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How does thermal damage trigger coral bleaching?

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

Start year: 2002

Summary: Damage to the photosynthetic mechanism of zooxanthellae has been frequently invoked as the trigger for bleaching of coral. However, we found that zooxanthellae expelled at 33 degrees c were photosynthetically competent and have proposed that the primary event in bleaching is impairment of the mechanism of carbon uptake in the host (Ralph & Larkum, in press). In this proposal we shall test this hypothesis. We will address three questions: i) does time of exposure control the degree of thermal damage in expelled zooxanthellae? ii) can the temperature at which bleaching occurs be manipulated by other factors such as water flow and inorganic carbon supply? & iii) does location of the polyp influence its thermal tolerance?

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