Key model outputs for the heat stress temperature, unshaded (a, c, e, g) and shaded (b, d, f, h) treatments: symbiont reserves (carbon, phosphorous and nitrogen (mg m⁻²)) and symbiont biomass (mg N m⁻²) (a, b), normalised internal reserves (nitrogen, phosphorous and carbon (dimensionless)) (c, d), the concentration of chlorophyll a (mg m⁻²) and photosynthetic and photoprotective xanthophyll pigments (mg m⁻²) (e, f), and the normalised fraction of reaction centres in the state oxidised (including oxidised state at 3:00 am (black points)), reduced and inhibited (dimensionless) (g, h). Daily tick marks occur at 0:00 h.