Two years after an undersea heat wave burned large sections of the Great Barrier Reef and killed 30 percent of the coral reefs, scientists said the reef would be altered forever. But there may be hope.

On Thursday, April 19, PLOS Genetics revealed that some of the coral reefs were able to withstand the warmer temperatures.

Staghorn Corals Withstand Warm Temperatures

Although the heat specifically damaged staghorn corals, also known as Acropora millepora, this specific reef was able to recover and survive the difficult conditions. The latest analysis proves that the fast-growing coral is genetically different and would be able to survive for another 100 to 250 years, depending on how fast the planet warms up. 

Terry Hughes, a coral reefs expert of James Cook University, believes that the corals stand a chance as they are much tougher than the ones that died. 

"What we've just experienced [in the Great Barrier Reef] is one hell of a natural selection experiment," Hughes said. 

Staghorn corals live throughout the Great Barrier Reef, where the water can be about 5 degrees Celsius warmer than the water in the south. The corals also have the ability to migrate and can send out larvae to spots that aren't as warm. 

Unfortunately, if coral reefs continue to die, the underwater ecosystems will be affected as well as the millions of people who rely on them for various activities such as fishing and tourism.

According to the International Journal of Science, corals began to die immediately after the heat exposure has surpassed the dangerous threshold of degree heating weeks, which was 3-4 degrees Celsius-weeks. Nevertheless contact with temperatures of 6 degrees Celsius-weeks or more caused a record in the scale shift in the composition for coral accumulations, which conflicted responses to heat stress.

The Benefits of Zooxanthellae

The different temperatures actually help produce coral bleaching, which is what happens when the coral ejects an algae known as zooxanthellae that provides the corals with vibrant colors and the food that it needs to live.

When the coral experiences stress, warmer water temperatures, and even pollution, it dismisses the zooxanthellae and leaves the reefs looking bleached bone white. If the conditions return to their normal state, the algae will eventually recolonize and the entire system can recover. If the stress happens to be too harsh, it will cause the algae to stay away, which means the coral will begin to starve.