Coral bleaching, which destroyed two-thirds of Australia’s Great Barrier Reef in 2016 and 2017, had a very drastic impact on the planet’s largest living structure. According to a study published in the Nature journal, the significant coral death rate from these years have significantly reduced the ability of corals to renew and continue to live, as they did before. During 2018, the number of new corals decreased by 89%, compared to the historical record.
“Dead corals do not make babies,” lead author and James Cook University and professor Terry Hughes said, as BBC News reported.
Researchers at ARC Center of Excellence for Coral Reef Studies in Australia have been stunned by the decline in numbers of new corals. They recorded such a sudden drop for the first time.
Shocking collapse of ecosystem processes
Baird added that the shocking collapse of ocean ecosystem processes was scientifically documented for the first time. Coral bleaching occurs when warm water forces corals to expel algae that provide them with colour and nutrients. Although the reefs can recover from such events, it takes about ten years. Since 1998, the Great Barrier Reef has suffered four such bleaching cycles, and if greenhouse gas emissions continue at current levels, we may encounter two bleaching cycles every decade from 2035 onwards. Recent bleaching has covered 900 kilometres of the reef and made it difficult for young corals to replenish the affected coral populations.
“Babies can travel over vast distances, and if one reef is knocked out, there are plenty of adults in another reef to provide juveniles,” Baird told BBC News. “Now, the scale of mortality is such that there’s nothing left to replenish the reef.”
The bleaching affected each species of corals differently, for example, the new Acropora corals decreased their number by 93%. These are the so-called table-shaped corals creating the 3D structure of the reef, which, moreover, provide a habitat for a variety of fish, from coral trout to clownfish.
“We’ve always anticipated that climate change would shift the mix of coral,” Hughes told National Geographic. “What’s surprised is how quickly it’s happening. It’s not happening in the future. It’s something that we’re now measuring.”
Source: ecowatch.com, bbc.com/news/world-australia-47809500