Bcl-2 is involved in both apoptosis and autophagy pathways (Xu et al., 2013). In order to distinguish between these two programmed cell death pathways, we analyzed activity of caspase-3, one of the key apoptotic effector proteases, and acid phosphatases (APs) which play an important role in autophagosome-lysosome fusion. Increased activity of both types of these enzymes have been previously observed during the loss of symbionts in corals (Downs et al., 2009; Fitt & Trench, 1983; Hohman, McNeil, & Muscatine, 1982; O’Brien, 1982; Pernice et al., 2011; Tchernov et al., 2011). We performed the enzymatic activity assays in thermally stressed PC and NPC corals at 12, 24, and 72 hours of heat stress, and in PC and NPC corals treated with venetoclax to exclude the switch in PCD pathways upon treatment. As controls, we treated corals with apoptosis inducer colchicine (Tchernov et al., 2011) and autophagy inducer rapamycin (Dunn et al., 2007).