Watson Coral Bleaching by Nicola Watson Coral reefs are the most productive and sensitive ecosystems found on Earth. When bleaching occurs, this marine ecosystem is disrupted.
Most corals are examples of endosymbiotic relationships between themselves and photosynthetic algae.
This causes the white calcium carbonate skeleton to be exposed and therefore a whitening of the coral from its original colour. The symbiotic relationship between zooxanthellae and coral is an example of endosymbiosis and is advantageous to both organisms. The coral provides a protected environment for the zooxanthellae to inhabit, and also produces carbon dioxide from respiration, which is used by the algae in photosynthesis. Ammonia, and phosphates are provided by the planktonic animals, on which the coral feeds, and is supplied to the algae as waste products. In return the algae produces oxygen, glucose, glycerol and alanine to the coral by photosynthetic processes.