Cause and Ecological Consequence. Coral bleaching is a vivid sign of corals responding to prolonged physiological stress induced by increased or reduced water temperatures (often attributed to global warming). If these symbiotic zooxanthellae algal cells are expelled, the host may die shortly afterwards.
The potential loss of these coral ecosystems will have devastating effects for reef-depenent species as well as the considerably large human population that depends on coral reef resources for economic and food security.
A) Healthy zooxanthellae living in coral tissue.
B) Bleached coral zooxanthellae expelled from coral tissue.