More shocking news from the northern Great Barrier Reef where scientists say that on some reefs surveyed, 95 percent of the coral is dead.
Scientists from James Cook University have confirmed that coral bleaching on the Great Barrier Reef is much more severe than first thought.
Six months after the extreme underwater heatwave of 2015/2016, researchers from the ARC Centre of Excellence for Coral Reef Studies at James Cook University returned to the reefs surveyed back in March at the height of the bleaching event.
In the aftermath of the worst coral bleaching ever recorded on the Great Barrier Reef, they found that “many of the bleached corals have died in the northern third of the Reef. The large-scale devastation is now being compounded by disease infecting the damaged corals and by coral predators”. They have released unique footage of the extent of the bleaching in March and April.
“Millions of corals in the north of the Great Barrier Reef died quickly from heat stress in March and since then, many more have died more slowly,” says Dr Greg Torda, whose team recently returned from re-surveying reefs near Lizard Island.
“Six months after the peak bleaching, the corals have either regained their algal symbionts and survived, or they have slowly starved to death without the nutrition the algae provided to them,” said Torda.
“On the reefs we surveyed close to Lizard Island, the amount of live coral covering the reef has fallen from around 40 percent in March, to under five percent now.
“In March, we measured a lot of heavily bleached branching corals that were still alive, but we didn’t see many survivors this week,” said Dr Andrew Hoey, who is currently working from Lizard Island Research Station.
“On top of that, snails that eat live coral are congregating on the survivors, and the weakened corals are more prone to disease. A lot of the survivors are in poor shape.”
“As we expected from the geographic pattern of bleaching, the reefs further south are in much better shape,” says Professor Andrew Baird who led the re-surveys of reefs in the central section of the Great Barrier Reef.
“There is still close to 40 percent coral cover at most reefs in the central Great Barrier Reef, and the corals that were moderately bleached last summer have nearly all regained their normal colour.”
The final death toll from the bleaching in the north will not be known until all surveys are completed in mid-November.