GLOBE & MAIL (Toronto, Ontario) 01 June 04 Decline in amphibians linked to sunburn (Mary Nersessian)
The global decline of amphibians, which do not have the luxury of slathering on sun block, is partly linked to sunburn, researchers suggest.
Ultraviolet radiation is one of several components that cause damage to amphibians at every stage of their life cycle, Oregon State University zoology professor Andrew Blaustein told globeandmail.com on Tuesday.
Mr. Blaustein, the lead author of the study, said the erosion of the ozone layer has contributed to the decline of amphibians – frogs, toads and salamanders – around the world.
“Every species you look at that has been exposed to ultraviolet rays has some kind of damage,” he said.
Researchers said other factors contributing to the global amphibian decline include habitat destruction, global climate change, introduction of exotic species and parasites, but UVB radiation is high on the list.
All amphibians exposed to natural levels of UVB rays are threatened as a result of a weakened immune system, deformity, and life-threatening illnesses, both as larvae and adults, the study reports.
Mr. Blaustein explains that UVB rays affect amphibians much like they do any plant, animal, or human – they damage the skin, causing a cell's death or mutation.
Unlike humans, amphibians can die almost immediately if their eggs are exposed to the radiation, or they can develop retinal damage and blindness as adults.
Other researchers theorized that amphibians could avoid radiation by keeping out of the sun or laying eggs in deeper water levels.
This theory, however, ignores “millions of years of evolution” in which amphibians learned to lay eggs in warm, shallow waters for heat and sunlight so that they can hatch before the water freezes or evaporates, Mr. Blaustein said.
He said it has become increasingly difficult for amphibians to seek shade as ponds dry out and water levels decrease.
The study reports that 60 species of frogs, toads, and salamanders in 46 states and across four continents have been found with deformed legs and eye damage.
Decline in amphibians linked to sunburn