鲸鱼被晒伤或为臭氧层空洞所致

It's not just holidaymakers who need to keep covered up in the sun.

Scientists have discovered that a growing number of whales are suffering from sunburn - and that the hole in the ozone layer could be to blame.

The findings come from a study of 156 blue, fin and sperm whales swimming in the Gulf of California.

Researchers have long known that whales suffer blisters on their backs. However the reason why they have lesions has been a mystery - until now.

After analysing the sores on high resolution photographs and studying whale skin samples in the laboratory, a team of British and Mexican researchers now believe they are caused by acute sunburn.

Dr Laura Martinez–Levasseur, of the Zoological Society of London, said: 'Whales need to come to the surface to breathe air, to socialise and to feed their young, meaning that they are frequently exposed to the full force of the sun.'

Blue whales, who have fairer skin than most whales, suffered more than the darker fin whales, she reports in the journal Proceedings of the Royal Society B.

Sperm whales, which spend more time than other species at the surface, were also vulnerable.

The increase in sunburn appears to be worst for blue whales, the study found. In 2007, just six out of 48 blue whales had sunburn. By 2009, 15 out of 22 whales studied were suffering.

'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,' Dr Martinez-Levasseur said.

'A likely candidate is rising ultraviolet radiation as a result of either ozone depletion, or a change in the level of cloud cover.'

Her co-author Professor Edel O'Toole, from Queen Mary, said: “As we would expect to see in humans, the whale species that spent more ‘time in the sun’ suffered greater sun damage.

'We predict that whales will experience more severe sun damage if ultraviolet radiation continues to increase.”

The researchers are unsure whether the lesions are painful - and whether sunburn increases the risk of skin cancer in whales.

One reason for the rise in sunburn could be the hole in the ozone layer - the protective layer that shields the Earth from the sun's harmful ultraviolet rays.

Since the 1970s, scientists have known that the protective layer is being depleted by manmade gases, in particularly the CFCs once used in aerosols.

Although CFCs have been banned, the ozone layer is still being depleted from gases released many years ago, and holes exist above both poles.

并不是只有外出度假的人才需要防晒。

科学家发现，越来越多的鲸鱼被晒伤，而臭氧层空洞则可能是幕后元凶。

这些发现是在对加利福尼亚湾的156只蓝鲸、长须鲸和抹香鲸进行研究后得出的。

研究者在很久以前就知道鲸鱼的后背上会起水疱。但是直到现在，造成这些皮肤伤的原因依然是个谜。

一个由英国和墨西哥研究人员组成的研究团队对高分辨率照片上的鲸鱼水疱进行了分析，并在实验室里对鲸鱼的皮肤样本进行了研究，他们现在认为这些水疱是由严重的晒伤导致的。

伦敦动物学会的劳拉•马丁内斯-勒瓦瑟博士说：“鲸鱼需要到水面上来呼吸空气、进行社交和哺育幼儿，这意味着它们会频繁地暴露在阳光的强力照射之下。”

她在英国皇家学会生物研究期刊上的报告中写道，蓝鲸的皮肤颜色比大多数鲸鱼都浅，因而晒伤也比皮肤颜色深的长须鲸更厉害。

抹香鲸待在水面上的时间比其他种类的鲸鱼都要长，所以也很容易被晒伤。

研究发现，被晒伤的鲸鱼越来越多，而蓝鲸在这方面情况似乎是最糟的。2007年，48只蓝鲸中只有6只被晒伤。到了2009年，作为研究对象的22只蓝鲸中就有15只被晒伤。

马丁内斯-勒瓦瑟博士说：“蓝鲸皮肤伤的增多令人担忧，但在目前这个阶段还不清楚是什么原因导致了晒伤的增多。”

“一个可能的原因是臭氧耗竭或云层高度改变引起紫外线辐射增强。”

和她一起合著这一报告的来自伦敦大学玛丽皇后学院的艾德尔•奥图尔说：“正如我们会在人类身上看到的一样，‘在太阳下的时间’更多的鲸鱼也会遭受更严重的晒伤。

“如果紫外线辐射继续加强的话，我们预计鲸鱼将遭受更严重的晒伤。”

研究人员不确定这些水疱是否会疼痛，也不确定晒伤是否会增加鲸鱼患皮肤癌的风险。

晒伤增多的一个原因可能是臭氧层空洞，而臭氧层是保护地球不受太阳紫外线危害的保护层。

自从20世纪70年代以来，科学家就知道这一保护层一直被人造气体损耗，特别是曾用于喷雾剂的氯氟烃。

尽管氯氟烃已经被禁用，但是由于多年前排出的气体，臭氧层仍然继续被损耗，目前在地球两极上方都有臭氧层空洞。

Vocabulary:

lesion: damage to the skin or part of the body caused by injury or by illness （因伤病导致皮肤或器官的）损伤，损害

Royal Society B: 这里的B指的是biological sciences

CFC: 全写为chlorofluorocarbon，氯氟烃

aerosol: a substance enclosed under pressure and able to be released as a fine spray, typically by means of a propellant gas（喷雾剂）