Tue, Sep 11, 2018 - Page 9 News List

Areas of coral bleaching in Great Barrier Reef seem to be recovering

By Colin Bertram  /  Bloomberg

Following dire warnings of reef die-off after massive coral bleaching in 2016 and last year, Tourism and Events Queensland has issued a “positive update” on the status of Australia’s Great Barrier Reef, reporting that some areas affected are showing “substantial signs of recovery.”

The Reef and Rainforest Research Centre, a non-profit organization, has reported signs of recovery thanks to a milder 2017-2018 summer and cooperation between science, industry and government in supporting the recovery of the reef, a report released by the Queensland State Government on Wednesday last week said.

Stretching more than 2,300km along Queensland’s spectacular coastline, the Great Barrier Reef is the longest coral reef in the world and the first coral reef ecosystem to be awarded UNESCO World Heritage status.

Coral bleaching occurs when coral experience stress resulting from increased water temperatures or poor water quality. In response, the coral eject photosynthetic algae called zooxanthellae, which remove the distinctive color of coral. If the stress persists, the coral will die, according to the report, but if the stress returns to acceptable levels, some of the coral can reabsorb the zooxanthellae and recover.

The research center, in cooperation with the Association of Marine Park Tourism Operators, conducted detailed surveys at key dive tourism sites near the city of Cairns in 2016 and last year. The surveys indicate that some reefs that were quite strongly affected in the bleaching event are showing strong signs of improvement.

Coral bleaching occurs in multiple stages, according to research center managing director Sheriden Morris, ranging from the equivalent of a mild sunburn to coral mortality.

“When a reef is reported as ‘bleached’ in the media, that often leaves out a critical detail on how severe that bleaching is, at what depth the bleaching has occurred and if it’s going to cause permanent damage to the coral at that site,” Morris said in the statement, adding that the Great Barrier Reef “has significant capacity to recover from health impacts like bleaching events.”

Reports that the entire reef is dead due to severe bleaching are “blatantly untrue,” Morris said, but added that the continuation of a recovery is “contingent on environmental conditions” and that the reef “might suffer further bleaching events as the climate continues to warm.”

The full effect of the 2016 bleaching, which saw 30 percent of the reef’s shallow water coral damaged or destroyed, has not yet been fully assessed, a report released by Nature research journal on Tuesday last week said.

Deeper reefs are often considered a refuge from thermal anomalies such as those experienced in 2016 and last year, but the report said that shallow and deep reefs are under threat from mass bleaching events, adding that when the upwelling of warmer water stopped at the end of summer, even temperatures at depth rose to record-high levels. Researchers found bleached coral colonies down to depths of 40m beneath the ocean’s surface, the report said.

News of the recovery comes only two months after the research center cohosted the Great Barrier Reef Restoration Symposium in Cairns, which saw more than 300 scientists, engineers, and marine tourism representatives from 14 countries convene to focus on restoration and recovery of coral reef systems under threat from warming climates.

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