Blaustein et al. reported that ultraviolet (UV-B) radiation caused deformities in salamanders (species Ambystoma macrodactylum. This result was based on an experiment where some salamander eggs were exposed to UV-B (at 90 percent of ambient levels) and other eggs were shielded from UV-B (about 94 percent).
Eggs that were shielded from UV-B were reported to have higher hatching rates and fewer deformities. The researchers concluded: "Our results suggest that there is potential for UV-B to cause deformities in other species and in other ecosystems that could ultimately be manifest at the population level. Thus, continued embryo mortality and an increasing frequency of deformities in amphibians may lead to population declines that are evident in many amphibian species."
But:
- Deformities in amphibians have been reported for at least 200 years. They're not new.
- These salamanders typically lay their eggs under rocks or in otherwise shady parts of ponds. So, unlike in the study, salamander eggs are typically not exposed to ambient UV-B. Moreover, the eggs exposed to ambient UV-B had a low survival rate (14.5 percent vs. 95 percent for the shielded eggs) and high deformity rate (92 percent vs. 0.5 percent for the shielded eggs). If salamander eggs were exposed to ambient UV-B and faired so poorly, the salamanders would have become extinct long ago.
- New research indicates that the deformities may be caused by a parasite. Click here for more information.
- Deformities linked with UV-B tend to be symmetrical. The deformities observed in the wild are asymmetrical.
Having already failed to link these defects to manmade chemicals in the environment, this genre of research now aims to implicate manmade ozone depletion as responsible for the deformities.
Better luck next time!
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