THE LOCATION: Hawaii
THE STORY: Skeletons on Acid
Corals are stressed out for many reasons. But, as carbon dioxide pollution makes ocean waters more acidic, corals are facing an additional challenge; they are having trouble building up their skeletons. To form their stony metropolis, corals use aragonite, a kind of carbonate that gets depleted faster in acidifying seas. Some climate models predict that as concentrations of atmospheric carbon dioxide exceed 550 parts per million – levels have topped 400 ppm – some reefs around the world could begin to dissolve.
With their existence hinging on whether they can grow faster than they erode, reefs are not only dealing with ocean acidification but other forces as well, such as erosion from waves, nibbling animals and chemicals from land-based pollution. Healthy coral reefs are the foundation of Hawaii's $10 billion-a-year tourism industry. They fill boats with snorkelers and divers, create surf breaks, protect communities from storms and build the state's white sandy beaches.
Many studies have found that corals growing in more acidic seawater have trouble "calcifying," or building limestone skeletons that form reef structures. The same is true for some reef-cementing species such as coralline algae. Since reefs already struggle with other factors, ocean acidification could prove too much to handle. As seas grow more corrosive, coral reefs, which draw more than 7 million visitors to the state each year, could begin to disappear.
Credit: Illustrations of sea life © B. Guild Gillespie / www.chartingnature.com
© Karen Talbot
Hawaii and the value of coral reefs at a glance:
- $364 million estimated value of healthy corals from tourism and education in Hawaii each year
- $3.2 million in gross sales of the aquarium fish industry in 2002
- $40 million estimated added value to coastal properties
- 50% share of federally managed fisheries in the United States that depend on coral reefs for part of their life cycle