Effects of Nutrient Enrichment and Elevated CO2 Partial Pressure on Growth Rate of Atlantic Scleractinian Coral Acropora cervicornis

The growth rate of Acropora cervicornis branch tips maintained in the laboratory was measured before, during, and after exposure to elevated nitrate (5 and 10 μM NO ₃ ^- ), phosphate (2 and 4 μM P-PO ₄ ³ ) and/or pCO ₂ (CO ₂ ~700 to 800 μatm). The effect of increased pCO ₂ was greater than that of nutrient enrichment alone. High concentrations of nitrate or phosphate resulted in significant decreases in growth rate, in both the presence and absence of increased pCO ₂ . The effect of nitrate and phosphate enrichment combined was additive or antagonistic relative to nutrient concentration and pCO ₂ level. Growth rate recovery was greater after exposure to increased nutrient or CO ₂ compared to increased nutrients and CO ₂ . If these results accurately predict coral response in the natural environment, it is reasonable to speculate that the survival and reef-building potential of this species will be significantly negatively impacted by continued coastal nitrification and projected pCO ₂ increases.