1

People and ecosystems

Understanding of the links between coral reef ecosystems, the goods and services they provide to people, and the wellbeing of human societies.

2

Ecosystem dynamics: past, present and future

Examining the multi-scale dynamics of reefs, from population dynamics to macroevolution

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Responding to a changing world

Advancing the fundamental understanding of the key processes underpinning reef resilience.

Coral Bleaching

Coral Bleaching

Coral Reef Studies

ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia

Phone: 61 7 4781 4000
Email: info@coralcoe.org.au

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Corals know how to attract good company. New research finds that corals emit an enticing fluorescent green light that attracts the mobile microalgae, known as Symbiodinium, that are critical to the establishment of a healthy partnership.

The study led by researchers at Japan’s National Institute for Basic Biology and the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE) sheds new light on the mechanism that brings corals and Symbiodinium together, for example, following a bleaching episode.

“Most reef corals can not function without Symbiodinium,” said Shunichi Takahashi from the National Institute of Basic Biology.

“Following the back-to-back mass bleaching events, images of bleached white coral contrasted with healthy, vibrantly coloured coral were widespread. The key difference between the two is the abundance of Symbiodinum in the coral’s tissue. Without sufficient Symbiodinum, which provide corals with nutrients via photosynthesis, the coral will starve.”

“Thirty percent of corals receive their Symbiodinium from their parents, the other seventy percent, need a different mechanism” said co-author Professor Andrew Baird of Coral CoE.

But what brings the two organisms together? Corals are stationary creatures, however Symbiodinium can move freely through the water column.

The study reveals that corals have evolved a cunning ability to draw the Symbiodinium to them.

The researchers used the chalice coral, Echinophyllia aspera, to test whether the green fluorescent light emitted by corals under certain conditions can signal the Symbiodinium in the water column to move towards them: a process known as “positive phototaxis.”

“Our research identifies a novel biological signaling tool that underlies the success of a relationship essential for healthy coral reef ecosystems, ” said Prof Baird.

The paper “Green fluorescence from cnidarian hosts attracts symbiotic algae” is published in the journal Proceedings of the National Academy of Sciences.

CITATION
Aihara Y, Maruyama S, Baird AH, Iguchi A, Takahashi S, Minagawa J (2019) Green fluorescence from cnidarian hosts attracts symbiotic algae. Proceedings of the National Academy of Sciences 116 (6): 2118-2123

IMAGES
Link to images here. Please credit as marked.

CONTACT FOR INTERVIEW
Prof Andrew Baird
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0) 400 289 770, +61 (0)7 4781 4857 (AEST/UTC +10)
Email: andrew.baird@jcu.edu.au

FOR FURTHER INFORMATION
Catherine Naum, Communications Manager
ARC Centre of Excellence for Coral Reef Studies
Townsville, QLD AUSTRALIA
P: +61 7 4781 5979, +61 (0)428 785 895 (AEST/UTC +10)
E: catherine.naum1@jcu.edu.au

New research reveals that global warming also affects fish who depend on corals.

The Great Barrier Reef (GBR) is revered for its kaleidoscope of colour. New international research led by PhD student Laura Richardson of the ARC Centre of Excellence for Coral Reef Studies at James Cook University reveals that coral bleaching events not only whitewash corals, but can also reduce the variety of fish occupying these highly-valued ecosystems.

The study was conducted by researchers at James Cook University and Lancaster University, U.K., who examined 16 reefs off Lizard Island, in the northern section of the GBR. The quantity and types of coral and fish species were surveyed before, during and after the 2016 mass bleaching event caused by a global heatwave.

“The widespread impacts of heat stress on corals have been the subject of much discussion both within and outside the research community. We are learning that some corals are more sensitive to heat-stress than others, but reef fishes also vary in their response to these disturbances,” said lead author Ms Richardson.

“Fish assemblages are significantly impacted by loss of coral cover as a result of bleaching events, and some fishes are more sensitive than others,” said co-author Prof Nick Graham of Lancaster University.

The loss of corals affected some types of fish more than others. Following the bleaching event, researchers recorded a sharp drop in the diversity of fish communities as the mix or species changed.

Fish that are highly dependent on branching corals, such as butterflyfish, declined the most.

