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InternationalDeadly bleach

May 1, 2017

Coral in the Great Barrier Reef

Coral in the Great Barrier Reef









Bleaching is devastating the coral in the Great Barrier Reef. Concerned scientists report that nearly two-thirds of the reef has been badly damaged this year.

The Great Barrier Reef off the northern coast of Australia in Queensland is the largest living organism on earth. It is 2,300 kilometers long and supports 600 different types of hard and soft coral.

Coral are curious animals. They are polyps that attach themselves to rocks and live together in a community of other like polyps. They form a skeleton and never move.

To live, coral depend on a type of algae, zooxanthellae. Zooxanthellae live inside coral tissue and provide up to 90% of the energy that coral require. However, in both 2016 and 2017, the increase in temperature of the ocean water in the Great Barrier Reef has caused the coral to expel the zooxanthellae. Without this algae, coral lose nutrients and whiten. This is called bleaching.

A rise of one- degree Celsius in ocean water doesn’t seem like a cause for concern, but scientists first reported the bleaching in 2016 in the northern part of the reef. This year the ocean temperature continued to be warmer than normal and the bleaching event moved south to the middle of the Great Barrier Reef. Along with coral, other reef marine life has died.

Coral can survive bleaching, but they need time to recover. Fast-growing coral can recover in about ten years, but two years in a row of overly warm ocean water is not just bleaching coral, but also killing them. Scientists are blaming the effects of global warming.

Photographer: Gary Wagenblast

Published May 2017

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