Reefs in Peril

Just off Australia’s northeastern coast lies the largest living structure in the world—the Great Barrier Reef. It stretches some 2,000 kilometers (1,200 miles) and was built entirely by coral polyps. These tiny marine organisms live in colonies and build hard skeletons under themselves, forming reefs (see How Corals Build Reefs). Coral reefs provide food and shelter for fish and other animals. Normally, the Great Barrier Reef is bursting with life. But recently, the reef has come under threat—along with others like it around 
the globe.

This March, biologists made an alarming discovery: They found that 93 percent of the Great Barrier Reef is suffering from coral bleaching, when the corals that make up a reef turn white. The scientists think many of the corals won’t survive.

“It’s the worst bleaching event in history,” says Ruth Gates, a marine biologist at the University of Hawaii.

Just off Australia’s northeastern coast lies the largest living structure in the world. It’s the Great Barrier Reef. It stretches some 2,000 kilometers (1,200 miles) and was built entirely by coral polyps. These tiny sea creatures live in colonies. They build hard skeletons under themselves, forming reefs (see How Corals Build Reefs). These structures provide food and shelter for fish and other animals. Normally, the Great Barrier Reef is bursting with life. But recently, the reef has come under threat. So have others like it around the globe.

Biologists made an alarming discovery this March. They found that 93 percent of the Great Barrier Reef is suffering from coral bleaching. That’s when the corals that make up a reef turn white. The scientists think many of the corals won’t survive.

“It’s the worst bleaching event in history,” says Ruth Gates, a marine biologist at the University of Hawaii.

When bleaching happens, the entire reef ecosystem suffers. Corals have trouble reproducing and become more vulnerable to disease. They can 
no longer support the reef inhabitants that 
rely on them. 

But Gates believes corals can make a comeback. She has discovered that some corals seem to withstand bleaching events better than others. Gates and her team are working on breeding these hardier corals, which could be implanted into dying reefs in the future. They’re also introducing corals to warmer temperatures in 
their lab to see if they can adapt. 

“We can give corals a leg up,” says Gates. “Someday, if we need to, we can put these corals in the ocean to help reefs survive.” 

The entire reef ecosystem suffers when bleaching happens. Corals have trouble reproducing. They also become more likely to fall victim to disease. They can no longer support the reef creatures that rely on them.

But Gates believes corals can make a comeback. She’s found that some types seem to bear bleaching events better than others. Gates and her team are working on breeding these hardier corals. The corals could be implanted into dying reefs in the future. The team is also growing corals in warmer waters in their lab. They want to see if the corals can adapt to higher temperatures. 

“We can give corals a leg up,” says Gates. “Someday, if we need to, we can put these corals in the ocean to help reefs survive.”