Effect of calcium carbonate saturation of seawater on coral calcification

摘要: Abstract The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface supersaturated with respect aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography recent corals. We investigated calcification rates five colonies zooxanthellate coral Stylophora pistillata synthetic using alkalinity anomaly technique. Changes aragonite saturation from 98% 585% were obtained manipulating calcium concentration. results show nonlinear increase rate as function level. Calcification increases nearly 3-fold when 390%, i.e., close typical present state tropical seawater. There no further at values above this threshold. Preliminary data another species, Acropora sp., displays similar behaviour. These experimental suggest: (1) does change significantly within range levels corresponding last glacial-interglacial cycle, (2) may decrease future result level due anthropogenic release CO2 into atmosphere. Experimental studies control environmental conditions composition provide unique opportunities unravel response global changes.