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Damsels in distress on Australia's Great Barrier Reef

SYDNEY, May 11 — The smell of dead corals from the mass coral bleaching event occurring on Australia's Great Barrier Reef is masking the predators to the tropical damsel fish that call the reef home, Aussie researchers warned on Wednesday.

Researchers from James Cook University (JCU) in northern Queensland state and Sweden's University of Uppsala have been investigating the mechanism behind community structure changes on the Great Barrier Reef that have coincided with the current mass bleaching event.

Coral bleaching occurs when stress such as heat caused the animal to expel the symbiotic algae, loosing vital nutrients and energy reserves, thus color, leading to the wide scale loss of productive habitats for fish.

The coral host then becomes weak and susceptible to disease. When bleaching is prolonged, the animal can die.

"When we were doing the experiments we were bringing in some of this dead coral, and we started to get complaints from our friends in the laboratory because the stuff was so smelly," JCU Professor of Marine Ecology Mark McCormic told Australia's national broadcaster.

Damsels are covered in sensory cells on the front of their bodies, essentially tastebuds, which are important to learn about, and sense nearby predators, however the smelly, decomposing coral is playing havoc with these sensory systems, finding they did not respond to predator chemical cues.

"The smell that comes off degrading coral reef is actually masking some of the important chemicals that the animal is using to inform its decisions," McCormic said.

McCormic's research is pointing to significant changes to the reef's ecosystem, not only from the loss of coral life, but over predation of species which will potentially cause significant impacts to the community structure.

"The (bleaching) disturbance is on a scale that they probably haven't felt before," McCormic told Xinhua.

"Some species actually like living on dead coral and coral rubble, but there's not as many as you would have if you have a diverse reef."

"What we don't know now (however) is how widespread this is."

Coral reefs are one of the most important and productive marine ecosystems that the world depends on for tourism and fisheries sustainability, however, human induced climate change has been increasing the frequency of mass coral bleaching events.

The mass bleaching event occurring on Australia's Great Barrier Reef is the worst on record, with all but 7 percent remaining unaffected. Alarmingly, 90 percent of the norther reaches of the reef is likely to die, and thus, significantly affecting the community structure of the reef.

Scientists are now investigating if the coral degradation affects other fish species in the same way, and whether ones that are affected can cope from the loss of chemical cues and habitat in some other way. (PNA/Xinhua)


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