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Thermal bleaching response of coral zooxanthellae

Project Member(s): Ralph, P., Larkum, A.

Start year: 2001

Summary: While a number of factors such as high light, high temperature, low salinity and UV exposure have been linked to coral bleaching, the best explanation for rcent coral bleaching events is small temperature excursions of 1 to 2% above summer sea temperatures which induce the dinoflagellate symbionts (zooxanthellae) to be expelled from the host. The mechanism which triggers this expusion of the algal symbionts is not known, but has been attributed to damage to the photosynthetic mechanism of the zooxanthellae. We will address three basic questions: i) what triggers the expulsion of zooxanthellae?; ii) are expelled zooxanthellae photosynthetically competent after expulsion?; and iii) does the host affect the symbionts' ability to survive?

Keywords: coral; photobiology; physiology; bleaching

FOR Codes: Plant Physiology, Invertebrate Biology, Climate change, Physical and chemical conditions, Physical and Chemical Conditions of Water in Marine Environments