Issue Date: April 21, 2008
Ocean Calcification Varies As CO2 Rises
High levels of atmospheric CO2 are making the ocean more acidic, and scientists have predicted that those acidic conditions could reduce all marine organisms' ability to produce calcium carbonate structures. Coral reefs may be degrading, but new research shows that the marine response to ocean acidification will be diverse—including a big boost in calcification for phytoplankton called coccolithophores that should be figured into biogeochemical models (Science 2008, 320, 336). Micrometer-scale coccolithophores (shown) produce roughly one-third of the calcium carbonate in today's oceans. M. Debora Iglesias-Rodriguez of the U.K.'s University of Southampton, Paul R. Halloran of the University of Oxford, and colleagues present lab evidence, confirmed by data collected from sediment cores, that suggests the average coccolithophore's mass has grown by 40% over the past 220 years. The researchers suggest that one reason their lab results differ from previous work with this species is that they adjusted the acidity of seawater in the lab by bubbling in air containing different concentrations of CO2. This method replicates ocean conditions more closely than the hydrochloric acid used in previous studies, they say.
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