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A scuba diver swims over bleached corals in the Great Barrier Reef.
Ocean Agency/ XL Catlin Seaview Survey
Jim McMahon
A healthy section of the Great Barrier Reef
Jeff Hunter/Getty Images
Coral Crisis
Can scientists save the world’s coral reefs?

By Joe Bubar

The Great Barrier Reef is one of Earth’s greatest natural wonders. It’s the largest system of coral reefs in the world, stretching more than 1,400 miles along the east coast of Australia. The colorful underwater habitat provides food and shelter to countless marine (part of the ocean) animals. But in March 2016, scientists flying over the reef were alarmed by what they saw.

“Where you expected to see these wonderful colorful greens and browns and oranges of healthy coral, what you just saw was white,” says scientist Mark Eakin. He’s one of the authors of a report published a few months ago that highlights the extensive (widespread) damage to the Great Barrier Reef.

What the scientists saw is a condition called coral bleaching. It’s a warning sign that the reef is in serious trouble. Experts say rising ocean temperatures are mostly to blame.

REEFS AT RISK

Coral reefs look like plants, but they’re actually tiny animals that live in huge colonies. Their hard outer skeletons form reefs. Corals get their nutrients from tiny plant-like organisms (living things) called algae. The algae live inside corals and give them their color. But when the ocean gets too warm, corals release the algae. As a result, the corals get bleached white.

Scientists say that bleaching is becoming more widespread as oceans get warmer as part of global climate change. Some corals can recover from bleaching as the water cools in winter, but that is getting less likely as winter ocean temperatures rise too. Last year, more than 65 percent of the corals in the northern part of the Great Barrier Reef died.

“They’ve lost something that is an absolute gem,” Eakin says.

Coral reefs are one of the planet’s most important ecosystems. Reefs cover less than 1 percent of Earth’s surface, but they’re home to about one-quarter of all marine species. People who live in communities near reefs depend on them for food and to attract tourists.

Reefs worldwide suffer from pollution, overfishing, and other dangers, but scientists say climate change is the biggest threat. They predict that nearly 90 percent of all reefs will disappear by 2050.

This article appeared in the April 17, 2017, issue of Scholastic News Edition 5/6.