Scleractinian corals with photoprotective host pigments are hypersensitive to thermal bleaching

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 272:99-116 (2004) - doi:10.3354/meps272099 Scleractinian corals with photoprotective host pigments are hypersensitive to thermal bleaching Sophie Dove* Centre for Marine Studies, University of Queensland, St Lucia, Queensland, 4072, Australia *Email: sophie@uq.edu.au ABSTRACT: Recent episodes of mass coral bleaching, the loss of symbiotic dinoflagellates or photosynthetic pigment from hermatypic corals, have been triggered by elevated sea temperatures. Photosynthetic irradiance is an important secondary factor. Host based pigments (pocilloporins or Green Fluorescent Protein homologues) have been proposed to reduce the impact of elevated temperature by shading the dinoflagellate symbionts of corals, thereby reducing light stress. This study investigates this phenomenon in the reef-building coral Acropora aspera from Heron Island Research Station (Great Barrier Reef, Australia), which occurs as 3 distinct colour morphs. Experimental data showed that the host pigments are photoprotective at normal temperatures or <32°C; however, the loss of symbionts and reduction in the quantum yield of photosynthesis (dark adapted Fv/Fm) observed after exposure to elevated temperature was most severe in the heavily pigmented blue morph, eventually resulting in death of most experimental colonies. The results suggest that the protection offered by pocilloporins and other GFP-homologues is reduced by thermal stress, potentially leaving the shade-acclimated symbionts of heavily pigmented corals exposed to high light levels. Mature host pigments are thermally stable, but they are potentially vulnerable to heat during mRNA and protein synthesis and/or maturation. It is clear, however, that the broad assumption that host pigmented corals are less vulnerable to thermal stress is incorrect. KEY WORDS: Host pigments · GFP · Photoinhibition · Bleaching · Scleractinian corals Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 272. Online publication date: May 19, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.