Figure 1
From: Deoxygenation lowers the thermal threshold of coral bleaching
Deoxygenation lowers the thermal threshold of coral bleaching. (a) Short-term thermal stress assay profiles with respective 3 h heat-hold temperatures at 30 °C (control/baseline), 33 °C, 36 °C, and 39 °C under normoxic (H0) and deoxygenation (Hd) conditions. For Hd, the deoxygenation condition was applied for a total of 6 h (during daylight hours). Samples for RNA-Seq analysis were taken after 6 h, i.e. at the end of the heat-hold as indicated by T1. Measurements of maximum photosynthetic efficiency of PSII (Fv/Fm) of the additional fragments were taken following 1 h dark-acclimation. (b) Representative photographs of coral fragments from time point T0 and T1 under H0 and Hd. (c) Maximum photosynthetic efficiency of PSII (Fv/Fm) in relation to temperature for H0 vs. Hd (n = 3 for each) and determined ED50 thermal tolerance thresholds as a proxy for coral bleaching susceptibility (sensu29,49). Solid lines reflect the log-logistic model with 95% confidence intervals represented by the shaded areas. (d) Principal Component Analysis (PCA) of 20,115 transcripts comparing all H0 and Hd samples across all heat stress temperatures (n = 4 for each). The x- and y-axes indicate the percent of the variance explained by the first and second principal component, respectively.
