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UNC professor's research finds drastic change is necessary to save coral reefs


Fish swim at Little Cayman Reef, one of many reefs cited in the research led by UNC Professor John Bruno. Photo by Isabelle Côté. 

The coral reefs are dying, and the world's small-scale quick fixes are failing. A new study led by UNC Professor John Bruno details the techniques being used to combat coral reef depletion and how they are not enough to keep reefs from perishing. 

The study began with a group of UNC undergraduates about two years ago and has since developed into a multi-university research study. The group studied coral reefs off the coast of Florida and in the Caribbean to learn if the current policies of protection were doing their job. 

The main problem causing the reefs to die is ocean warming, Bruno said. The theory behind managed resilience, according to the study, is to cut back other stressors, like overfishing and polluting, so the reefs can better recover and are more “resilient” to damages done by ocean warming. 

“The only problem is that when we looked critically at studies that test this idea, there is no evidence that it works,” said Isabelle Côté, professor at Simon Fraser University. 

Côté said that, unfortunately, climate change is one of the hardest environmental challenges to tackle. 

"So lots of people prefer to look at secondary, more tractable, causes of environmental change and there is a general feeling that if we tackle enough of these local, minor threats, then ecosystems might be able to cope with climate change," Côté said. "This is simply not true.” 

Côté said these practices still are important and often lead to higher fish populations as well as a multitude of other benefits. Bruno, Côté and Lauren Toth's research found hundreds of field studies that documented the strong positive connection between high ocean temperatures and coral bleaching. 

As a result, Bruno said the larger issue of ocean warming is just too big for these smaller initiatives to handle. 

“I think they are just getting swamped by the much stronger, much bigger, more pervasive signal of (ocean) warming,” Bruno said.

Coral reefs are not only, as Bruno puts it, the forests of the ocean, they are also the centre of the ecosystem. 

“They create this three-dimensional space, and without the corals, you wouldn’t have turtles and fishes and invertebrate animals, millions of species inhabit reefs but they are all dependent on the corals, mostly just for a place to hide” Bruno said. 

Bruno said they build a big buffer. 

"Sometimes it's a couple hundred meters offshore, and sometimes it’s 10 miles offshore, but it’s like a sea wall, so when the waves come in, they break on the reef and then they don’t break on the shoreline so it’s a really important natural buffer to coastal villages and so when the corals die, the reefs erode pretty quickly and then the waves start going over the reef and then breaking on the shoreline.” 

This can have devastating impacts for coastal erosion. Furthermore, the rising sea levels and this coral erosion is making the problem much worse. Bruno said our options are very limited and only extreme action could help restore our reefs. 

“We have to mitigate greenhouse gas emissions. For corals, we have to go almost to zero net emissions by the middle of the century. So, by the time you are a grandparent we have to be at zero net emissions and we probably have to develop technology to extract CO2 from the atmosphere to go into negative emissions,” Bruno said. 

The rise in water temperature is the overarching theme of this whole issue, and instead of avoiding it and focusing on smaller, less crucial details, Bruno said we must take greater steps. 

“We need to save ourselves," Bruno said. "I mean ultimately, nobody is going to care about protecting the corals or saving the fishes at the end of the century if we see two or three or four degree Celsius warming, and it’s gonna be really bad for people. Not all people, really rich people which just like isolate themselves from it. Overall, humanity needs to do this to save themselves.”

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