Coral Reefs are Under Greater Threat than Thought


In a landmark study, scientists at The Univ. of Queensland (UQ) have simulated future ocean conditions and found climate change will jeopardize the future of coral reefs. The study published in PNAS, finds coral reefs dissolve rapidly once exposed to warmer, more acidic ocean conditions associated with business-as-usual CO2 emission rates predicted for the latter half of this century.

The collaborative study, led by Associate Prof. Sophie Dove from UQ’s School of Biological Sciences, concludes that increases in temperature and acidity cause major disruptions to coral reefs like those growing around the world famous Heron Island on Australia’s Great Barrier Reef.

Dove says even under fairly low emission scenarios, most corals bleached and died.

“Given corals are essential to coral reefs, this is not good news,” Dove says.

In a world-first, the nine-month study used computers to control CO2 content and temperature of water flowing over small patches of coral reef at UQ’s Heron Island research center.

Dove describes one of the most significant challenges of climate change as being able to accurately reduce future uncertainties.

“By simulating future environments above complex reef systems, we come closer to understanding what might happen as the oceans warm and acidify,” she says. “If we can reduce the uncertainty, then we have a much better chance of making better decisions to help protect and conserve these valuable ecosystems.”

The study also found for the first time that increases in ocean temperature and acidity not only leads to a reduction in calcification, the process by which corals build coral reefs, but also the rate at which coral reefs dissolve.

“We discovered that coral reefs under the business-as-usual-emission scenario — the one we are on — show high rates of decalcification,” Dove says. “Essentially, dissolving before our eyes over a few months. This has serious implications for the role of coral reefs in providing habitat for thousands of species and their role in protecting coastlines from wave impacts.”

Studies like these are providing important information and are likely to be considered by the intergovernmental panel on climate change (IPCC).

The first of three major reports by the IPCC will be released next month.

The second report will be released at the end of March in Yokohama, Japan.

Study co-author Prof. Ove Hoegh-Guldberg, from UQ’s Global Change Institute, stressed the importance of scientific research in understanding and solving the problem of rapid anthropogenic climate change.

“One of the key messages of this study is that coral reefs are under even greater threat from ocean warming and acidification than we first thought,” Hoegh-Guldberg says.

“This sounds gloomy but our study also emphasizes the fact that there is time and that small amount of effort today can have a huge impact on what happens in the future.”

The study was funded by UQ’s Australian Research Council’s Centre for Excellence in Reef studies and the Great Barrier Reef Foundation.