World's Coral Reefs Hit By a Fourth Mass Bleaching Event, NOAA Says

The National Oceanic and Atmospheric Administration on Monday declared that Earth is in the midst of a '4th global coral bleaching event' that's been documented over the last 14 months in every major ocean basin, including off Florida in the United States, in Australia's Great Barrier Reef and in the South Pacific. 'As the world's oceans continue to warm, coral bleaching is becoming more frequent and severe,' said Derek Manzello, a coral reef ecologist who coordinates NOAA's Coral Reef Watch Program, in a news release. 'When these events are sufficiently severe or prolonged, they can cause coral mortality, which hurts the people who depend on the coral reefs for their livelihoods.' NBC News reports: Corals are critical ecosystems that support a vast array of fish and aquatic species, which help feed coastal communities and attract tourists. The economic value of reefs is estimated at $2.7 trillion per year, according to a 2020 report from the Global Coral Reef Monitoring Network. 'They protect our coastline. They offer protection from storms and hurricanes. They have a great value for our economy and safety,' [Ana Palacio, an assistant scientist at the Cooperative Institute for Marine and Atmospheric Studies, a research institute that is based at the University of Miami in partnership with NOAA] said.

In Florida, as sea surface temperatures spiked, bleaching started early in the season, experts said. 'Normally, bleaching will be observed in the Northern Hemisphere around August and September. We started to observe bleaching in July last year,' said Phanor Montoya-Maya, a marine biologist with the Coral Restoration Foundation, an organization that collects, restores and repopulates corals. Palacio said the region saw widespread mortality of elkhorn and staghorn corals, two species that have been the focus of restoration efforts. 'In some locations, about 20% of those populations survived,' Palacio said of restored corals. 'We're concentrating our hope on why those corals survived and what they can tell us about resistance and how corals can be more resilient.'

The last global coral bleaching event happened in 2014 and lasted until 2017. More than 56% of global reef areas saw temperatures that could cause bleaching during that time period. In an email on Monday, Manzello said that 54% of the world's coral reef areas had experienced bleaching-level heat stress in the past year and that the event was poised to become the worst bleaching event in history. 'The percentage of reef areas experiencing bleaching-level heat stress has been increasing by roughly 1% per week,' Manzello said. 'It is likely that this event will surpass the previous peak.'

Montoya-Maya said a bleaching alert is already in effect in Florida, even earlier than last year. He said the Coral Restoration Foundation was preparing for a busy summer responding to another bleaching event. The natural pattern of El Nino has begun to dissipate and NOAA's Climate Prediction Center estimates there is a 60% chance La Niaa develops this summer, which could help cool Atlantic waters and allow some corals to recover, at least temporarily.

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