Effect of calcium carbonate saturation of seawater on coral calcification

Global and Planetary Change
By: , and 



The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (l) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effect of calcium carbonate saturation of seawater on coral calcification
Series title Global and Planetary Change
DOI 10.1016/S0921-8181(98)00035-6
Volume 18
Issue 1-2
Year Published 1998
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Global and Planetary Change
First page 37
Last page 46
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