Figure 3: Effect of heat stress on caspase 3 activity and photosynthetic efficiency in Acropora millepora (a) and Pocillopora damicornis. (b). Caspase 3 activity is expressed as percentage of control; PSII efficiency (maximum quantum yield, ) as measured in situ by Pulse Amplitude Modulated (PAM) fluorometry in corals incubated in control (filled circles) and heat stress treatments (open circles). Error bars represent SD; coral branches for caspase 3 activity and coral branches for PAM fluorometry. difference (post hoc LSD analysis, ) between treatment and control for the same time point.