[Coral-List] New paper: Global warming transforms coral reef assemblages

Mark Eakin - NOAA Federal mark.eakin at noaa.gov
Wed Apr 18 14:39:52 EDT 2018

A new study published online today in Nature
<http://dx.doi.org/10.1038/s41586-018-0041-2> shows that corals on the
northern Great Barrier Reef experienced a catastrophic die-off following
the extended marine heatwave of 2016.

“When corals bleach from a heatwave, they can either survive and regain
their colour slowly as the temperature drops, or they can die. Averaged
across the whole Great Barrier Reef, we lost 30 per cent of the corals in
the nine month period between March and November 2016,” said Prof Terry
Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies
(Coral CoE) <https://www.coralcoe.org.au/person/terry-hughes>.

The scientists mapped the geographical pattern of heat exposure from
satellites, and measured coral survival along the 2,300-km length of the
Great Barrier Reef following the extreme marine heatwave of 2016.

The amount of coral death they measured was closely linked to the amount of
bleaching and level of heat exposure, with the northern third of the Great
Barrier Reef being the most severely affected. The study found that 29 per
cent of the 3,863 reefs comprising the world’s largest reef system lost
two-thirds or more of their corals, transforming the ability of these reefs
to sustain full ecological functioning.

“The coral die-off has caused radical changes in the mix of coral species
on hundreds of individual reefs, where mature and diverse reef communities
are being transformed into more degraded systems, with just a few tough
species remaining,” said co-author Prof Andrew Baird of Coral CoE at James
Cook University <https://www.coralcoe.org.au/person/andrew-baird>.

“As part of a global heat and coral bleaching event spanning 2014-2017, the
Great Barrier Reef experienced severe heat stress and bleaching again in
2017, this time affecting the central region of the Great Barrier Reef,”
said co-author Dr Mark Eakin of the U.S. National Oceanic and Atmospheric
Administration <https://www.star.nesdis.noaa.gov/star/Eakin_M.php>.

“We’re now at a point where we’ve lost close to half of the corals in
shallow-water habitats across the northern two-thirds of the Great Barrier
Reef due to back-to-back bleaching over two consecutive years,” said Prof
Sean Connolly of Coral CoE at James Cook University

“But, that still leaves a billion or so corals alive, and on average, they
are tougher than the ones that died. We need to focus urgently on
protecting the glass that’s still half full, by helping these survivors to
recover,” said Prof Hughes.

The scientists say these findings reinforce the need for assessing the risk
of a wide-scale collapse of reef ecosystems, especially if global action on
climate change fails to limit warming to 1.5‒2 °C above pre-industrial

The study is unique because it tests the emerging framework for the
Union for Conservation of Nature (IUCN) Red List of Ecosystems
which seeks to classify vulnerable ecosystems as ‘safe,’ ‘threatened’ or

“The Great Barrier Reef is certainly threatened by climate change, but it
is not doomed if we deal very quickly with greenhouse gas emissions. Our
study shows that coral reefs are already shifting radically in response to
unprecedented heatwaves,” said Prof Hughes.

The researchers warn that failure to curb climate change, causing global
temperatures to rise far above 2 °C, will radically alter tropical reef
ecosystems and undermine the benefits they provide to hundreds of millions
of people, mostly in poor, rapidly-developing countries.”

Publication here <http://dx.doi.org/10.1038/s41586-018-0041-2>


Link to video and images here
Please credit as marked.


Prof Terry Hughes
Director, ARC Centre of Excellence for Coral Reef Studies
Phone: +61 (0) 400 720 164 (AEST/UTC +10)
E-mail: terry.hughes at jcu.edu.au

Prof Sean Connolly
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0)7 4781 4242 (AEST/UTC +10)
Email: sean.connolly at jcu.edu.au <sean.connolly at jcu.edu.au>

Prof Andrew Baird
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0) 400 289 770 (AEST/UTC +10)
Email: andrew.baird at jcu.edu.au <andrew.baird at jcu.edu.au>

C. Mark Eakin, Ph. D.
U.S. National Oceanic & Atmospheric Administration
College Park, MD U.S.A.
Phone: +1 (301) 502 8608 (EST/UTC -5)
Email: mark.eakin at noaa.gov <mark.eakin at noaa.gov>


Catherine Naum
Communications Manager
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0)7 4781 6067, +61 (0) 428 785 895 (AEST/UTC +10)
Email: catherine.naum1 at jcu.edu.au <catherine.naum1 at jcu.edu.au>

C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
National Oceanic and Atmospheric Administration
Center for Satellite Applications and Research
Satellite Oceanography & Climate Division
e-mail: mark.eakin at noaa.gov <mark.eakin at noaa.gov>
url: coralreefwatch.noaa.gov
Twitter: @CoralReefWatch FB: Coral Reef Watch

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