Western Australian scientists say it’s now clear that global ocean warming is catching up with Kimberley coral reefs which, until the extreme marine heatwave of 2016, had been largely spared from major bleaching.
A research project for the Western Australian Marine Science Institution’s Kimberley Marine Research Program has found that coral calcification rates have been remarkably stable over the last 100 years with Kimberley corals growing at rates similar to corals from less extreme reef environments.
However, last year’s mass coral bleaching event was the first time that regional-scale bleaching has been documented on inshore Kimberley reefs, leading researchers to confirm that Kimberley corals are vulnerable to marine heatwaves and climate change despite their ability to withstand temperature extremes in the short term.
Most coral reefs in the southern Kimberley had 30-60% bleaching during the first natural bleaching event in summer 2016 but the full extent of coral mortality and recovery is yet to be determined.
Bleached coral communities near Cygnet Bay, Kimberley, in April 2016.
According to co-researcher, Dr Verena Schoepf from The University of Western Australia, most of the severely bleached corals observed in April near Cygnet Bay in the Kimberley have now died, with the Australian Institute for Marine Science reporting similar findings from Scott Reef.
“Kimberley corals have a remarkable ability to thrive under extreme conditions that many other corals would not survive,” Dr Schoepf said. “However, it is important to understand that even these naturally stress-tolerant corals are still threatened by the increasing frequency of extreme marine heatwaves events associated with climate change.”
|Bleached and dead staghorn coral exposed at low tide near Cygnet Bay, Kimberley, in April 2016. (Chris Cornwall)|
The researchers found that although Kimberley corals are not immune to bleaching, extreme daily temperature swings enhance the heat stress resistance of intertidal corals. They also found that intertidal corals recovered much better from the natural bleaching event in 2016 than subtidal corals.
“We are now working to understand the physiological and genetic mechanisms underlying the exceptional heat tolerance of Kimberley corals in a collaboration with Curtin and Stanford Universities,” Dr Schoepf said.
Results of the final WAMSI report Resilience of Kimberley coral reefs to climate and environmental extremes: past, present and future are due to be published by the end of the year.
Dr Schoepf will be presenting the latest results at a Lunch and Learn information session at the Department of Parks and Wildlife, Kensington, Western Australia on 27 July, 2017.
The latest project update can be found at www.wamsi.org.au/calcification
Dr Verena Schoepf investigating intertidal coral communities near Cygnet Bay, Kimberley.
The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.