Light-enhanced calcification and dark decalcification in isolates of the soft coral Cladiella sp. during tissue recovery.

Light-enhanced calcification is a general characteristic of zooxanthellate corals, suggesting a link between calcification by the coral and photosynthesis by the zooxanthellae, but the relationship between zooxanthellae and coral hosts during this process has not been elucidated. We hypothesized that the effects of tissue injury on the coral fragments used in experiments studying calcification might obscure that link. To detect the effects of tissue injury on light-enhanced calcification, we measured calcification rates (sclerite formation) in the soft coral Cladiella sp. by the alkalinity anomaly method during a 36-day experiment following injury associated with coral fragmentation. In the 2 weeks after colony fragmentation, the calcification response did not show a relation with light intensity. The typical light-enhanced calcification pattern was not noticed until day 15 of tissue recovery. The calcification rate of this soft coral increased with light intensity and time of tissue recovery and was comparable to that of hard corals exposed to similar experimental conditions. However, Cladiella sp. decalcified in the dark. The diurnal calcification-decalcification cycles probably control sclerite size and shape.