Nature: Promiscuous Partnerships on Coral Reefs May Help Them
Survive Climate Change
Scientists discover shifts to heat-tolerant algae may safeguard devastated reefs from extinction
NEW YORK (Aug. 9) -- Scientists from the Wildlife Conservation Society (WCS), the Center for Environmental Research and Conservation (CERC) at The Earth Institute at Columbia University, and other groups have discovered that coral reefs nearly wiped out by climate change are recovering with unusual heat-resistant algae that may help protect them from future warming.
The large-scale study, to be published in the 12 August 2004 issue of the journal Nature, is the first to document an adaptive response in corals across a wide area that might help them survive the effects of high temperature, which is degrading reef ecosystems worldwide.
Reef-building corals house millions of tiny beneficial algae called ‘symbionts’ that contribute to their dramatic color. When corals are stressed by high temperatures they evict these plant symbionts in a process known as ‘bleaching,’ giving reefs a white appearance. Corals that remain severely bleached for more than a few weeks usually die. During the 1997-98 El Niño warming event, reefs in the Indian Ocean were hit particularly hard, with some regions losing 60% or more of their live coral.
The WCS/CERC-led study compared corals from the Persian Gulf and Red Sea, together with Kenya, Mauritius and Panama, and discovered that unusual algal partners that are thermally tolerant are becoming much more abundant in corals from areas that have been devastated by bleaching. These changes show that ability of corals to flexibly associate with different partners gives them adaptive capabilities that help them cope with rapid environmental change caused by global warming.
“This study shows that corals have a novel response mechanism for dealing with changes in their environment,” said the study’s lead author, WCS/CERC marine conservation zoologist Dr. Andrew Baker. “By being flexible in the kinds of algae they partner with, they are able to respond to change much more rapidly than if they were forced to do this through conventional evolutionary means. Surviving corals from these devastated reefs are likely to be much more resistant to bleaching in the future because they now contain more heat-tolerant algae.”
But Baker emphasizes that these algal shifts only occur once reefs have already experienced severe impacts, and warns that coral reefs are still highly threatened by climate change. “So far we’re only seeing these changes on the world’s most badly hit reefs, and we can continue to expect bleaching and death in many important reef regions. Coral reefs are facing a crisis, and in no way should these results be interpreted as a panacea for the problems facing these ecosystems” says Baker.
Reefs are in trouble globally from not only bleaching, but also from the effects of overfishing, nutrient pollution and habitat destruction. “These findings should motivate our efforts to protect the three-quarters of the world’s coral reefs we still have left, knowing that corals are doing what they can to buy us some time,” says Baker.
The study was funded by the National Science Foundation (NSF), the National Oceanographic and Atmospheric Administration (NOAA) and the Wildlife Conservation Society (WCS).
The Center for Environmental Research and Conservation (CERC), a member of The Earth Institute at Columbia University, is a consortium of five leading New York City science and education institutions - Columbia University, the American Museum of Natural History, The New York Botanical Garden, Wildlife Conservation Society and Wildlife Trust - which trains the next generation of environmental leaders to address the challenges of conserving the Earth's biological diversity.
The Earth Institute at Columbia University is among the world’s leading academic centers for the integrated study of Earth, its environment, and society. The Earth Institute builds upon excellence in the core disciplines—earth sciences, biological sciences, engineering sciences, social sciences and health sciences—and stresses cross-disciplinary approaches to complex problems. Through its research, training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world’s poor. For more information, visit www.earth.columbia.edu.
The Wildlife Conservation Society, a member of CERC, saves wildlife and wild lands through careful science, international conservation, education, and the management of the world’s largest system of urban wildlife parks. These activities change attitudes toward nature and help people imagine wildlife and humans living in sustainable interaction on both a local and a global scale. WCS is committed to this work because we believe it essential to the integrity of life on Earth.