Coral reef communities contain a wide variety of mutualistic associations none more important than the relationship between corals and their symbiotic dinoflagellates of the genus Symbiodinium sp., commonly referred to as zooxanthellae. The function of Zinc (Zn) as cofactor of several enzyme systems such as extracellular carbonic anhydrase (extracellular CA) which catalyzes the interconversion of HCO3- and CO2. Concentrations of dissolved Zn in oligothropic waters are often very low therefore ma