A robot diving deeper than any human diver has found that coral deep below Australia’s Great Barrier Reef is very healthy even though the shallower coral is suffering from storms, warming seas and pollution. The robot’s handlers hope the deeper coral will provide the "recruits" needed to naturally repair the shallower reefs.
"Up until now our knowledge was limited to the shallow reefs accessible by scuba diving," Ove Hoegh-Guldberg, chief scientist for the Catlin Seaview Survey, said in a statement announcing the findings. "In reality, that provided us with an incomplete picture."
The remote-operated vehicle, he added, allows scientists to study coral at depths between 90 and 300 feet, "revealing a wholly different picture which now includes the deep reef environment."
John Bruno, a University of North Carolina coral expert not associated with the survey, welcomed the work. "This is a popular idea," he said of deeper coral providing a refuge, "just not well tested."
Carden Wallace, a coral expert at the Museum of Tropical Queensland, added that it's not only the abundance but the diversity that surprised her. "Using the ROVs to film and collect samples at this scale is simply unprecedented in Australian waters," Wallace said.
That diversity includes corals that "are much flatter, more plate-like than the branching and domed shapes seen nearer the surface," said Pim Bongaerts of the University of Queensland’s Global Change Institute. "This is the corals responding to the reduced light conditions and spreading out to maximize their exposure to light.
"So far below the surface, the light is blue because all other parts of the spectrum have been filtered out," Bongaerts added. "It is a monochrome world until you turn on strong lights to reveal amazing, beautiful, fantastic colors."
The layer of coral just below the shallow reefs could be the key to repairing the reef system.
It "could provide coral recruits for the upper levels of the reef, providing a potential for them to help in the recovery," Bongaerts said. "At the moment we know little about the extent of larval movements between the shallow and deep reef, but we are seeing species that exist in both zones."
Related: 'Major decline' in Great Barrier Reef coral
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Bruno was optimistic that nature would play a role in recovery. "The deep water habitats can/will be a sort of refuge," he told NBC News, calling it "a natural source to repopulate shallow habitats that have been more affected by warming, bleaching, disease, storms, etc."
The findings come a month after the Australian Institute of Marine Science reported that the Great Barrier Reef has lost half its shallow-reef coral cover in the last 27 years.
The Catlin team, for its part, is planning six more surveys along the 1,600-mile-long reef system. It plans to later study reef systems around the world, using ROVs as well as cameras with 360-degree views.
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