Mass bleaching found at Kimberley reefs


Coral bleaching in the Kimberley. Photo: Kimberley Marine Research Station.

The Kimberley has recorded its first mass bleaching of inshore coral reefs, with about 50 per cent of reefs surveyed affected.

While Ningaloo Reef near Exmouth was recently declared free of bleaching, it has been found on coral further north.

The Kimberley Marine Research Station’s coral monitoring program, established in 2015 for the reefs within Cygnet Bay north of Broome,  discovered bleaching on recent visits to Montgomery Reef and Camden Sound.

Australian Institute of Marine Science research scientist James Gilmour said: “We’ve got a fairly good idea about which reefs have been worst affected and it certainly is the reefs in the Kimberley region; so that’s the far north reefs including the inshore and offshore reefs.”

Coral bleaching has had global effects over the past two decades and continues to impact the Great Barrier Reef, the Maldives and the Indonesian Archipelago.

According to the Great Barrier Reef Marine Authority, 93 per cent of the reef surveyed is affected by bleaching; decreasing in severity further south.

Dr Gilmour said this was largely due to the strong El Niño conditions warming ocean temperatures.

“Through satellite data of sea surface temperatures, you can really follow the movement of the very hot water through the Northern Hemisphere, down to Australia, from Eastern Australia,” he said.

“Towards the end of last year and early this year, you see the transition over to the Indian Ocean and Western Australia.

“The reason why this one is so significant is that it is truly a global event. It has only really happened two other times before and this one is probably the worst.”

Department of Parks and Wildlife senior researcher Shaun Wilson said the concern was these events could become more frequent and intense, causing the coral to be continually stressed and reducing its ability to recover.

“What some people may be hoping is that the corals that are there may be able to adapt, but evidence is suggesting that the time frames of increased frequency of bleaching events may not allow for adaption to occur,” Dr Wilson said.

According to the Bureau of Meteorology, sea surface temperatures across the Indian Ocean remain very warm and ocean temperatures around Australia are well above average.

Kimberley Marine Research Station managing director James Brown said this was significant for the Kimberley as the area had seen very little monsoonal activity.

“We normally get hot water around the 32 degree mark but we also normally get these up and down periods that are generated by monsoonal activity. We didn’t get any of that this year,” he said.

“They have a massive affect in mixing the surface water and the deeper water, and they drop the temperature of the inshore systems.

“The higher water temperatures that we experience up here just remained for months on end, and that was the inevitable precursor to an event never seen before.”

The mission for research stations and scientists is to continue to document the extent and the severity of the bleaching to fully understand the impact.

“The Kimberley Coast is really the last relatively untouched tropical marine environment left on the globe,” Mr Brown said.

“What that means is that we should be able to closely monitor change here, and if we do find change you have no other background fuzz that could be driving it such as deforestation or affects from an urban environment population.

“This should be the place that we all monitor and observe very closely to try and understand what really happens in terms of global effects.”


Categories: Environment