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#ChernobylFrogs16 Chernobyl Recap: the Science

I am finally back from #ChernobylFrogs16 fieldwork at Chernobyl Exclusion Zone, so it is time for some recapitulation about the work I did there. As I mentioned in previous posts, the objective was to sample European treefrogs (Hyla arborea) on localities within Chernobyl Exclusion Zone, exposed to different levels of radioactive contamination originated by the accident of reactor number 4 of the Chernobyl Nuclear Power Plant in 1986.

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We chose this particular species because it’s highly terrestrial, living on bushes and grasslands during big part of the year, and those are areas more severely contaminated by radiation than water itself (Cesium does not stay much time dissolved in water and tends to aggregate with particles, sedimenting or getting absorbed by soil and vegetation). Our goal was to look at a wide range of genetic, physiological and developmental traits on these frogs to examine how chronic exposure to radioactive contamination could affect them.

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After four nights of work in the area, we collected a total of 84 male treefrogs in 6 different localities ranging from high contaminated places (ca. 30 microSv/h), to areas not contaminated at all. From these frogs we look first for morphological anomalies, such as presence of tumors or cataracts (reported for some birds in the area), extracted blood for physiological analyses, sampled a different array of tissues (liver and muscles) for epigenetic studies, collected skin microbiome and sperm samples, bones for skeletochronology (in order to estimate changes in lifespan associated with radioactive contamination), and preserved the frogs for estimating individual radioactive doses accumulated by each frog. All these procedures took about 15-20 minutes per individual, quite time-consuming, but would represent an extremely detailed multidisciplinary approach to understand how living in radioactive areas affects wildlife.

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This study is part of a much larger public funded EU-project aimed at improving and integrating research on the impact of radiation on man and the human food chain and on environment, particularly the protection of wildlife. This COMET project (COordination and iMplementation of a pan-Europe instrumenT for radioecology) represents a joint force of more than 20 institutions from 15 different countries. In particular, the study of the effect of radiation in amphibian biology implies researchers from the French Institute for Radiological Protection and Nuclear Safety (IRSN), the Chornobyl Centre (Ukraine), Doñana Biological Station (Spain), and the Swedish Universities of Stockholm and Uppsala.

Some of the samples are here with me in Uppsala ready to be analyzed (sperm, blood, histological samples), but most of them (the frozen ones) still need to get out of the Ukrainian custom bureaucracy in order to reach our labs.

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We already have some very preliminary indications that suggest than male treefrogs from the more contaminated locality (collected ca. 1.5 km from Chernobyl reactor 4) may be affected by living under such high radiations levels, although it is still too early to say something about (we first need to know the dose absorbed by each individual in order to have more solid interpretations).

It was an exciting time there in Chernobyl, but now starts the equally exciting time of getting data from these samples and perform all the analyses in order to understand how these frogs are affected by the different levels of radiation in the area. With the experience accumulated this year, I hope to be back in the area next spring to extend our sampling to more localities and more specific traits. On the meantime, at the end of August, I will be back in Ukraine for the COMET workshop “Thirty years after the Chernobyl accident what do we know about the effects of radiation on the environment?” Time to put research pieces together, and try to produce some general ideas about the long term effects of radiation in natural environments. Exciting time!!

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