A diverse
range of stress factors (e.g. low salinity, low temperature, high sedimentation,
aerial exposure, cyanide exposure) can initiate the
bleaching response, although the combination of high irradiance
and anomalously warm sea surface temperatures (SSTs) is the primary
triggering condition for the modern occurrence of large-scale
mass bleaching events (reviewed by Hoegh-Guldberg, 1999). Indeed,
coral bleaching has consistently occurred where normal
summer sea temperatures have exceeded ambient by 1–2 C for
more than a few days (Hoegh-Guldberg, 1999).