Chernobyl Worms Have Begun To Have Sex

The influence of radiation upon human beings has been thoroughly studied, while practically no investigation has been held concerning the effect it exerts upon nature

Worms inhabiting the radioactive zone near the nuclear power plant in the Ukrainian city of Chernobyl have begun reproducing by syngenesis and have ceased unisexual reproduction. Ukrainian scientists hypothesize that the changes in sexual behavior have taken place because they raise the chances of thee species to survive. The discovery was the first direct evidence proving that the radioactive contamination has affected natural fauna.

The influence of radiation upon humans has been thoroughly studied, while practically no investigation has been undertaken concerning the effect it has upon nature. The standards of radiation safety developed by the International Commission on Radiological Protection (ICRP) assume that, if safety measures are taken to protect human beings from radiation, then animals and plants would be protected as well.

However, recently, the Commission has given up this approach and initiated investigations aimed at determining optimal methods for wildlife protection. The majority of scientists working under the aegis of the commission are currently focused on the effect of radioactive contamination upon flora and fauna.

Ukrainian scientists Gennady Polikarpov and Viktoria Tsitsugina, from the Institute of Biology of the Southern Seas in the city of Sevastopol (Ukraine), studied reproduction of three species of worm inhabiting a lake situated in the area affected by the tragic blast at the Chernobyl nuclear power plant that took place in April 1986. To be able to draw a comparison, the scientists examined the reproductive process of worms living in a lake situated 20 kilometers from the Chernobyl nuclear power plant. The lakes have similar temperatures and chemical compositions. However, the radiation level in the lake closer to the nuclear power plant exceeds that determined in the remote lake by 20 times. Considerable changes were observed in the sexual behavior of worms living in the Chernobyl lake.

Both worm species have proceeded to syngenesis, the possibility of which is inherent in their biology. The percentage of Nais pardalis worms that have started syngenesis in the Chernobyl lake is 22 percent, while the figure comes to only 5 percent in the more-distant lake. In the case of the species Nais pseudobtusa, the corresponding percentages came to 23 percent and 10 percent. However, one more species, Dero obtuse, registered a double increase in unisexual reproduction in the contaminated lake.

Polikarpov believes that worms have started syngenesis because it protects them from radiation. This method of reproduction clears the way for natural selection, using which species are better adapted to survive radiation and transmit their genes on to their descendants. In this way, the Ukrainian scientist says, the resistance of the population as a whole increases.

ICRP expert Carmel Motersill at the Dublin Technology University supports this opinion. She says that such a mechanism is appropriate under the conditions of the lake and the area near the Chernobyl nuclear power plant.

New Scientist