MEPS 136:235-244 (1996)  -  doi:10.3354/meps136235

The bleaching response in intertidal Goniastrea aspera (Verrill) was investigated immediately at the onset of a natural bleaching event caused primarily by elevated solar irradiance. Bleaching was found to involve a significant decrease in zooxanthellae density and a significant reduction in chlorophyll c content of zooxanthellae. In contrast chlorophyll a content of zooxanthellae appeared to increase in bleached compared to normally pigmented tissues, an effect which may have been the result of interference of chlorophyll breakdown products with the pigment analysis. Bleaching damage was restricted at the cellular level to those host endodermal cells harbouring zooxanthellae, both of which exhibited cellular degradation. In bleached tissues, in situ degradation of zooxanthellae, prior to their loss from host tissues, appeared to be the principal factor associated with reduction in algal density. The results highlight that the mechanism of bleaching is a complex response involving changes in the symbiotic association between specific host and zooxanthella cells, zooxanthella densities and pigment content.

Coral . Zooxanthellae . Symbiosis . Bleaching