They recreated the Chernobyl accident to study the effects of radiation

They recreated the Chernobyl accident to study the effects of radiation on biodiversity.

The objective of the work in which the Doñana Biological Station participates is to verify if melanin is a protective factor against radiation and if there are patterns of adaptation to radiation.

On April 26, 1986, the fourth reactor at the Chernobyl nuclear power plant accidentally exploded, causing the largest leak of reactive materials in history. 38 years later, the Chernobyl region has become a surprising natural laboratory to study the effects of radiation on fauna and flora as well as to study how species recolonize areas abandoned by man.

A research team from the University of Oviedo and the Doñana Biological Station has been working in this direction for eight years. Today, when the war prevents them from returning to Chernobyl to continue their research, scientists have begun a series of experiments to recreate the Chernobyl accident and study how radiation affects amphibians and beetles.

"Amphibians are good models for this type of research. They are exposed to both aquatic and terrestrial environments and move little, so their exposure to radiation is usually more stable."explains Pablo Burraco, researcher at the Doñana Biological Station (CSIC). The scientist together with researcher Iván Gómez-Mester carried out the first experiment in the laboratory of their research center located on the island of Cartuja in Seville.

The goal was to simulate a nuclear accident to test whether melanin was a protective factor against radiation, as had been suggested in observational studies carried out at Chernobyl before the nuclear accident.

The pandemic temporarily halted their projects. In 2016, researcher Germán Orizaola from the University of Oviedo began research to determine the effects of radioactivity on tree frogs (Hyla Orientalis). The following year he would be joined by researcher Pablo Burraco.

After three years of careful sampling at Chernobyl, the results seemed to indicate that the radiation had little effect on frogs, except for one thing: its color. Specimens that live in the Exclusion Zone, a disaster evacuation zone, have a darker tone than those that live outside of it. Some are even completely black, unlike the bright vere color that this species usually exhibits.

"The results show that melanin protects them from the ionizing radiation of a nuclear accident, in a similar way to how it protects us from ultraviolet radiation.”explains Germán Orizaola. Natural selection must have acted ruthlessly after the nuclear explosion, making darker-colored frogs more likely to survive than greener frogs.

Recreate a nuclear accident

That study was purely observational in nature. They found a correlation that suggested, but did not prove, that melanin was a protective factor. To corroborate this, it was decided to recreate the nuclear accident under controlled conditions, which can be carried out in laboratories far from the Chernobyl accident area, strictly respecting European regulations.

The first thing that researcher Burraco did at the beginning of the experiment was to place larvae from the same spadefoot toad colony (Cultripes), very common in Doñana, in black and white cubes. It is known that, like many other amphibians and reptiles, the larvae of this species have great plasticity and can change the color of their skin depending on the environment. This would make some frogs darker and others lighter.

In collaboration with the National Accelerator Center, the larvae were exposed to various levels of radiation for short periods of time. "The doses are not fatal, so at first, we could not find the difference in death rate related to color"explained Pablo Burrako. The experiment took place for more than a year and during this time, the frogs were still in climatic chambers in very controlled conditions to avoid the incidence of other factors.

"At the moment they look very good and there are practically no differences in size, but something is starting to happen inside them. We are starting to see differences in mortality”said the researcher. We will have to wait a few more months to obtain the definitive results.

Recently, the research team began another experiment in a similar direction, this time with frogs of the genus Xenopus. The experiment was carried out at the University of Stirling in Scotland with funding for the Nuclear Safety Council.

Charnobyl accident

In this case, the radiation exposure is lower, but over a longer period of time and simulating different radiation slopes currently existing after the Chernobyl accident. “With this experiment we wanted to see what would happen if the frogs were exposed to radiation throughout their embryonic development.”explains Burraco.

Researchers will study the effects of radiation on the survival, physiology and morphology of the frogs. During these weeks, the team carried out tests to begin a third experiment, this time with beetles.

They will also do it at the Doñana Biological Station in collaboration with Francisco García's research group and again the National Accelerator Center. One of the challenges that vertebrates pose for this type of research is that their reproductive cycles are usually very long. Beetles, on the other hand, have a new generation every 20 days.

Beetles said: “By working with beetles we will be able to see if there are transgenerational effects and patterns of adaptation to radiation exposure and thus see the evolution in real time."

Chernobyl accident, 38 years later

"Chernobyl is not what is shown in the documents”says Germán Orizaola. "It has become a spectacular refuge for wildlife"After the nuclear accident, an Exclusion Zone was created around the Chernobyl plant with an area of ​​4.700 square kilometers which, after several decades of almost no human presence, became a critical point of biological diversity, inhabited by wolves. , bears and lynxes, and even wild horses like the Przewalski's horse that can roam freely.

"We have national parks like Doñana or Picos de Europa that we should leave only for conservation. There is no need to ride excursions or roads”says Orizaola. The explosion of the Chernobyl nuclear power plant became one of the most dangerous disasters in human history.

38 years later, as radiation levels decreased, the Chernobyl accident zone became the ideal natural laboratory to learn what happens when humans leave the area. According to the researcher, sometimes the best way to protect nature is simply not to disturb it.

With information of: Doñana Biological Station