St. Lucy's Priory High School

Coral populations in Great Barrier Reef depleting

The Great Barrier Reef, located off the coast of Queensland in northeastern Australia, is the largest coral reef ecosystem on Earth and a UNESCO World Heritage site. Stretching more than 300,000 square kilometers, it boasts more than 3,000 reefs, 600 islands, and 300 coral cays that countless species of marine life call home.

Over the past year, approximately 38 percent of the world’s coral reefs have been bleached due to warming waters caused by El Niño and climate change. This devastating trend has continued throughout the year, contributing to the largest global coral bleaching event in history.

The massive die-off has taken its toll in Australia, with up to 93 percent of the Great Barrier Reef affected by the bleaching. This event has propelled the reef into the growing danger of extinction.

“The corals in the remote far north of the reef experienced extremely hot conditions this summer, and were effectively bathed in warm water for months, creating heat stress that they could no longer cope with,” stated Russell Reichelt, the chairman of the Great Barrier Reef Marine Park Authority.

Bleaching occurs when coral experience extreme stress caused by changes in environmental factors such as temperature, light, or nutrients. In these adverse conditions, they release symbiotic algae, called zooxanthellae, stored within their tissues. The tiny algae supply the corals with most of their food, as well as their color, resulting in the white reefs.

However, rising water temperatures are not scientists’ only cause for concern. As the concentration of carbon dioxide in the atmosphere rises due to the emission of fossil fuels, more of the gas seeps into the ocean. This lowers the pH of the water, making it more acidic, and proves to be more challenging for reef-building organisms to construct their hard skeletons.

Overfishing, mining, and nutrient runoff from farms as well as industrial chemicals have all contributed to the destruction and decline of the Great Barrier Reef for the last several decades.

In an effort to combat the damage, a team of scientists at the University of Hawaii’s Institute of Marine Biology are currently attempting to assist evolutionary processes and breed a more resilient coral that can withstand climate change.

–Audrey Strople


Lewis, Sophie. “The Great Barrier Reef is not actually dead.” CNN. Cable News Network, 14 Oct. 2016