Increasing CO2 in the air also leads to more CO2 in the oceans. In water, the greenhouse gas reacts with water managers attempting to undermolecules to form carbonic acid. Too Nearly one-fifth of the world’s stand the issue on a global scale. much acid wreaks havoc on marine coral reefs have already suclife. The calcium carbonate in coral cumbed to the combined onAn ecosystem fending off many reefs, as well as in the shells of many slaught of global warming, water marine animals, can dissolve in pollution, and overfishing. Withblows acidic waters. In another report on out immediate measures to mitiClimate change is threatening the ocean acidification, released in Nogate climate change and reduce survival of terrestrial and marine vember 2008, scientists at the envithe local pressures on reefs, the ecosystems alike. Like the bacteria ronmental advocacy group world is set to lose anOceana predict widespread other 15% of coral reefs population crashes in marine over the next 10-20 ecosystems, including coral years and 20% over reefs, if we fail to reduce our 20-40 years. Those are carbon emissions over the the main conclusions of next few decades. a new report, produced “Somewhere around jointly by a handful of 480-500 parts per million government agencies and [ppm] CO2 and about two nongovernmental organizations from around the degrees [Celsius] sea temworld, including the U.S. perature rise is about all National Oceanic and Atthat reefs can handle,” Coral reefs like this one in Fiji support a host of marine species. mospheric Administranotes Mark Eakin, coordiThey also provide food and environmental protection to human comtion (NOAA). nator of NOAA’s Coral munities living near the reefs. Reef Watch. The current The report brings some atmospheric concentration “sobering news,” said Clive we harbor in our guts, reef-buildof CO2 is about 380 ppm. Eakin is Wilkinson, the report’s editor, as ing corals host certain microreferring to results from a 2007 he introduced the study at a rescopic algae in their bodies. The paper that he and his colleagues ception held at the National algae provide food to the corals, published in Science. “Now, it Aquarium in Washington, D.C., while the corals give the algae doesn’t mean that they will inon December 9, 2008. “It is clear safe habitat. But, when waters bestantly all keel over at that point,” that human activities continue come warmer, the algae lose he adds. Rather, it implies that if to degrade coral reefs.” some of their green pigments, those thresholds are crossed, the However, not all coral reefs and/or the heat-stressed corals reefs will be unable to deal with are doomed. The 372 coral reef rid themselves of the algae. The additional stressors such as sediscientists and managers from 96 result: corals bleach, starve, and, ment pollution and overfishing, countries who contributed to the in extreme cases, die off. he explains. report also conclude that 46% of Nutrient and sediment polluOne of the best-known coralthe world’s coral reefs are betion, toxic chemicals in water bleaching events attributed to yond the reach of most threats, bodies, overfishing, and illegal warmer sea surface temperatures with the exception of climate fishing are the local and regional happened in 2005, when reefs in change. threats to the survival of coral large swaths of the Eastern CaThis past year, 2008, was the reefs. The multiple blows from ribbean and tropical Atlantic International Year of the Reef. the local and global stressors are bleached. In a paper published The review is the latest in a seweakening these vibrant marine last year in the Proceedings of the ries of scientific papers and ecosystems, reducing their ability National Academy of Sciences agency reports that have docuto survive in their rapidly changU.S.A., marine biologist Simon mented the sad plight of corals ing environment. Donner of the University of Britin the past year. For nearly four ish Columbia (Canada) and his decades, scientists have been colleagues used computer models When coral reefs disappear documenting the health of corto illustrate that the unusually Coral reefs play crucial roles in the als. The recent flurry of studies warm summer of 2005 that vitality and sustainability of coastal is the result of collaborations caused the bleaching was unlikely and ocean ecosystems. They harbor among scientists, environmental to have been from natural clisome of the most diverse plant and advocates, and natural resource matic variations. animal communities in the oceans. ISTOCKPHOTO
Corals in peril
10.1021/es8035048
2009 American Chemical Society
Published on Web 01/07/2009
February 15, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 975
DAVID BURDICK/NOAA
coral reefs. Socioeconomic Concaps, lawmakers and natural reCoralssa group of marine organisms ditions Along the World’s Tropisource managers can help increase that are close relatives of cal Coasts: 2008 includes 14,000 the resilience of reef ecosystems by jellyfishsbuild reefs by secreting mahousehold surveys from 27 comreducing the intensity of local enviterials consisting mainly of calcium munities in tropical countries ronmental stressors. carbonate. The reefs function like and shows that these communi“We have to...look at various ways nurseries for marine life, providing ties depend heavily on coral that we can protect reefs, especially food and habitat to organisms rangreefs for their food and livelimarine protected areas,” says Eakin. ing from algae to squid to countless hood. Coral reefs also provide Numerous places around the world types of fish. protection to these communities have already started to do this, and When coral reefs disappear, the their efforts are beginning to species that live in the reefs pay off, as both of the new go, too. “It’s very straightforreports demonstrate. For ward,” explains Eakin. The example, local communities, survival of species in rain environmental activists, and forests depends on the surpark managers in the Mavival of the forests themhatma Gandhi National Park, selves, he continues. “The in India’s Andaman Islands, more you threaten the rain have successfully reduced forest, the more you’re going coastal littering by enforcing to lose the species. [It’s the] a ban on plastic bottles, same thing with coral reefs.” bags, and other disposable Loss of biological diversity objects. Similarly, two rehas dire consequences for cently designated marine marine ecosystems. “The protected areas in the more genetic diversity we Pacificsthe Papahahave on the reef, the more healthy or resilient that area naumokuakea Marine Nais assumed to be,” says Scott Rising sea surface temperatures make corals evict the algae that tional Monument in the live inside them, causing reefs like this one in Guam to bleach. Donahue of NOAA. Fewer northwest Hawaiian Islands, The bleaching kills some corals; others recover slowly over time. organisms imply less genetic and the Phoenix Islands Prodiversity, which in turn leads tected Areasare cited in the from severe weathersreefs act to reduced ability of a particular spenew report as significant as barriers to storm surges durcies to adapt to environmental achievements. ing hurricanes. “We have to pressures. The fate of corals also depends on make sure we take care of the In a paper published in January the lifestyles people choose for thempeople who live next to coral 2009 in Ecological Applications, selves, notes Donahue. Coral reefs reefs,” says Wilkinson. Marissa Baskett of the University of can be saved if people reduce their California Davis and her colleagues carbon footprint by consuming conat the University of California Santa scientiously. This is not impossible: Can we save the corals? Barbara used computer modeling to people have in the past changed The problem is urgent, says find out how reefs would survive their lifestyles, says Donahue, by givDonahue. “We are in line for different climate and biodiversity ing up chemicals like DDT. “So we changing the global biodiversity scenarios. The results showed that can do it,” he says. “But we need to in a way that may not be able to corals were more likely to survive the do it today.” rebound, particularly in the maonslaught of climate change when rine environment,” he notes. —RHITU CHATTERJEE the reef ecosystems have a variety of Eakin agrees. “We’ve already lost algaesgenetic variants with varying some reefs,” he says, referring to tolerances for higher temperatures. the results of studies that have Saving coral reefs is also crudocumented the declining health cial for the billions of people of coral reefs. “These are reefs whose well-being is linked to that are unlikely to recover in that of the reefs. Coastal econoour lifetime, and [when] we lose mies depend heavily on coral species they’re gone forever.” reefs. More than 2 billion people Protecting reefs will require drastic living in coastal areas depend on reductions in emissions of greenreefs for survival, according to a house gases. But, while nations second report released along bicker over emission targets and with the report on the status of struggle with implementing those 976 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / February 15, 2009
