Branches and plates of the morphologically plastic coral Porites rus are insensitive to ocean acidification and warming

This study tested the hypothesis that intraspecific morphological plasticity within a scleractinian coral elicits differential responses to elevated P-CO2 and temperature. In Mo'orea, French Polynesia, two short-term laboratory experiments (21 and 14 days) were conducted to test the effects of P-CO2 (400 vs. 700 mu atm), and P-CO2 (400 vs 1000 mu atm) combined with temperature (27.0 vs. 29.8 degrees C), on branches and plates of Porites rus. Experiments employed two irradiances (similar to 1000 vs 200 mu mol photons m(-2) s(-1)), which characterized the microenvironments on the shallow fringing reefs where branching and plating morphologies are common, respectively. Calcification of both morphologies was insensitive to Pan, as well as the combined effects of elevated P-CO2 and temperature. Mean calcification rates were faster in high light than in low light for both morphologies, and biomass was greater in plates than branches in all treatments. Together, our results suggest P. rus is robust to increased Pan and high temperature within the constraints of the treatments applied. Morphological plasticity in this species does not mediate physiological resistance to low pH and high temperature. (C) 2016 Elsevier B.V. All rights reserved.