While coral on the iconic Great Barrier Reef and in the Kimberley region is currently at a low risk of bleaching, scientists are keeping a close eye on reefs along the west coast of Australia, where higher sea-surface temperatures are now causing some bleaching to occur.
The Australian Institute of Marine Science says thermal stress has been accumulating over the high-risk summer period and is expected to continue until April.
Institute coral ecologist, Dr James Gilmour, said the areas of concern include reefs in the Pilbara, Ningaloo, Shark Bay and the Abrolhos areas. All are off the coast of WA.
Bleaching is mainly the result of climate change
According to the World Wide Fund for Nature (WWF), coral bleaching is mainly the result of climate change and happens when corals lose their vibrant colours and turn white.
Even a relatively small change in water temperature can cause coral to stress and drive out algae. If the temperature stays high, the coral won’t let the algae back and the coral will die. Reefs damaged in this way seldom rehabilitate and the entire ecosystem deteriorates.
Dr Gilmour said low-level bleaching has already been observed in parts of Exmouth Gulf and in the Dampier Archipelago.
Clouds and rainfall have reduced some heat stress
“While cloud cover and rainfall from a recent tropical low has reduced some heat stress, the risk of bleaching will continue in the coming weeks in central to southern Western Australian reefs,” he stated.
The recurring threat of bleaching to WA coral reefs has galvanised collaborative efforts across government and research institutions, drawing on the most current observations and forecasts provided by the likes of the Bureau of Meteorology, CSIRO and others.
“In the coming weeks, we’ll have many eyes on the reef to report coral bleaching and in-water surveys will be conducted by several research agencies,” Dr Gilmour said.
“This week we are conducting in-water surveys around Ningaloo Reef (off the towns of Coral Bay and Exmouth) and this monitoring will extend to other reefs at risk in the coming weeks.
Public asked to report any sightings of bleaching
“We are encouraging people who are visiting these reefs to download our app – called ArcGIS Collector – and report any sightings of coral bleaching.”
Meanwhile, on the other side of Australia, temperatures are below bleaching thresholds for most of the Great Barrier Reef. The 2020-2021 summer has been characterised by a La Niña event – the colder counterpart of El Niño – which is forecast to last until autumn.
“This climate driver has meant above-average rainfall has been likely for eastern and some northern parts of Australia, meaning a lower risk of bleaching in the Kimberley and the Great Barrier Reef,” the Australian Institute of Marine Science said.