Changes in quantum efficiency of Photosystem II of symbiotic dinoflagellates of corals after heat stress, and of bleached corals sampled after the 1998 Great Barrier Reef mass bleaching event

• DOI: 10.1071/mf99100
• Publication Date: 2005-11-18T07:11:47Z
• Authors: Ross J. Jones; Selina Ward; Affendi Yang Amri; Ove Hoegh-Guldberg
• Keywords: Dinoflagellate; Coral bleaching; Zooxanthellae; Hermatypic coral

Pulse–amplitude–modulation chlorophyll fluorometry was used to examine changes in dark-adapted Fv/Fm of endosymbiotic dinoflagellate microalgae within the tissues temperate coral Plesiastrea versipora exposed elevated seawater temperature. The markedly reduced following exposure corals 28°C for 48 h. When were returned ambient (24°C) conditions, increased an initial rapid and then secondary slower phase. Tissue discolouration (coral bleaching), caused by a significant decrease density algae, observed during first 2–3 days recovery period. After 14 days, still significantly lower than control corals. is discussed terms repair processes symbiotic division healthy algae also selective removal photo-damaged dinoflagellates. Under field bleached sampled at Heron Island Reef bleaching event had non-bleached colonies; four months after event, there no differences F v /F m or algal marked as having shown signs colour loss. results this laboratory study are consistent with hypothesis that impairment photosynthesis occurs heat-stress, underlying cause bleaching.