Coral adaptation and acclimatization: A most ingenious paradox

Reef corals and the communities they form evidently possess effective mecha nisms of adaptation and acclimation that have ensured their survival and re currence over geologic time, Current reef degradation suggests that these m echanisms are being taxed beyond their limits; understanding of the problem is hampered by serious inadequacies in our understanding of physiological stress responses, the range and implications of reproductive strategies, an d the mechanisms of calcification and algal symbiosis, Reef community and p opulation responses to environmental change appear substantially different on different time scales, and a combination of short-term perspectives and definitional confusion complicates interpretation and prediction of reef re sponses. Calcium carbonate saturation state is now recognized as a potentia lly important control of reef calcification, which means that rising atmosp heric CO2 represents a direct threat to reef ecosystems on a global scale.