“Prior to the 2016 mass bleaching event, we observed significant variation in the number of fish species, total fish abundance and functional diversity among different fish communities. Six months after the bleaching event, however, this variation was almost entirely lost,” said co-author Dr Andrew Hoey of ARC Centre of Excellence for Coral Reef Studies at James Cook University.

“Also known as ‘biotic homogenisation,’ this tendency towards individual and community similarity is increasingly considered one of the most pressing, but largely unrecognised, biodiversity crises faced globally.”

Citation: Richardson, LE, Graham, NAJ, Pratchett, MS, Eurich, JG, and Hoey, AS (2018). Mass coral bleaching causes biotic homogenization of reef fish assemblages. Global Change Biology,  doi:10.1111/gcb.14119

Link to video and images here. Please credit as marked.

Contacts for interviews:

Australia

Dr Andrew Hoey
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Townsville, QLD AUSTRALIA
P: +61 7 4781 5979 (AEST/UTC +10)
E: andrew.hoey@jcu.edu.au

UK

Ms Laura Richardson
Exeter University
Exeter, UNITED KINGDOM
M: +44 (0) 7384 634580 (GMT/UTC)
E: laura.richardson1@my.jcu.edu.au

Prof Nicholas Graham
Lancaster University, Lancaster Environment Centre
Lancaster, UNITED KINGDOM
M: +44 (0) 7479 438 914 (GMT/UTC)
E: nick.graham@lancaster.ac.uk

For more information:

Catherine Naum
Communications Manager
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Townsville, QLD AUSTRALIA
Tel: +61 (0)7 4781 6067
M: +61 (0) 428 785 895 (AEST/UTC +10)
E: catherine.naum1@jcu.edu.au

Scientists at the ARC Centre of Excellence for Coral Reef Studies at James Cook University say more needs to be done to protect vulnerable table corals on the Great Barrier Reef.

Researchers studying the role of table corals have found that they provide vital sun protection for large fish in shallow reef areas.

They found that the corals are so important that if lost, the fish that depend on them will leave the reef.

“The loss of table corals denies fishes important habitat, which they use to shelter from the sun, avoiding harmful UV-radiation, just as we might sit under an umbrella at the beach,” says study lead author James Kerry.

“Large fishes maintain balanced coral reef ecosystems, they’re the predators that help control fish populations,” says study co-author Professor David Bellwood.

Table corals are particularly vulnerable – and are the preferred meal of the Crown of Thorns Starfish. Credits: James Kerry

“These fish are important for reefs and people; lose your table corals and you lose your coral trout,” Professor Bellwood explains.

The scientists say this is particularly concerning as table corals are especially vulnerable to the pressures currently facing the Great Barrier Reef.

The corals are highly susceptible to ocean acidification and bleaching, and are the preferred meal of the destructive crown of thorns starfish.

Given their shape, table corals are also easily toppled and are often destroyed in cyclones.

“Ultimately we need to conserve table corals because they are the primary structure on the Reef that provides shelter from the sun’s harmful rays. However, because they are so vulnerable to climate change and other growing threats, this is going to be a major challenge,” James Kerry says.

“The research suggests that we need to do everything we can to promote the health of the Great Barrier Reef, and in doing so, reduce the multiple threats facing these valuable corals.”

 ~~~

Papers:
The functional role of tabular structures for large reef fishes: avoiding predators or solar irradiance? By J.T. Kerry and D.R. Bellwood is published in the journal Coral Reefs.
DOI 10.1007/s00338-015-1275-1
http://link.springer.com/article/10.1007/s00338-015-1275-1#page-1

Do Tabular corals constitute keystone structures for fishes on coral reefs? By J.T Kerry and D.R. Bellwood is published in the journal Coral Reefs
DOI 10.1007/s00338-014-1232-4
http://link.springer.com/article/10.1007%2Fs00338-014-1232-4

Images and video:
Image credit – James Kerry
https://www.dropbox.com/sh/3p6m9fzudy3whpq/AAB-XHZBhb_U1acvU5bGJfEOa?dl=0

Contacts:
James Kerry – mr.james.kerry@gmail.com +61 (0) 407475576
Prof David Bellwood – david.bellwood@jcu.edu.au +61 (0) 47814447
Eleanor Gregory – eleanor.gregory@jcu.edu.au +61 (0) 428 785 895

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Coral Reef Studies

ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia

Phone: 61 7 4781 4000
Email: info@coralcoe.org.au