ALT Survey design of the study, showing (a) the location of the 20 sampling sites in eastern Australia; image examples of the outlined coral communities from (b) Lady Elliot Island and (c) Black Rock. The 0.5 m black and yellow graduated calibration stick is visible. Corals that were not completely in frame, like the largest one in (c) were not included in the final dataset.

ALT (a) The number of coral colonies decreases with PC1 and (b) increases with PC2. (c) Median coral colony size increases with PC1. (d) Skewness of the coral size–frequency distribution decreases with increasing PC1 and (e) increases with PC2. The black line is the line of best fit, and the grey region is the 95% confidence band. The explanatory variables plotted here were chosen based on model selection (Supporting information). For (a, c and d), more positive PC1 scores represent lower sea surface temperature and photosynthetically available radiation (PAR), i.e. colder and darker, and high chlorophyll a concentration and turbidity (kd490), i.e. more productive and more turbid. In (b) and (e) more positive PC2 scores represent higher minima of chlorophyll a concentration and kd490 i.e. lowest turbidity and productivity is least extreme; and lower standard deviations of PAR i.e. more stable light regimes.