Wednesday, 15th August 2007, 00:03
The ecological effects of the Chernobyl disaster on animals are considerably greater than feared, a study suggests.
Recent conclusions from the UN Chernobyl Forum and media reports concerning the effects of radiation from the nuclear power plant has left the impression that the Chernobyl Exclusion Zone is a thriving ecosystem filled with an increasing number of rare species.
But surveys of breeding birds at forests around the site found the abundance of species decreased with rising level of radiation.
Professor Anders Moller and colleagues at the University of South Carolina recorded 1,570 birds representing 57 species and found their numbers were reduced by more than half when comparing areas with the highest amount of radiation with those that had the normal background level.
They suggest radiation could directly reduce survival rates and fecundity causing extinction or reducing population sizes as shown previously for the barn swallow Hirundo rustica.
Secondly birds may avoid radioactively contaminated areas because such areas are not good habitats for birds.
Otherwise birds could be fewer in contaminated areas owing to less insects that constitute the most common food source.
Prof Moller said: “We have previously demonstrated significant negative impacts of Chernobyl-related fallout on barn swallow mutation rates, survival and reproduction.
“Here we extend our observations to document extensive reductions in the species richness, abundance and
population density of birds in general with increasing levels of radiation around Chernobyl.
“These effects are likely to have important implications for other parts of the ecosystem and for overall ecosystem functioning.”
The study, published online by the Royal Society in Biology Letters, said the effects of low-level radiation on the abundance of animals are poorly known – as are the effects on ecosystems and their functioning.
Prof Moller said: “Surprisingly there are no standardized censuses of common animals in relation to radiation leaving the question about the ecological effects of radiation unresolved.
“These results imply that the ecological effects of Chernobyl on animals are considerably greater than previously assumed.”
A UN report estimated about 9,000 people exposed to radiation in the Chernobyl incident in 1986 would die from cancer. But Greenpeace has said has said the number of deaths linked to the incident could be closer to 90,000