nine.com.au 8 Apr 17;
Tropical Cyclone Debbie has eased coral bleaching on parts of the Great Barrier Reef, marine biologists have found.
Surveys earlier this week of the Ribbon reefs off Lizard Island, 240km north of Cairns, revealed a drop of up to three degrees in coral-threatening sea temperatures, reports the Cairns Post.
Queensland-based marine biologists aboard the Spirit of Freedom in the Coral Sea reported sea temperatures of 28C, which eases stress on the coral and means less chance of bleaching.
The optimum sea temperature range for corals to live in is 23C to 29C, according to OceanWatch Australia.
As well as bringing deeper, cooler water to the surface of the Great Barrier Reef, the clouds formed by Cyclone Debbie also reduced light stress on the coral. The cyclone also absorbed energy from the surface water through heat transfer, which resulted in evaporative cooling.
Free-diver Audrey Buchholzer, of France, aboard the Spirit of Freedom, told the Post she was stunned by the “flashy” colours and kaleidoscope of marine life on the outer reef.
“I had to see it with my own eyes,’’ the 24-year-old said.
“I’d heard negative reports the reef was dead. That’s not true. There are patches of dead and bleached coral, but so much of it is alive and thriving.
“It is an underwater wonderland,” she said.
But marine experts have struck a note of caution on the benefits Cyclone Debbie could bring for the reef
Professor Terry Hughes, the director of the Australian Research Council Centre of Excellence for Coral Reef Studies, told Guardian Australia that the most severe coral bleaching occurred north of Cyclone Debbie's path.
“Cyclone Debbie has come a month too late and in the wrong place to prevent mass bleaching,” he said.
