Fig. 4. Changes in Symbiodiniaceae abundance and identity during the 2015–2016 El Niño.

Mean symbiont:host cell ratios (±s.e.) at time points spanning from before to >1 year after the El Niño event for tracked Platygyra ryukyuensis coral colonies that survived (circles) or died (triangles). Sample size refers to the total number of measurements across all time points. Bleaching is indicated by a low cell ratio density (e.g., 0.01). Fitted lines show potential trajectories between sampled time points, and color (blue vs. red) indicates dominant Symbiodiniaceae genus in tracked colonies. The shaded pale yellow area between dashed vertical lines corresponds to >4 degree heating weeks from Fig. 2. Letters indicate significant differences between means for colonies that survived. Symbiont:host ratios were not significantly different across the two 2015 expeditions for colonies that died.