To assess possible pa-GFP protein level shifts in treated corals, we re-analyzed a subset of microscopy images from the venetoclax experiment to gain the information of “green to area” and “red to area” signal, representing the raw GFP and chlorophyll-derived signals normalized to the analyzed area (Fig. S6). The results show that in ven- heat-stressed corals, it is the symbiont-derived signal that decreases more in NPC corals than in PC corals, while in ven+ heat-stressed corals, it decreases in both NPC and PC corals similarly. Host-derived signal in these corals does not change dramatically, except for ven- PC coral #10, where it increases. However, the symbiont-derived signal in the ven- heat-stressed corals decreases more in NPC coral than in PC coral, so the increase in host-derived signal does not explain the differences in the bleaching rate between NPC and PC corals alone. Finally, the visual assessment of coral bleaching (Fig. S4) supports the differences in symbiont:host signal ratio in treated corals are based on the differences in bleaching rate, i.e. in the loss of symbionts.