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The white plague that kills the coral

The warming of the sea is killing corals, which suffer a devastating bleaching process.

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The newspapers keep a file of obituaries on illustrious characters written in advance to come to light when they are needed. In general, they are boring texts, full of data for which we should remember the deceased.

That is why few have managed to capture as much attention as that published by outside magazine in early October 2016: “The Great Barrier Reef of Australia died in 2016 after a long illness. It was 25 million years old. “Thus begins the obituary written by Rowan Jacobsen to honor the largest coral reef in the world.

Social networks burned in protests and lamentations. During the days following the publication, the experts in these wonderful underwater structures were harassed by the media in search of answers. Therefore, Terry Hughes, director of the Center for Excellence for Coral Reef Studies of the Australian Research Council, was forced to state categorically that “neither the coral reef has died, nor should we give it up for lost”. The scientists did not deny the difficult future facing corals, but they did not like sensationalism in the news. “It’s as if someone cut down half of a forest and said it has disappeared entirely,” complained Russell Brainard, director of the Coral Reef Ecosystem Program, at the Pacific Islands Fisheries Science Center of NOAA, the Administration National Oceanic and Atmospheric Survey.

Navigation, overfishing and pollution, which have damaged the ecosystem for decades, are nothing compared to the silent threat that corals face: the rise in water temperature, which has already killed immense areas of water reefs in recent years, even in remote areas of the human being.

Although corals , whose polyps – each of the multicellular organisms that make up a coral colony – are smaller than a grain of rice, filter the water and feed on the plankton that carry the currents, they depend to a large extent on the photosynthetic activity of small algae that house inside: the zooxanthellae.

But when the temperature rises, this symbiosis goes to waste. It is unknown if the polyps expel the algae or if they go away by themselves. In any case, when the coral-alga symbiotic relationship is broken, the reefs become long white extensions, a phenomenon known as whitening.

In 1911, unusually calm and hot weather conditions caused palpable lesions in coral reefs at Bird Key, Florida, and since then, sporadically and locally, whitening has been observed several times until, in 1982 and In 1983, a child – the famous South Hemisphere current – especially strong decimated corals globally , and since then nothing has been the same as before. The whitening began to be more frequent and expanded their impact zones, becoming global to the point of being able to affect in unison all the coral reefs of the planet.

Its relationship with the increase in water temperature is so clear that NOAA uses satellite data to predict its occurrence. According to its alert system, called Coral Reef Watch, the longest and most devastating global whitening began in October 2015 and lasted until last July.

For almost two years, the hot waters bathed the corals of the tropical seas without interruption, leaving a bleak panorama. In Australia, according to data collected by James Cook University, only 7% of the Great Barrier Reef has been unharmed. In the north, more than half of the corals have died. The island of Kiritimati, in Micronesia, has lost 80% of its corals and, according to the Coral Reef Watch, “it is estimated that, at most, 5% of the reefs will survive and recover from this phenomenon”.

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