A three-year study of endangered and vulnerable whales in the Gulf of California, published in the Proceedings of the Royal Society B, found the mammals suffering from lesions and dead cells caused by ultraviolet rays from the sun.
“This is the first evidence that the Sun’s rays can cause skin lesions in whales,” said Laura Martinez-Levasseur of the Zoological Society of London and doctoral student at the University of London. “The increase in skin damage seen in blue whales is a matter of concern, but at this stage it is not clear what is causing this increase. A likely candidate is rising ultraviolet radiation as a result of either ozone depletion, or a change in the level of cloud cover.”
Ozone in the earth’s stratosphere has declined steadily by about 4 percent each decade since the 1970s causing a larger hole over the polar regions. Emissions of chemicals, CFCs, known as man-made ozone-depleting-substances have now been regulated but the recovery of the layer of ozone around the earth that buffers UV exposure is under debate.
Skin samples and high resolution photos of more than 150 fin, sperm and blue whales were gathered by Martinez-Lavasseur, her colleagues and scientists from Mexico’s Interdisciplinary Marine Science Center showed blistering, lesions and dead cells associated with damage from the radiation of the sun. Damaged cells were also found on the lowest layer of skin, meaning the whales were suffering from severe burns.
The skin symptoms worsened during the study, with the lighter skinned blue whales most susceptible to burns. The darker pigments of the sperm and fin whales produce more melanin and leaving them less vulnerable to the sun’s rays.
Martinez-Levasseur said the whales serve as a model for marine animals because “they need to come to the surface to breathe air, to socialize and to feed their young, meaning that they are frequently exposed to the full force of the sun.”
She also pointed out that unlike us, whales are more vulnerable to the sun’s damage since they can’t cover themselves with protective clothing before going out into the sun.
The sun’s rays are added stress to the whale’s survival. All the species studied in Mexico’s Gulf of California are listed as endangered or vulnerable by the International Union for Conservation of Nature.
The researchers will next study how the whale’s genetics adapt to the harsh rays and if they develop darker pigmentation as a result.