For the second year in a row, the Great Barrier Reef is suffering from a mass bleaching that poses great threat to its overall health.
The bleaching is part of a global event affecting the world’s coral reefs over the past two years.
Experts from the Great Barrier Reef Marine Park Authority spent six hours yesterday flying over the Reef between Townsville and Cairns, alongside researchers from the Australian Institute of Marine Science.
The aerial survey of the Reef, the first for 2017, found severe bleaching in offshore reefs from north of Ingham to the northern extent of the survey near Cairns.
This year more bleaching is being observed in this central part of the Reef, which last year escaped widespread severe bleaching.
Marine Park Authority director of reef recovery Dr David Wachenfeld said the survey confirmed anecdotal reports from visitors and reef surveys of bleaching from marine park rangers and commercial operators.
“Mass bleaching is occurring on the Great Barrier Reef for the second consecutive year,” he said.
“How this event unfolds will depend very much on local weather conditions over the next few weeks.
“Importantly, not all bleached coral will die. As we saw last year bleaching and mortality can be highly variable across the 344,000 square kilometre Marine Park — an area bigger than Italy.”
Dr Neal Cantin from the Australian Institute of Marine Science (AIMS) said the recurrence of widespread coral bleaching in back-to-back summers indicated there was not enough time between last year’s extreme heat event for the corals to fully recover.
“We are seeing a decrease in the stress tolerance of these corals,” Dr Cantin said. “This is the first time the Great Barrier Reef has not had a few years between bleaching events to recover.
“Many coral species appear to be more susceptible to bleaching after more than 12 months of sustained above-average ocean temperatures.”
Marine Park Authority experts and scientists from the ARC Centre of Excellence for Coral Reef Studies will take to the sky again next week to resurvey 1150 reefs along the entire Great Barrier Reef.
The Marine Park Authority is working with AIMS to develop standardised operating practices to ensure a consistent approach to the scientific assessment of extent and impact of bleaching events.
Dr Wachenfeld said this bleaching highlighted the importance of global action on climate change.
“It’s vital the world acts to implement the Paris Agreement to reduce greenhouse gas emissions,” he said.
“It also highlights the critical importance of the work being done under the Reef 2050 Plan and the Authority’s ongoing management to build Reef resilience — such as zoning and controlling coral-eating crown-of-thorns starfish.
“Anyone out on the water can help protect the Reef by following the zoning rules and responsible reef practices and leaving plant-eating fish to help control seaweed and enable coral larvae to settle and create new colonies.”