Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 32, Number 8;   August, 2005

Sunburnt Frogs a Myth: Pond Scum offers Natural Sunscreen

TORONTO, June 30, 2004 -- Being green has become a little bit easier thanks to the research of York Biology. Licht, who has been studying the potential effects of ultraviolet radiation (UVB) on the biology of amphibians, says that, contrary to widespread belief and environmental reports, natural ambient UVB is unlikely to actually damage amphibians and plays little if any role in their global decline.

"This hypothesis of UVB killing amphibians has been widely circulated in the media," says Licht, who has been studying the ecology, evolution, and behaviour of amphibians and reptiles for more than 35 years. "Although widely debated, this UVB hypothesis has become deeply entrenched in the public and scientific views of environmental alarmist scenarios. My research and published work, on the contrary, has shown that the UVB hypothesis has little merit"

Licht says that amphibians possess natural defences against damage from exposure to UVB. To date, his research has shown: 1) that amphibian eggs/embryos have melanin pigmentation which absorbs most UVB; 2) the jelly covering around eggs reduces the amount of UVB reaching embryos; 3) amphibians possess an enzyme which repairs DNA damaged by UVB; and 4) amphibian eggs are normally deposited in water of lakes and ponds at depths of several centimetres, and this water usually contains dissolved organic content (murky pond scum) which is very effective at absorbing UVB and reducing the amount that extends downward.

"Thus, except in the clearest of lake water, most UVB is attenuated within the first few centimetres of water, and amphibians (frogs, toads, salamanders) normally lay eggs deeper than a few centimetres," explains Licht.

Licht's findings, "Shedding light on ultraviolet radiation and amphibian embryos", were published in BioScience, a leading North American journal that covers biological research. He maintains a Website on his research at http://www.yorku.ca/lel.

For more information or to arrange an interview, media should contact: Ken Turriff, York University Media Relations, 416-736-2100, ext. 22086 kturriff@yorku.ca.