Abstract
Coral reef “bleaching”, has long been considered a pathological response to a variety of environmental stresses. Given the threat of climate change, and the documented mass mortalities of corals as a result of episodic bleaching caused by high temperatures, environmental triggers have become the focus for the vast majority of contemporary bleaching studies. This chapter outlines and reviews the various factors, other than high temperature, high light and infectious agents, which have been reported to cause coral bleaching. It compares and contrasts these factors in terms of the critical thresholds which trigger bleaching, the mechanisms underlying the bleaching response, and the associated disease signs (in addition to loss of symbionts and/or photosynthetic pigments) which can accompany bleaching in each case. The chapter also highlights responses which might reflect an “animal stress response” rather than an “algal stress response” and identifies common targets of stress in each partner, wherever possible.