Slowing skeletal growth
Experimental studies, such as those conducted by one of the report's authors, Chris Langdon at the University of Miami, show that coral calcification consistently decreases as the oceans become more acidic. This means that these organisms will grow more slowly, or their skeletons will become less dense, a process similar to osteoporosis in humans. As a result, reef structures are threatened because corals may be unable to build reefs as fast as erosion wears away the reefs.
"This threat is hitting coral reefs at the same time that they are being hit by warming-induced mass bleaching events," Langdon says. Mass bleaching occurs when unusually warm temperatures cause the coral to expel the colorful microscopic algae that provide the coral polyps with food.
Many calcifying organisms--including marine plankton such as pteropods, a planktonic marine snail--are affected by the chemistry changes. Shelled pteropods are an important food source for salmon, mackerel, herring, and cod. If calcifying organisms such as pteropods are unable to sustain their populations, many other species may be affected.
"Decreased calcification in marine algae and animals is likely to impact marine food webs and has the potential to substantially alter the biodiversity and productivity of the ocean," says Victoria Fabry of California State University, San Marcos, who is another of the report's authors.
Threats to major ecosystems
Several other major ecosystems that are supported by marine calcifiers may be particularly threatened by ocean acidification. These include cold-water reefs, which are extensive structures that provide habitat for many important fish species, particularly in the coastal waters of Alaska.
The report outlines future research to understand this consequence of climate change. While scientists cannot yet fully predict how much ma
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Contact: David Hosansky
hosansky@ucar.edu
303-497-8611
National Center for Atmospheric Research/University Corporation for Atmospheric Research
5-Jul-2006