Warner,-M.; Fitt,-W.K. Mechanisms of bleaching of zooxanthellate symbioses. AM.-ZOOL. 1991 vol. 31, no. 5, p. 28A. Bleaching of reef corals and other symbiotic invertebrates involves the loss of zooxanthellae and/or reduction in pigment content of these algal cells. This study addresses the cellular mechanisms involved in bleaching, as well as some environmental factors that cause bleaching. The detrimental effects of high temperature on zooxanthellae are exacerbated by exposure to natural light. The role of high temperature and light on pigment concentrations, algal density and algal release rates will be addressed.