Australia’s Great Barrier Reef Threatened
Australia's National Coral Bleaching Task force says the country's Great Barrier Reef is facing the "worst mass bleaching event in its history."
The reef is a United Nations Educational Scientific and Cultural Organization World Heritage site. It has more than 400 species of coral and 1,500 kinds of fish. It is the only reef that is a Heritage site, a place that is named by UNESCO as having special cultural or physical significance.
The reef is along the northeastern coast of Australia. It is three quarters the size of the western American state of California.
Bleaching happens when sea temperatures rise. Higher temperatures cause the coral to force out colorful algae. The coral becomes white.
If the water temperature falls, the process could reverse. Algae could return to the coral. If it does not, the coral could die.
Researchers examined aerial surveys of more than 500 reefs north of the city of Cairns. The researchers said most of the reefs suffered from severe bleaching.
Terry Hughes leads the National Coral Bleaching Task force.
He said "this has been the saddest research trip of my life."
"We flew for 4,000 kilometers in the most pristine parts of the Great Barrier Reef and saw only four reefs that had no bleaching. The severity is much greater than in earlier bleaching events in 2002 or 1998," he said.
Hughes also said "it's still too early to tell just what the overall outcome will be. We will continue to conduct underwater surveys along the Great Barrier Reef in the coming months as the full impact of this mass bleaching event unfolds."
Hughes said the most of the severe bleaching was in the northern part of the reef. He says the southern part was not as affected because of "cloudy weather that cooled the water temperatures."
He said the bleaching was likely made worse by the strong El Nino event in the Pacific Ocean. The Washington Post reports there have been three recorded mass bleaching events -- in 1998, 2010 and this year. All three took place at the same time as the El Nino event.
I'm Ashley Thompson.
1.three quarters of 四分之三
The sea is very big. It covers three quarters of the globe.
2.sea temperatures 海洋温度
They believe that rising sea temperatures are driving the decline.
3.took place 发生
Notwithstanding his objections the marriage took place.
4.at the same time 同时
He was at the same time haughty, reserved, and fastidious.
1.Algae could return to the coral. If it does not, the coral could die.
return to 返回；恢复
I shall return to this point later.
Let's now return to that situation for a somewhat closer look at things.
2.The researchers said most of the reefs suffered from severe bleaching.
suffered from 遭受；患有
The operation was successfully performed, but the patient suffered from shock.
I merely told him that I suffered from nightmares.
海水温度上升就会发生珊瑚白化的现象 。温度越高会导致珊瑚释放更多彩色海藻，从而使珊瑚变白 。
水温下降，这一情况会慢慢好转 。海藻也会重新回到珊瑚中间 。若温度持续走高，最终珊瑚可能会死亡 。
研究人员对凯恩斯市北部500多个珊瑚礁进行航拍 。研究人员称，大多数珊瑚礁发生了严重白化的现象 。
特里·休斯（Terry Hughes）是澳大利亚国家珊瑚白化工作组的负责人 。
他说，“我们沿着大堡礁最原始的地区飞行了4000千多公里，唯有四处珊瑚礁没有白化 。这程度比2002年或1998年的早期白化事件要严重得多 。”
休斯还表示，“现在下结论还为时过早 。这一大规模白化现象的影响不断扩散，未来数月我们将继续沿大堡礁进行水下作业 。”
休斯表示，白化最严重的地区是北部的珊瑚礁 。他说，南部的珊瑚礁因多云天气水温下降，因此并未受到严重影响 。
他还强调，太平洋地区的厄尔尼诺现象可能会让白化现象更加严重 。《华盛顿邮报》报道称历史上共发生了三次大规模珊瑚白化事件，分别在1998年、2010年和今年 。三次白化事件发生的时间都与厄尔尼诺现象的时间吻合 。