Scientists: Act now to save coral reefs
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07/11/08 Seán Kinane
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Healthy colonies of the corals Porites lobata and Pocillopora damicornis off the coast of Kauai


photo by Seán Kinane

The International Coral Reef Symposium (ICRS) is a gathering of the world’s coral reef scientists and managers that happens only once every four years. This year, the conference was in the United States for the first time since 1977. Three-thousand researchers convened in Ft. Lauderdale on Monday for the meeting that wrapped up today.

ICRS participant Kent Carpenter warned that up to a third of the world’s coral species are in danger of extinction. Carpenter made that claim as lead author in a paper published Thursday in the journal Science.

"We have about 30 percent of species that we were able to assess fall into these extinction risk categories: either vulnerable, endangered or critically endangered. And the potential risk is because of the increased bleaching and disease events that have been occurring with more frequency lately. And this is associated with the rise in sea surface temperatures."

Carpenter described the 39 co-authors of the Science paper as "experts in coral reefs and extinction risks." He said that currently the coral species are just at risk of extinction, but that risk will increase if carbon dioxide emissions continue to rise, causing an increase in sea temperatures. High water temperature is one major cause of bleaching, where corals lose many of the one-celled photosynthetic algae that are normally abundant within coral tissues.

"If the bleaching and disease events occur with even greater frequency, then there’s a very high probability that they will go extinct."

Carpenter is director of the Global Marine Species Assessment Initiative, part of Conservation International and the International Union for the Conservation of Nature. He said the loss of coral species will affect many other types of living things, including humans.

"Coral reefs harbor somewhere around 25 percent of all known marine biodiversity, so if the coral species go extinct, the coral ecosystem will cease to function as an ecosystem. And what will likely occur then is a cascade effect where many other species will go extinct. This is, of course, very dire in terms of the loss of biodiversity. But it’s even more striking to people, because hundreds of millions of people rely on coral reefs for their food and for their livelihood. We’re talking not only about the loss of biodiversity, but also the potential economic impact to hundreds of millions of people."

Rich Aronson is president of the International Society for Reef Studies (ISRS), the group that sanctions the ICRS. (Full disclosure: this reporter is a former ISRS member.) Aronson is a marine scientist at Dauphin Island Sea Lab in Alabama. He said reef growth might not be able to keep up with rising sea levels.

Researchers have been concerned for years that increasing levels of carbon dioxide in the atmosphere will negatively affect coral reefs because of increased sea temperatures. In recent years the acidification of oceans due to increased CO2 has also become a concern and was major issue deliberated at the 2008 ICRS, according to Joanie Kleypas. Kleypas is a marine biologist and geologist with the Institute for the Study of Society and Environment at the National Center for Atmospheric Research in Colorado.

"The bulk of the studies add that the mounting evidence that acidification causes a slowdown in the growth of corals and in coralline algae. Both of these are important to building reef structure. … For first time there’s evidence from the field that calcification rates in corals are declining."

Kleypas said that breakdown in the calcium carbonate structure of coral reefs caused by ocean acidification can only be slowed by a dramatic reduction in carbon dioxide emissions.

Steve Palumbi is a professor of marine ecology and evolution at Stanford University and is cautiously optimistic about the future of the world’s coral reefs. (Full disclosure: As a master’s student at the University of Hawaii, this reporter took classes with Palumbi.)

"Now there’s nothing that we can do to save corals in the long term unless we get rid of our addiction to CO2. We need some sort of 12-step program where we return the world to environmental sobriety and we actually turn this ship around but it’s going to take a century. How do we have corals at the end of that century? Maybe its by individual communities creating their own coral victory gardens in front of themselves that produces the reefs and reef communities that we have in the future."

Nancy Knowlton agrees that humans can opt to protect coral reefs from destruction. Knowlton is the Marine Science chair at the Smithsonian Institution's Museum of Natural History.

"Local protection really matters. Now, it’s definitely the case that if we don’t do something about greenhouse gas emissions, coral reefs are doomed. But in the meantime, protection buys us some incredibly valuable time. "

Photo by Seán Kinane

11th International Coral Reef Symposium

International Society for Reef Studies

One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts

Global Marine Species Assessment Initiative

Conservation International

Steve Palumbi

Joanie Kleypas

Rich Aronson

Dauphin Island Sea Lab

State of Coral Reef Ecosystems of the United States

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