EFFECTS OF OCEAN WARMING AND CO2-INDUCED ACIDIFICATION ON CALCIFICATION OF FOUR CARIBBEAN REEF-BUILDING CORALS
Rising atmospheric carbon dioxide (pCO2) has caused ocean temperature to increase and pH to decrease, raising concerns about the health of marine organisms. Corals are particularly vulnerable to these stressors, likely due to their narrow thermal tolerance and use of carbonate ions in calcification, although response patterns vary across taxa. We conducted controlled laboratory experiments for approximately 90 days to investigate the independent and interactive effects of ocean warming (28, 31 C) and acidification on the calcification rate and skeletal properties of four keystone Caribbean reef-building corals (Pseudodiploria strigosa, Siderastrea siderea, Porites astreoides, Undaria tenuifolia) collected from the Belize Mesoamerican Barrier Reef. Aragonite saturation states of 3.9, 3.2, 2.2, and 0.7 constrained by total alkalinity measured via closed-cell potentiometric titration and dissolved inorganic carbon measured via coulometry, were attained by sparging natural seawater with air-CO2 mixtures formulated at 280, 400, 700, and 2800 ppm pCO2, respectively. Temperature and pCO2 were fully crossed with three-fold treatment replication. Calcification rates for all species exhibited a generally decreasing trend with increasing pCO2, although this trend was not always linear. The negative effects of pCO2 were more pronounced at 28C than at 31C. Notably, three of the species exhibited net skeletal dissolution in the treatments that was undersaturated with respect to aragonite, with only S. siderea producing skeleton on a net basis under these conditions.
Bove, C. B., University of North Carolina at Chapel Hill, USA, firstname.lastname@example.org
Ries, J. B., Northeastern University, USA
Davies, S. W., University of North Carolina at Chapel Hill, USA
Westfield, I. T., Northeastern University, USA
Castillo, K. D., University of North Carolina at Chapel Hill, USA
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