Sunburn could put the future of frogs at risk
image:
A tadpole of the common eastern Australian species, the striped marsh frog (Limnodynastes peronii).
view moreCredit: Dr Niclas Lundsgaard
Australian research has shown exposure to intense UV radiation for short periods causes catastrophic DNA damage in tadpoles, potentially contributing to the global decline of frog populations.
Aquatic ecologist Dr Niclas Lundsgaard said short bursts of exposure to high levels of ultraviolet B (UVB) – a recognised cause of sunburn in people – caused 50 per cent more damage to tadpoles than a lower level of UVB for a longer period.
“We found it was not just the total amount of UVB but also the intensity at which it was delivered that was overwhelming cell repair mechanisms leaving the tadpoles with residual DNA damage,” Dr Lundsgaard said.
“It’s the kind of damage that could impact their growth, ability to metamorphose into frogs or even kill them.
“This is an important finding as we work to understand the impacts environmental changes such as a warming climate and changes to cloud cover along with habitat loss are having on frog populations.”
The laboratory study at The University of Queensland’s School of the Environment compared 2 groups of tadpoles from a common eastern Australian species, the striped marsh frog (Limnodynastes peronii).
One group experienced short-duration exposure to UV light at midday intensity levels, while the other spent twice as long under lamps with half of the UV intensity.
Dr Lundsgaard said by the end of the exposure periods, each group had received the same total UVB radiation dose.
“The hypothesis traditionally has been that because the tadpoles were getting the same amount of radiation, the effects should also be the same,” he said
“But we saw that high intensity exposure was much more damaging.
“Molecular analysis revealed high intensity exposure caused DNA damage to accumulate 3 times faster, with more damage carrying over into the following day.
“We also found smaller tadpoles were the most sensitive and had more DNA damage.
“Knowing all of this for frogs raises questions for other animals and is an area for further research.”
The research paper is published in Journal of Experimental Biology.
Journal
Journal of Experimental Biology
Method of Research
Experimental study
Subject of Research
Animals
Article Title
When repair mechanisms fail to keep up: high UVB irradiance causes disproportionate accumulation of DNA lesions
Article Publication Date
2-Jul-2026
COI Statement
C.E.F. is the Editor in Chief of the Journal of Experimental Biology. C.E.F. was not involved in the editorial assessment of this submission. The authors declare no other competing interests.
Strong sunburn causes catastrophic DNA damage for tadpoles
Intense sunburn causes 47% more DNA damage for tadpoles in Australia with lethal consequences
Sunburn is a serious problem in the Southern Hemisphere where depleted ozone provides less protection from UVB. Tadpoles are at particular risk because they are growing rapidly, making them vulnerable to UVB DNA damage. Niclas Lundsgaard, of The University of Queensland (UQ), Australia says that the seriousness of sunburn was thought to be directly linked to the degree of exposure, so that a long weak dose of UVB would yield the same DNA damage as a short intense dose that resulted in the same overall exposure. But Lundsgaard, Craig Franklin and Rebecca Cramp (also from UQ), weren’t sure. A short intense UVB dose can be 3 times more lethal for striped marsh frog tadpoles (Limnodynastes peronii) than a long weak UVB dose amounting to the same overall exposure. The team publishes their discovery in Journal of Experimental Biology that sunburned tadpoles suffer significantly more DNA damage from short intense doses of UVB than longer weaker doses, which could dramatically increase mortality on sunny days.
Collecting recently laid frogspawn from a creek in Brisbane, Lundsgaard took them to the UV-free lab where they developed for 5 weeks. Then, he turned on the UVB, making sure that different tadpoles got the same total exposure of UVB, no matter how strong the dose, by adjusting how long the UV lights were on for.
Some tadpoles received one intense (80μW/cm2) dose of UVB – simulating the light levels in a clear pond – for an hour, while others received a second strong hour-long dose a day later. Meanwhile, he turned down the sun lamps for other tadpoles, so the UVB was less intense (40μW/cm2), but kept the lamps on for 2 h so the tadpoles received the same overall exposure, with a fourth group of tadpoles receiving a second weak dose of UVB a day later.
Finally, Lundsgaard checked for evidence of DNA damage.
Alarmingly, the strength of UVB that the developing tadpoles experienced had a dramatic impact.
The tadpoles that experienced the most intense doses of UVB accumulated damage almost 3 times faster, resulting in 47% more DNA damage than the tadpoles exposed to mild sunburn.
Lundsgaard then checked the tadpoles that were exposed to UVB on consecutive days, and the tadpoles that had experienced the strongest sunburn were in worse shape than the tadpoles that had only received mild UVB doses.
The intensely sunburned tadpoles carried over twice as much DNA damage into the second day, and the tadpoles that experienced 2 days of sunburn had 20% more DNA damage than the tadpoles that only experienced sunburn on a single day.
Surprisingly, Lundsgaard noticed that the smallest tadpoles seemed to suffer the most DNA damage, experiencing 50% more than their larger siblings, thanks possibly to their larger surface area relative to their mass.
Even though the striped marsh frog tadpoles had experienced the same amount of UVB, the strength of the sunburn made an enormous difference.
The tadpoles exposed to the high UVB dose accumulated more dangerous DNA damage than those that had received the same total UVB exposure over longer periods, leaving them at greater risk of mortality.
Lundsgaard warns also that fish and corals could be in similar danger from the sun’s rays. ‘The larvae of other aquatic animals might struggle with more frequent exposure to short, intense UVB’, he says.
However, Lundsgaard adds that we cannot draw any conclusions about whether stronger sunburn is more dangerous for people. ‘Frogs and humans have different mechanisms for repairing DNA damage caused by UV radiation’, he says, but adds, ‘Our study has highlighted that the risk of sun exposure is not necessarily measured simply by how much radiation you are exposed to’.
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REFERENCE: Lundsgaard, N. U., Franklin, C. E. and Cramp, R. L. (2026). When repair mechanisms fail to keep up: high UVB irradiance causes disproportionate accumulation of DNA lesions. J. Exp. Biol. 229, jeb252227. doi:10.1242/jeb.252227
DOI: 10.1242/jeb.252227
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Journal
Journal of Experimental Biology
Method of Research
Experimental study
Subject of Research
Animals
Article Title
When repair mechanisms fail to keep up: high UVB irradiance causes disproportionate accumulation of DNA lesions
Article Publication Date
2-Jul-2026
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