Corals with high levels of fat can withstand bleaching events: Study

By @iamkarlatecson on
Orbicella faveolata coral studied in the research
Orbicella faveolata coral studied in the research UWA

Faced with the continuing threats of annual bleaching events, corals containing high levels of fat or other energy reserves are found to withstand the impact of these events, according to a new study. 

The research, led by scientists from the University of Western Australia’s Oceans Institute, will help with predicting the persistence of coral reefs since it is critical to know their capability to recover from annual bleaching.

Coral bleaching events occur when sea temperatures rise as the result of climate change. This results in the breakdown of the symbiosis between the coral and their zooxanthellae, which gives corals most of their colour and threatens their survival. Tropical coral is extremely sensitive to heat stress, according to the study’s lead author Dr Verena Schoepf, a research associate from UWA’s Oceans Institute.

“Three global bleaching events have already occurred since the 1980s and will likely occur annually later this century. Therefore, it has become more urgent than ever to know how tropical coral can survive annual bleaching - one of the major threats to coral reefs today,” she said.

Bleaching events have already resulted in significant amounts of corals dying, causing impact to ocean ecosystems, Schoepf said. However, according to her, it is largely unknown whether corals could recover between annual bleaching events.

After simulating annual coral bleaching for the study, the team found that some species of corals, such as the mustard hill coral, were severely affected by repetitive bleaching events. However, they observed that other corals such as the finger coral and the mountainous star coral could recover quickly.

When coral is bleached, it no longer gets enough food energy, which results in the slowing down of its growth, Schoepf said. It also loses its fat and other energy reserves, just like humans during times of hardship. The coral then becomes increasingly weak and susceptible to disease, and when bleaching is prolonged, it can die. 

Over the next decades, coral bleaching events are likely to occur more and more frequently and increasingly affect coral reefs around the world, contributing to their worldwide decline, according to Dr Andrea Grottoli from the Ohio State University’s School of Earth Sciences. 

The university is also part of the said study, which was published today in the international journal Proceedings of the Royal Society B: Biological Sciences. Scientists from the ARC Centre of Excellence for Coral Reef Studies and the University of Delaware’s School of Marine Science and Policy are also part of the research team.

Last month, scientists from the University of Queensland warned that the Great Barrier Reef is in danger of being damaged in early 2016 due to widespread bleaching. This will be the third recorded global bleaching event in history, following the first major global event in 1998 and another in 2010. While the reef was spared during the second global event in 2010 due to storm activity which alleviated the heat stress, it may not be so lucky in 2016, the team said.

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