Effects of increased pCO2 on zinc uptake and calcification in the tropical coral Stylophora pistillata

Zinc (Zn) is an essential element for corals. We investigated the effects of ocean acidification on zinc incorporation, photosynthesis, and gross calcification in the scleractinian coral Stylophora pistillata. Colonies were maintained at normal pH(T) (8.1) and at two low-pH conditions (7.8 and 7.5) for 5 weeks. Corals were exposed to Zn-65 dissolved in seawater to assess uptake rates. After 5 weeks, corals raised at pHT (8.1) exhibited higher Zn-65 activity in the coral tissue and skeleton, compared with corals raised at a lower pH. Photosynthesis, photosynthetic efficiency, and gross calcification, measured by Ca-45 incorporation, were however unchanged even at the lowest pH.