A flotilla of vessels carrying 300 scientists is on the top half of the Great Barrier Reef trying to find ways to the spread of a massive coral bleaching.
Parts of the World Heritage site have been hit by the worst bleaching — a process by which the algae in coral is killed off by warmer water — in 15 years.
This is caused by an increase in water temperature at least partly caused by El Niño weather conditions. The Great Barrier Reef Marine Park Authority has raised a high threat alert from bleaching.
“So far we have collectively undertaken twelve separate missions using research vessels,” says says Professor Morgan Pratchett from the ARC Centre of Excellence for Coral Reef Studies.
By the end of this month they will have examined close to 90 reefs.
The underwater surveys are revealing very high levels of bleaching from Cairns to Torres Straits.
Last week, divers found that 75% of the corals were bleached on multiple reefs near Port Douglas and nearly 50% near Cairns. South of Cairns, the bleaching is 10% to 30%.
These amounts closely match the broader aerial surveys of more than 750 reefs being conducted by the National Coral Bleaching Taskforce.
Dr Neal Cantin, a research scientist at the Australian Institute of Marine Science, is surveying mildly bleached reefs north of Townsville this week.
“When bleaching is mild, the corals can regain their colour as water temperatures drop, and most of them will survive,” he says.
“Our coral experts have the skills to measure how different species are responding — some are susceptible and others are robust.”
However, bleaching is approaching 80% to 100% around Lizard Island.
“This is by far the worst bleaching crisis we’ve seen, eclipsing the 2002 event,” says Dr Anne Hoggett, co-Director of Australian Museum’s Lizard Island Research Station.