone over the last years 5, birds seem to have developed adaptation to oxidative stress 6, and feather-associated bacteria seem resistant to ionizing radiation 7. Many studies have also been conducted in birds or mammals that move over much larger distances and can even perform transcontinental migrations, living outside the Zone for most part of the year. Furthermore, some of the studies indicating severe effects of radiation in wildlife have faced strong methodological criticism 8.

It is clear that more carefully planned studies covering a wider diversity of organisms and ecosystems, are needed to better evaluate the consequences of chronic exposure to low-dose radiation in wildlife. This task is even more relevant since the accident occurred in the Japanese Fukushima-Daiichi nuclear power plant as a consequence of the tsunami that hit the area in March 2011. Understanding the effects of low-dose radiation in animals and plants may be a crucial step to develop accurate strategies to manage contaminated areas, and to determine their suitability for future human activity.

And that’s essentially why I am going to Chernobyl… During my trip to the Chernobyl area, I will try to evaluate the impact of chronic exposure to radiation in the genetics, physiology and development of amphibians by sampling European treefrogs (Hyla arborea) living in areas with different concentration of radioactive material. My plan is to examine a full range of traits, from morphological anomalies to epigenetic changes, in collaboration with researchers from the Chornobyl Centre-Ukraine, the Stockholm University-Sweden, the Institute for Radiological Protection and Nuclear Safety-France and the Doñana Biological Station-Spain.

European Tree Frog (Hyla arborea). Photo from Flickr by Frank Vassen 

Amphibians are great study models for examining the impact of chronic low-dose radiation in animals, since they occupy both the aquatic environment (as larvae and during the breeding period) and the terrestrial environment (as juveniles and as post-reproductive adults), so they are exposed to radiation present both in water and soil. Moreover, due their high philopatry and low dispersal capacities they tend to move over small-size territories, making easier to link environmental levels of radiation with differences in biological traits.

Now, is time for me to finish with the planning and sampling preparations, marking and sorting all kind of vials, arranging the transport of frozen samples from Ukraine to France and Sweden. It’s time also for my Ukrainian colleagues to request and collect all type of permits for conducting our work there. And, of course, time to hope for the frogs to be there, actively calling at the breeding localities. Let’s see…

(I will post more about my work with the frogs of Chernobyl here, and on Twitter via @GOrizaola and #ChernobylFrogs16)

1. Geras’kin et al. 2008. Environment International 34, 880-887.
2. Beresford and Copplestone 2011. Integrated Environmental Assessment and Management 7, 371-373.
3. Møller and Mousseau 2006. Trends in Ecology and Evolution 21, 200-207.
4. Beresford et al. 2016. Journal of Environmental Radioactivity 157, 77-89.
5. Deryabina et al. 2015. Current Biology 25, R811-R826.
6. Galván et al. 2014. Functional Ecology 28, 1387-1403.
7. Ruiz-González et al. 2016. Scientific Reports 6, 22969.
8. Smith 2008. Biology Letters 4, 63-64.