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Western Australian reefs feel the heat from global bleaching event

Western Australian reefs feel the heat from global bleaching event


North Western Australian coral reefs are now feeling the effect of the 2016 global coral bleaching event. Scientists aboard AIMS research vessel Solander at Scott Reef, an isolated coral reef system located 250 km off the northwest coast of Western Australia, are reporting 60-90% of corals in water depths of up to 15 m have bleached and that wide-spread mortality is already evident.

Varied levels of coral bleaching were observed mid-March during an AIMS regional assessment of a number of reefs and shoals between Darwin and Broome, and at Browse Island. Current reports indicate bleaching at sites along the Kimberley coast as well as offshore locations such as Christmas Island, Cocos Islands, and Seringapatam Reef.

Preparations for large-scale coral bleaching in Western Australia began when predictions of a global bleaching event reaching Australia first emerged. In November 2015, over 40 scientists from research institutions and management agencies across the state convened to develop a large-scale strategy to document the distribution and severity of the bleaching. Scientists predict that warm water conditions causing bleaching will continue until the end of April, particularly in the north.

Now in effect, aerial and in-water monitoring activities are being conducted by collaborators including: Australian Border Force; Australian Institute of Marine Science; Bardi Jawi Indigenous Rangers; CSIRO; Curtin University; Kimberley Marine Research Station; Murdoch University; Parks Australia; University of Western Australia; West Australian Museum; WA Department of Fisheries; and WA Department of Parks and Wildlife. 

Predictions, collaborations and preparations

To assist with co-ordinating the streams of information from multiple sources, a new reporting tool has been developed by AIMS. The Coral Bleaching App works on smart phones and tablets via a
map-based interface. It allows users to enter reports of bleaching and upload photographs into the state-wide database. The tool is freely available for anyone, including members of the public, to download and use to report bleaching observations at their location. The results will be displayed via a publicly-available online map.

AIMS Research

In addition to conducting preliminary baseline surveys and documenting and assessing the bleaching at several key WA locations, AIMS is contributing to broader knowledge regarding the impact of bleaching on Western Australian coral reefs. Using semi-permanent photo transects, in situ loggers and satellite data (through The Pawsey Supercomputing Centre), AIMS and our collaborators will:

  • assess the impact and recovery of coral communities to determine thermal tolerances of different coral species and morphologies;
  • assess local and regional differences in community resilience using fine-scale temperature information gained from temperature loggers recording throughout the bleaching period; and,
  • compare satellite imagery of the reefs to in situ surveys and develop models to better predict bleaching severity through remote imaging.

AIMS expertise and capabilities are making an important contribution to the collaborative bleaching research effort in Western Australia. The RV Solander is delivering our scientists and collaborators to some of the most isolated coral reefs in Australian waters to document the extent of bleaching, as she has done since commissioning in 2007. The data gathered during these trips provides a valuable insight into the resilience of isolated reef communities in some of the world’s most pristine settings. 

Scott Reef – a unique ecosystem

Scott Reef is Australia’s largest oceanic reef system. It is isolated, and rises from deep water on Australia’s Northwest shelf, approximately 250km from the West Australian coastline. Its isolation from many direct human pressures makes it a unique and valuable system for research. AIMS, in collaboration with other research institutions and industry, has been monitoring and investigating Scott Reef for over 20 years, resulting in one of the most comprehensive, long-term datasets for a coral reef ecosystem.

AIMS began a formal monitoring program at Scott Reef in 1996. In 1998, the reef suffered moderate to severe bleaching during the first global bleaching event. Over 80% of coral cover was lost during this period. Extensive research and monitoring over the following years provided vital information on how isolated coral reefs respond after catastrophic bleaching events, information that is critical to the management of reefs globally. The reef took about 12 years to recover.

The current collaborative research program at Scott Reef will provide valuable information on how reefs are responding to warming events of increasing frequency, length and severity providing some sobering insights into the future of other ecosystems in the face of a rapidly changing global climate. 

A large table coral is severely bleached at Scott Reef. Research divers are assessing the extent and severity of the bleaching by conducting surveys at several sites across the reef. (Credit Nick Thake)

A large table coral is severely bleached at Scott Reef. Research divers are assessing the extent and severity of the bleaching by conducting surveys at several sites across the reef. (Credit Nick Thake)

Different stages of bleaching in the one small area. Corals that are bright white or bright blue are stressed corals. Those that appear green/yellow have already died are being overgrown with algae.

Different stages of bleaching in the one small area. Corals that are bright white or bright blue are stressed corals. Those that appear green/yellow have already died are being overgrown with algae.

Coral mortality has already claimed many of these corals. Transitioning through the bright whites of bleaching, the coral polyps have now died and the colonies are being overgrown with algae. Approximately 50% of the colonies at this site (Inner East Hook) had died.

Coral mortality has already claimed many of these corals. Transitioning through the bright whites of bleaching, the coral polyps have now died and the colonies are being overgrown with algae. Approximately 50% of the colonies at this site (Inner East Hook) had died.

Scott Reef is experiencing severe bleaching. Approximately 90% of the coral community is affected and coral mortality is occurring.

Scott Reef is experiencing severe bleaching. Approximately 90% of the coral community is affected and coral mortality is occurring.

Early stage bleaching off Browse Island. Regional assessments in North West of Australia found early signs of bleaching in March 2016.

Early stage bleaching off Browse Island. Regional assessments in North West of Australia found early signs of bleaching in March 2016.