VOA常速英语:珊瑚礁：气候变化的晴雨表

Here in the northern Red Sea in the Bay of Aqaba, Israeli scientists have discovered something extraordinary. Despite higher water temperatures, these corals are healthy and even thriving. We found that corals are not bleaching. We’ve never witnessed any bleaching event which is so common elsewhere. To find out why, small corals were subjected to bleaching conditions in the laboratory. Their ruddy color is a sign of good health. Bleaching conditions are usually considered as 1 to 2 degrees above the summer maximum and there was no bleaching. We elevated the the temperature furthermore and only at 5 and 6 degrees above some maximum, they showed signs of stress and bleaching.

But how can the coral here withstand such high temperatures when mass coral bleaching is occurring elsewhere? The answer may be found 18,000 years ago when the Red Sea was much hotter. In order to survive conditions, very hot conditions in the southern Red Sea, they had to be or undergo selection towards thermally resilient corals. Those that suffer from the hot, the very hot conditions down there didn’t survive, and so corals that we see here nowadays are the ones that are descendants of the ones that survived. The study also indicates that future generations of coral in the Bay of Aqaba will also be immune to bleaching. Think that although see what the temperature is rising in the Gulf of Aqaba, maybe at a rate that exceeds the global average, still we have about a hundred years before these corals will experience bleaching conditions or cross the bleaching threshold. Coral reefs are often the first indicator of climate change. Their loss would raise the risk of extinction of thousands of fish species and other marine life.
Deborah Block VOA News.