Predicting coral reef futures under climate change

January 14, 2015, ARC Centre of Excellence in Coral Reef Studies
Healthy coral dominated reef in the Indian Ocean. Credit: Image: Nicholas Graham

Researchers examining the impact of climate change on coral reefs have found a way to predict which reefs are likely to recover following bleaching episodes and which won't.

Coral bleaching is the most immediate threat to reefs from climate change; it's caused when ocean temperatures become warmer than normal maximum summer temperatures, and can lead to widespread death.

A key unanswered question has been what dictates whether reefs can bounce back after such events, or if they become permanently degraded.

An international team of scientists found that five factors could predict if a reef was likely to recover after a bleaching event.

"Water depth, the of the reef before disturbance, nutrient levels, the amount of grazing by fish and survival of juvenile corals could help predict reef recovery,"says study lead author, Dr Nicholas Graham from the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Australia.

"Remarkably, the two most easily measured variables, water depth and the physical structure of the reef before disturbance, predicted recovery with 98% confidence," Dr Graham says.

As part of the research, published in the journal Nature, researchers from Australia, the United Kingdom and France examined nearly 20 years of coral reef data gathered from the Seychelles.

Data was collected before and after an unprecedented event in 1998, in which 90 per cent of the country's corals across 21 reefs were lost.

Macroalgae dominated reef in the Seychelles. Credit: Image: Nicholas Graham

Of the reefs affected by the episode, twelve recovered while nine did not. The event had a significant impact on the biodiversity of local fish populations, which changed substantially when reefs did not recover.

From their data the researchers identified thresholds for the factors that dictated whether reefs would recover.

"Putting numbers on the threshold points at which reefs either recover or degrade helps predict reef futures under climate change," Dr Graham says.

Study co-author, Dr Shaun Wilson from the Department of Parks and Wildlife, Western Australia adds that the findings are important for predicting reef futures under climate change.

"The beauty of this study is that easily acquired measures of reef complexity and depth provide a means of predicting long term consequences of ocean warming events," Dr Wilson says.

Reef recovering in the Seychelles after mass bleaching event. Credit: Image: Nicholas Graham
"The ability to predict which reefs have the capacity to recover is really important for mapping of winners and losers, and risk analysis"

Co-author Dr Aaron MacNeil from the Australian Institute of Marine Science says the insights can be applied to studies and management aimed at improving the outlook of around the world.

"This gives reef management a major boost in the face of the threats posed by and, encouragingly, suggests people can take tangible steps to improve the outlook for reefs," Dr MacNeil says.

"By carefully managing reefs with conditions that are more likely to recover from climate-induced bleaching, we give them the best possible chance of surviving over the long term, while reduction of local pressures that damage corals and diminish water quality will help to increase the proportion of reefs that can bounce back."

Explore further: Environmental bleaching impairs long-term coral reproduction

More information: Predicting climate-driven regime shifts versus rebound potential in coral reefs, Nicholas AJ Graham, Simon Jennings, M Aaron MacNeil, David Mouillot and Shaun K Wilson, Nature: http://nature.com/articles/DOI: 10.1038/nature14140

Related Stories

Remote reefs can be tougher than they look

April 4, 2013

(Phys.org) —Isolated coral reefs can recover from catastrophic damage as effectively as those with nearby undisturbed neighbours, a long-term study by marine biologists from the Australian Institute of Marine Science (AIMS) ...

Managing reefs to benefit coastal communities

December 3, 2014

Coral reefs provide a range of benefits, such as food, opportunities for income and education, but not everyone has the same access to them, according to a new study conducted by the ARC Centre of Excellence for Coral Reef ...

Recommended for you

Galactic center visualization delivers star power

March 21, 2019

Want to take a trip to the center of the Milky Way? Check out a new immersive, ultra-high-definition visualization. This 360-movie offers an unparalleled opportunity to look around the center of the galaxy, from the vantage ...

Ultra-sharp images make old stars look absolutely marvelous

March 21, 2019

Using high-resolution adaptive optics imaging from the Gemini Observatory, astronomers have uncovered one of the oldest star clusters in the Milky Way Galaxy. The remarkably sharp image looks back into the early history of ...

When more women make decisions, the environment wins

March 21, 2019

When more women are involved in group decisions about land management, the group conserves more—particularly when offered financial incentives to do so, according to a new University of Colorado Boulder study published ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

BrassOrchid
1 / 5 (4) Jan 14, 2015
In 3,000 years, nearly all the coral reefs will be dead.
We cannot change that. We can only panic and assign blame.
Shootist
1 / 5 (2) Jan 14, 2015
corals have been around what, 500 million years? the climate has never changed in 500 million years? Give me a break.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.