Ron Estall of Palmerston North asks :-
New Zealanders are reportedly exposed to about 40 per cent more cancer-causing sunrays than North Americans living at similar altitudes. What are the potential long-term effects of such exposure on plants and animal life?
Tim Brown, a microbiologist at Massey University, responded.
It is as well to note that that UV-B exposure at the poles is over a thousand times lower that at the equator. This shows from the outset that a wide range of UV-B intensities can be withstood by plants and animals and they have adapted to their particular environments.
Microbiologists have always used UV as a mutagen (I see the use of the term genotoxic being used now?) but this was in lab conditions. Most micro-organisms are well protected from the sun. Cyanobacteria, and other aquatics, may not be. Their exposure depends on the UV transmission through water. If the UV is too strong they just seem to be able to exist a little deeper.
UV-B can detroy DNA and interfere with photosynthesis but there is strong evidence of a range of protective and repair mechanisms. Flavenoids in apples and other pigments in plants are protective.
Animals would be most likely to suffer if their plant foods were knocked out of the food chain by UV-B. They can of course get skin cancer like humans but they do naturally choose shade if it is available.
The overall picture, in a very patchy scene, is one of organisms being able to withstand, protect and adapt. I think it would require a very rapid increase in the sunrays, and the attendant UV, to cause any major catastrophic effect in the flora and fauna, domestic or other wise.