It began in July 2011. Indigenous hunters in Alaska’s Arctic noticed ice seals they rely on for food and other uses covered in oozing sores and losing hair. They were sick and some were dying. Ultimately, more than 200 ice seals turned up with similar symptoms, prompting the federal government to declare the phenomena an “unexplained mortality event,” thus opening up research funding and attracting science minds to try to solve the mystery.

As of this month, despite the international group of scientists and researchers the declaration pulled together, no cause has been officially identified for the illness plaguing the ice seals.

In the time since the first sick seal was discovered, walruses and polar bears have turned up with similar ailments. The smallest of the species — seals — has fared the worst. Polar bears seemed to weather their sickness the best, with no fatalities connected to the illness and no clear clues about whether walruses and polar bears were afflicted with the same disease that had struck the seals.Curiously, the symptoms seem to have diminished since the first sightings of sick seals and other animals began in mid-2011. And Bruce Wright, a scientist with the Aleutian Pribilof Islands Association, thinks he knows why.“I suspected right from the beginning it was UV radiation,” Wright said in an interview from his Anchorage-based office this week. “I was expecting there would be consequences for an ozone hole that had formed over the Arctic.”Between March and April 2011, the National Oceanic and Atmospheric Administration (NOAA) documented “unprecedented chemical ozone losses” in the Arctic. Less ozone means more of the sun’s harmful ultraviolet rays reach Earth. Perhaps counter intuitively amid an era of climate change, it was cold temperatures in 2011 that lead to the UV increase. As NOAA explains, cold temperatures in the stratosphere allow polar stratospheric clouds to form, which create a good surface for chemical reactions to occur, namely the creation of chlorine, a gaseous agent capable of rapid ozone depletion.Wright isn’t suggesting all symptoms uncovered during necropsies of the affected seals are sun-burned related. Some of the animals were found to also have bleeding and swelling in their lungs, livers, lymph nodes and other internal organs. Scientists contemplated whether this was the result of secondary bacterial or fungal infections or depleted immune systems. Still, Wright questions the inter-relatedness of multiple stressors, including sun and UV radiation exposure, and other illness or nutritional deficiencies on the overall health of the animals.

He plans to present his theory in May at a science conference in Russia. “It all just made sense to me. I have just been baffled that nobody else has proposed this (sunburn) hypothesis,” he said.When told about Wright’s theory, Kathy Burek-Huntington, an Eagle River veterinarian who’s assisting with the federal study of sick seals, said, “I think that that’s pretty unlikely.”If sunburn were the culprit, she’d expect a more straight-forward pattern to the injuries, such as burns or lesions on the top of the head or the back — areas where seals would be most likely to get sun exposure.Still, the team of scientists Burek-Huntington is assisting has been looking into whether something called photo-sensitization is an aspect of the mystery illness. They wonder whether some other illness in the body is producing light-sensitive blood chemicals, similar to what can happen with hepatitis.Some skin injury patterns detected on seals support this theory, with lesions consistently found on the eyes, mouth and flippers. Yet, severe hepatitis hasn’t been found in the sick seals. And so the mystery deepens.One theory? A large algal bloom started in 2009 and which has continued every summer since in the Kotzebue Sound / Chukchi Sea is also being investigated as a factor. Could the bloom cause some chemical reaction in the Arctic animals that in turn has creates photo-sensitivity? Possibly.

“We don’t have a complete answer yet,” said Burek-Huntington, conceding that while many causal agents have been ruled out, there’s much work yet to be done.Preliminary tests to determine whether exposure from the 2011 Fukushima nuclear plant accident in Japan have also not revealed any answers. More tests on tissue samples for radionuclides associated with the event are being conducted, but those done so far have not yielded any direct connection.

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