Meeting Abstract

4-1  Friday, Jan. 4 08:00 – 08:15  Ocean acidification and warming impact physiology of the algal symbiont to a greater extent than the host in four common Caribbean corals BOVE, CB*; DAVIES, SW; RIES, JB; UMBANHOWAR, J; CASTILLO, KD; University of North Carolina at Chapel Hill ; Boston University; Northeastern University; University of North Carolina at Chapel Hill ; University of North Carolina at Chapel Hill colleenbove@gmail.com

Increasing carbon dioxide from anthropogenic sources is of growing concern as global average atmospheric pCO₂ has now increased from a pre-industrial level of 280 μatm to 410 μatm, causing ocean temperatures to rise and pH to decline. Corals are particularly vulnerable to these stressors, most likely due to their reliance on their algal symbionts (Symbiodiniaceae) and their use of carbonate ions in calcification. We conducted a 93-day experiment investigating independent and combined effects of acidification (280−3300 μatm pCO₂) and warming (28, 31 °C) on the physiological responses of the coral host (total protein and carbohydrate) and algal symbiont (symbiont density, chlorophyll content, colour analysis) of four Caribbean coral species (Siderastrea siderea, Pseudodiploria strigosa, Porites astreoides, Undaria tenuifolia ) from inshore and offshore reefs on the Belize Mesoamerican Barrier Reef System. Results show that coral hosts are generally able to maintain energy reserves under acidification and warming, while symbiont densities decline and become less productive as pCO₂ and temperature increase. These results contrast previous assumptions that coral hosts are more susceptible to ocean acidification and warming than their algal symbionts, and provide valuable insight into the future projections for these Caribbean corals under global change.