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2018-01-04. Global Warming’s Toll on Coral Reefs: As if They’re ‘Ravaged by War’.

posted Jan 9, 2018, 9:18 AM by Alan Gould   [ updated Jan 16, 2018, 1:51 PM ]
By Kendra Pierre-Louis and Brad Plumer, The New York Times. For GSS Losing Biodiversity chapter 7. Excerpt: ...reefs, home to a quarter of all marine fish species, are now increasingly threatened as rising ocean temperatures accelerate a phenomenon known as coral bleaching. Large-scale coral bleaching events, in which reefs become extremely fragile, were virtually unheard-of before the 1980s. But in the years since, according to a study published Thursday in the journal Science, the frequency of coral bleaching has increased to the point that reefs no longer have sufficient recovery time between severe episodes. ...During bleaching events, overheated seawater causes corals to part ways with symbiotic plantlike organisms called zooxanthella that live inside of them. In addition to giving coral reefs their bright colors, zooxanthella also provide corals with oxygen, waste filtration, and up to 90 percent of their energy. Absent zooxanthella, corals not only take on a ghostly pallor, hence the term bleaching, but they are also more susceptible to death. ...Typically, it takes 10 to 15 years for the fastest-growing corals to recover after a severe bleaching event. Larger corals that provide shelter for bigger fish can take even longer to grow back. As bleaching events become more frequent, reefs are unlikely to get that needed reprieve. Earth’s average temperature has increased 1 degree Celsius, or 1.8 degrees Fahrenheit, above preindustrial levels, and the median time between severe bleaching events is now just six years, the Science study found.... https://www.nytimes.com/2018/01/04/climate/coral-reefs-bleaching.html