Light spectra and <i>Symbiodinium</i> absorption.

<p>A) Normalised absorption spectrum of <i>Symbiodinium</i>, and defined scalar irradiance spectra used in the experiments in which the OL 490 light engine was used to simulate the <i>in situ</i> light exposure (‘coral tissue’, blue) and ‘halogen lamp’ (red) exposure (in µmol photons m⁻² s⁻¹ nm⁻¹). The scalar irradiance spectra were normalised to give the same integrated output in µmol photons m⁻² s⁻¹ over PAR (400–700 nm). The absorption spectrum of <i>Symbiodinium</i> was normalised to its peak absorption at 465 nm. B) Photosynthetically usable radiation (PUR; see text).